JP2002182051A - Optical waveguide module - Google Patents

Abstract

(57) [Problem] To provide an optical waveguide module in which the configuration of an optical circuit is simplified and light intensity can be monitored correctly regardless of the polarization state of signal light. SOLUTION: In an optical planar waveguide type circuit 1, an oblique groove 3 is formed at an inclination angle θ with respect to a vertical axis so as to cross an optical waveguide _2n . Then, inside the groove 3, a reflection filter 4 configured to compensate for the difference in the reflectance between the orthogonal polarizations with respect to the signal light is installed, and the light reflected from the reflection filter 4 is detected by the photodetector 6 _n . Detect and monitor the light intensity of the signal light. This makes it possible to monitor the light intensity correctly regardless of the polarization state of the signal light. Further, since the inside of the groove 3 including the reflection filter 4 is sealed with the filling resin 5, deterioration of long-term operation stability due to contamination of the groove 3 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical waveguide module having a planar waveguide type optical waveguide formed on a substrate.

[0002]

2. Description of the Related Art In an optical circuit using an optical waveguide such as an optical fiber or an optical planar waveguide, the optical intensity of the signal light is preferably adjusted such that the optical intensity of the signal light transmitted through each optical waveguide is kept constant. It may be desirable to control to a value. In such a case, the light intensity of the signal light is monitored in an optical circuit, or the light intensity is controlled based on the monitored result.

[0003]

In order to monitor the light intensity of the signal light, a method of providing an optical coupler on an optical waveguide and branching a part of the signal light is conventionally used. In this method, an optical coupler is provided at a predetermined position on an optical waveguide to split signal light by about several percent, and the light intensity of the split light is monitored by a photodetector, whereby the optical waveguide is transmitted. The light intensity of the signal light is monitored.

However, when the optical coupler is used as described above, the number of optical components constituting the optical circuit increases, and it is necessary to fusion-splice them, which complicates the configuration and manufacturing process of the optical circuit. There is a problem of doing.

On the other hand, there has been proposed a method of monitoring the light intensity by partially reflecting signal light without using an optical coupler. For example, in an optical device described in Japanese Patent Application Laid-Open No. 6-331837, an end surface that is oblique to an optical axis is formed at a predetermined portion of an optical waveguide, and signal light reflected from the end surface in a direction different from the optical axis. The reflected light which is a part of is detected, and the light intensity is monitored. Also, Japanese Patent Application Laid-Open
The optical fiber described in JP-155235A relates to a light branching / merging structure, and forms an end face perpendicular to an optical axis at a predetermined portion of the optical fiber to emit a part of signal light to the outside. Then, a part of the emitted light is reflected by another end face oblique to the optical axis and extracted.

However, when a part of the signal light is reflected and used for monitoring the light intensity, the reflectivity of the signal light at the oblique end face differs depending on the polarization state of the reflected signal light. Has become. For this reason, there is a problem that unless the polarization state of the signal light transmitted through the optical waveguide is specified, the light intensity cannot be monitored correctly. Further, when the end face of the optical waveguide is exposed to the outside air, contamination of the end face deteriorates long-term stability such as reflectance.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to simplify the configuration of an optical circuit and to monitor the light intensity correctly regardless of the polarization state of signal light. It is an object to provide a possible optical waveguide module.

[0008]

In order to achieve such an object, an optical waveguide module according to the present invention comprises:
A substrate, and a planar waveguide type optical waveguide formed on the substrate, and a predetermined inclination angle θ with respect to a vertical axis orthogonal to the optical axis of the optical waveguide so as to cross a predetermined portion of the optical waveguide. (2) an optical plane waveguide type circuit having a groove formed obliquely at (0 ° <θ), and (2) a portion through which the signal light transmitted through the optical waveguide passes inside the groove of the optical plane waveguide type circuit. And a reflection filter that reflects a part of the signal light with a predetermined reflectance in which the reflectance difference between the orthogonal polarizations is compensated, and (3) sealing at least the inside of the groove. And (4) a photodetector that detects the reflected light of the signal light reflected by the reflection filter.

In the above-described optical waveguide module, the optical waveguide is not branched by the optical coupler, but a part of the signal light is reflected by the diagonal groove provided on the optical waveguide, and the reflected light reflects the light of the signal light. The configuration is such that the intensity can be monitored. This simplifies the configuration and manufacturing process of the optical circuit.

In addition, instead of reflecting the signal light by the end face of the groove, a reflection filter that realizes polarization compensation for equalizing the reflectance between the respective polarization states is installed inside the groove.
A part of the signal light is reflected by the reflection filter and used for monitoring the light intensity. At this time, the reflectivity of the signal light by the reflection filter is substantially constant irrespective of the polarization state of the signal light transmitted through the optical waveguide, so that the light intensity is correctly monitored regardless of the polarization state of the signal light. It becomes possible. Further, since the inside of the groove including the reflection filter is sealed with the filling resin, the end face of the groove and the reflection filter do not come into contact with the outside air, and deterioration of long-term stability due to contamination of the end face and the like is prevented. .

Here, the inclination angle θ of the groove formed in the optical planar waveguide type circuit is preferably in an angle range of 0 ° <θ ≦ 40 °.

When the inclination angle θ of the groove and the reflection filter with respect to the vertical axis increases, the signal light is reflected at a large angle. At this time, the difference in the reflectance between the orthogonal polarizations increases, and the reflection filter It is difficult to compensate for the difference in reflectance due to On the other hand, if the inclination angle θ is within the above-described angle range, it is possible to sufficiently compensate for the difference in the reflectance in the reflection filter.

Further, the present invention is characterized in that a resin material having substantially the same refractive index as the core of the optical waveguide is used as the filling resin. As a result, unnecessary reflection of signal light at the end face of the groove that is the interface between the optical waveguide and the filling resin is suppressed.

Further, the filling resin is added to the inside of the groove,
An internal filling resin that fills a predetermined area of the upper surface of the optical planar waveguide circuit including the upper side of the groove and seals the inside of the groove, and seals an upper surface of the optical planar waveguide circuit. It is preferable to use resin materials having substantially the same refractive index as each other for the upper filling resin.

This makes it possible to control not only the extra reflection of the signal light (reflected light) at the interface of the inner filling resin but also the extra reflection of the signal light (reflected light) at the interface of the upper filling resin. Become. Here, if the same resin material is used for the inner filling resin and the upper filling resin, the step of filling the resin can be simplified.

A coating film (anti-reflection coating) for preventing reflection of a light wavelength band to be used is provided at an interface between the optical planar waveguide circuit and the photodetector or an interface between the filling resin and the photodetector. It is characterized by having been done. The refractive index of a photodetector usually differs greatly from the refractive index of an optical waveguide or a filling resin. On the other hand, if an antireflection coat is provided as necessary, extra reflection that occurs when reflected light is incident on the photodetector is suppressed, and the polarization dependence caused by the reflection is suppressed. Can be.

Further, the light receiving surface of the photodetector is characterized in that it is formed in a substantially elliptical shape including an elliptical reflected light spot due to the reflected light reflected by the reflection filter.

Since the signal light transmitted through the optical waveguide has a circular signal light spot from the core shape, the spot of the reflected light reflected by the oblique reflection filter has an elliptical shape. On the other hand, if the light receiving surface of the photodetector is formed to have a substantially elliptical shape, it is possible to reduce the occurrence of noise and the like from unnecessary light receiving surface portions, and to improve the efficiency of light intensity monitoring. Further, since the width of the light receiving surface in the arrangement direction perpendicular to the optical axis of the optical waveguide can be minimized, when the photodetector array is installed corresponding to the optical waveguide array, the arrangement pitch of the photodetectors is reduced. Can be reduced and an efficient optical circuit configuration can be realized.

Further, the optical waveguide module has N (N is a plurality) optical waveguides as optical waveguides of the optical planar waveguide type circuit, and N optical waveguides corresponding to the N optical waveguides are used as photodetectors. Of the signal light transmitted through each of the N optical waveguides, and N light paths reflected by the reflection filter to the corresponding light detectors. A light path separating means for separating the reflected light paths from each other is provided between each of the reflected light paths.

As described above, when the optical planar waveguide type circuit has N (N-channel) optical waveguides and monitors the light intensity of the N-channel signal light transmitted through each optical waveguide, The N-channel signal light reflected by the reflection filter propagates through a predetermined reflection light path, and is detected by a corresponding photodetector. At this time, while the signal light from the optical waveguide reflected by the reflection filter is detected by the corresponding photodetector, the light scattering, reflection, spread of the transmitted light, etc. caused by the filter and other places cause the signal light. In some cases, a part of the light may be incident on a photodetector of another adjacent channel and detected, and crosstalk may be deteriorated.

On the other hand, by providing the optical path isolation means between the adjacent reflected light paths as described above, it is possible to minimize the occurrence of crosstalk between adjacent channels. This makes it possible to accurately monitor the light intensity of the signal light in each channel of the N-channel signal light transmitted through each optical waveguide.

Further, as a configuration for isolating the reflected light paths, the light path isolating means is provided in the optical planar waveguide type circuit so as to block the light passing from the reflected light path to the adjacent reflected light path. A configuration that is a light shielding means provided between each of the optical waveguides of the book is preferable. Alternatively, it is preferable that the optical path isolating means is a light shielding means provided to shield light passing from the reflected light path to the adjacent reflected light path in the filling resin.

As described above, by providing the light shielding means in the optical planar waveguide type circuit or the filling resin, it is possible to reliably prevent the occurrence of crosstalk between adjacent channels. As such a light shielding means, it is preferable to use a light shielding material having an effect of shielding light by absorbing, reflecting or scattering light having a signal light wavelength.

As a specific configuration in the case where the light shielding means is provided in the filling resin, the filling resin is added to the inside of the groove,
For filling a predetermined range on the upper surface of the optical planar waveguide type circuit including the upper side of the groove, and for mounting N photodetectors on the upper surface side of the optical planar waveguide type circuit. A mounting member (mount member) is provided, and the light shielding means includes a light shielding portion provided on the mounting member so as to protrude into an upper filling resin for sealing an upper surface of the optical planar waveguide type circuit. Can be used. Further, a configuration in which light shielding means is provided separately from the mounting member may be used.

Of course, simply providing a groove as an optical path isolating means between the waveguide cores of the optical waveguide can provide an appropriate groove width,
By providing the groove side walls with roughness or the like, the effect of suppressing scattered light and preventing the occurrence of crosstalk can be obtained.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an optical waveguide module according to the present invention will be described below in detail with reference to the drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description. Also, the dimensional ratios in the drawings do not always match those described.

FIG. 1 is a plan view showing the configuration of the first embodiment of the optical waveguide module according to the present invention. This optical waveguide module comprises a substrate 10 and eight (8-channel) optical waveguides 2 _{1 of} a planar waveguide type formed on the substrate 10.
2 to ₈ are provided.

[0028] Each of the optical waveguide 2 ₁ to 2 _8, along a predetermined optical transmission direction (a direction indicated by an arrow in FIG. 1), and from the input end 11 of the optical planar waveguide circuit 1 towards the output end 12 Are formed parallel to each other and at equal intervals. Further, the predetermined site for the optical transmission direction of the optical planar waveguide circuit 1, are provided grooves 3 crossing the optical waveguide 2 ₁ to 2 _8.

[0029] The groove 3, the optical waveguides 2 ₁ - on the inside thereof
With 2 ₈ reflection filter 4 for reflecting a portion of the transmitted signal light is installed, it is sealed by filling resin 5. Above the optical planar waveguide circuit 1 at a position upstream of the groove 3, along with the sub-mount substrate 7 they are placed, above the filling resin 5 and the sub-mount substrate 7, the optical waveguide 2 ₁ photodetector array 6 with ~ 2 ₈ eight photodetectors ₆₁ through ₈ corresponding respectively is installed. An optical planar waveguide type circuit 1 and a submount substrate 7,
The submount substrate 7 and the photodetector array 6 are fixed by, for example, solder.

[0030] In FIG. 1, the photodetector ₆₁ through ₈
The shape of each light receiving surface is illustrated by a dotted line. The submount substrate 7 is a mounting member (mounting member) on which the photodetector array 6 is mounted, and has a photodetector on its upper surface, as schematically shown in FIG. vessel 6 wirings, electrodes, etc. for reading the light detection signal from _one to six ₈ is formed.

FIG. 2 shows the cross-sectional structure of the optical waveguide module shown in FIG. 1 along the optical axis direction of the optical waveguide 2 _n (n = 1 to 8) (the optical transmission direction of the optical planar waveguide circuit 1). FIG. In FIG. 2, a portion including the groove 3, the reflection filter 4, and the photodetector array 6 is shown in an enlarged manner.

Optical waveguide 2 in optical planar waveguide type circuit 1
_n is the lower cladding 22, the core 2 as shown in FIG.
0 and the upper cladding 21 are formed on the substrate 10. On the other hand, the optical waveguide 2
_The groove 3 traversing the _n at a predetermined portion corresponds to the core 20 and has a depth d including at least a portion through which the signal light transmitted through the optical waveguide 2 _n passes, and is orthogonal to the optical axis of the optical waveguide 2 _n (the substrate 10).
It is formed obliquely at a predetermined inclination angle θ (0 ° <θ) with respect to a vertical axis (indicated by a dotted line in FIG. 2) perpendicular to the vertical axis. In the present embodiment, the depth d of the groove 3 is set to be larger than the thickness of the optical waveguide _2n .

A reflection filter 4 is inserted inside the groove 3. The reflection filter 4 is installed at an angle θ substantially equal to the groove 3 with respect to the optical axis so as to include at least a portion through which the signal light transmitted through the optical waveguide 2 _n passes. The reflection filter 4 is preferably made of a dielectric multilayer filter so that a part of signal light of a predetermined wavelength (within a predetermined wavelength band) transmitted through the optical waveguide 2 _n is reflected at a constant reflectance. Is configured.

Further, the dielectric multilayer filter constituting the reflection filter 4 compensates for the difference in the reflectance between the orthogonal polarizations when the signal light is reflected, so that the signal light in each polarization state is compensated. The components are formed so as to be reflected with substantially the same reflectance. The setting of the reflectance for the signal light component in each polarization state is performed by, for example, the dielectric material of each layer constituting the dielectric multilayer filter, the combination thereof, the film thickness of each layer, and the like.

The inside of the groove 3 including the reflection filter 4 is sealed with a filling resin 5. Here, the filling resin 5 in the present embodiment seals a predetermined range on the upper surface of the optical planar waveguide type circuit 1 including the inner filling resin portion 51 sealing the inside of the groove 3 and the upper side of the groove 3. Upper filling resin portion 52
Consists of The internal filling resin portion 51 and the upper filling resin portion 52 are integrally formed using the same resin material.

A photodetector array having photodetectors 6 _n (n = 1 to 8) corresponding to the respective optical waveguides 2 _n is provided on the upper filling resin portion 52 of the filling resin 5 and on the upper surface side of the submount substrate 7. 6 are installed. The photodetector array 6 is configured so that a part of the signal light transmitted through the optical waveguide 2 _n is reflected by the reflection filter 4.
Are reflected by the corresponding photodetectors 6 _n
Are arranged so as to be incident on the light receiving surface. In addition,
As the light detector 6 _n , it is preferable to use a back-illuminated photodiode or the like from the incident direction of the reflected light.

In the above configuration, when the signal light transmitted through the optical waveguide 2 _n is emitted to the internal filling resin portion 51 in the groove 3 via the upstream end face 31, a part of the signal light is The light is reflected obliquely upward from the optical planar waveguide type circuit 1 by the reflection filter 4 inclined with respect to the optical axis, at a predetermined reflectance polarization-compensated so as to be equal for each polarization state. The other signal light components are supplied to the inner filling resin portion 5.
1 and the reflection filter 4 and enter the optical waveguide 2 _n again through the downstream end face 32.

On the other hand, the reflected light reflected by the reflection filter 4 is incident on the photodetector 6 _n via the internal filling resin portion 51, the optical waveguide 2 _n , and the upper filling resin portion 52. Then, based on the light intensity of the reflected light detected by the photodetector 6 _n , the light intensity of the signal light transmitted through the optical waveguide 2 _n is monitored.

In the optical waveguide module of the present embodiment, the optical waveguide itself is not branched by an optical component such as an optical coupler, but the signal light is not branched by the diagonal groove 3 provided across each optical waveguide 2 _n. The part is reflected and used for monitoring the light intensity. Thus, the configuration of the optical circuit in the optical waveguide module capable of monitoring the light intensity is simplified. In addition, since there is no need to install extra optical components or to splice each optical waveguide, the manufacturing process is similarly simplified.

The reflection of the signal light is controlled by the end faces 31 and 3 of the groove 3.
2, a part of the signal light is reflected by the reflection filter 4 which realizes the polarization compensation in which the reflectance between the orthogonal polarizations is substantially equal. At this time, since the reflectance of the signal light by the reflection filter 4 is substantially constant regardless of the polarization state of the signal light transmitted through the optical waveguide 2 _n , the reflection light detected by the photodetector 6 _n is Using the light intensity, the light intensity can be correctly monitored regardless of the polarization state of the signal light.

The inside of the groove 3 including the reflection filter 4 is sealed with a filling resin 5. At this time, groove 3
The end faces 31 and 32 and the reflection filter 4 do not come into contact with the outside air, so that long-term deterioration of operation stability due to their contamination is prevented.

Here, the inclination angle θ of the groove 3 and the reflection filter 4 with respect to the vertical axis is preferably within an angle range of 0 ° <θ ≦ 40 °.

FIG. 3 shows a polarization dependent loss (PDL: PoL) when the inclination of the reflecting surface with respect to the optical axis through which the signal light is transmitted is changed.
larization dependent loss). As shown in this graph, when the inclination angle θ with respect to the vertical axis is set to 0 ° (when the signal light is reflected in the opposite direction), the reflection characteristics of the ordinary reflection surface have no polarization dependence and PDL. =
It becomes 0. Then, as the tilt angle θ increases, the polarization dependence of the reflectance increases. When θ exceeds 40 °, the value of the PDL rapidly increases.

As described above, when θ increases and PDL increases, it becomes difficult to compensate for the polarization difference of the reflectance by the reflection filter 4. That is, in a configuration in which the inclination angle θ is large,
Since the value of PDL is large and changes abruptly due to θ, in a dielectric multilayer filter for compensating for the difference in reflectance, the numerical values required for the refractive index and film thickness of the material of each layer are required. Conditions become very strict. For this reason, it is practically difficult to design and create a dielectric multilayer filter of the reflection filter 4 so that the difference in reflectance is sufficiently compensated. On the other hand, when the inclination angle θ is 0 ° <θ ≦ 40 °
When the angle is within the range, compensation for the difference in the reflectance in the reflection filter 4 can be realized with sufficient accuracy.

The filling resin 5 is used for the optical waveguide 2
Refractive index substantially the same as _n core 20 (for example, within 1% error)
It is preferable to use a resin material having

When the internal filling resin portion 51 is made of a resin material having substantially the same refractive index as the core 20, a signal light is emitted from the optical waveguide _2n to the internal filling resin portion 51 (see FIG. 2). Extra reflection at point P1) is suppressed.
When the reflected light reflected by the reflection filter 4 is incident on the optical waveguide 2 _n from the internal filling resin portion 51 (point P2
Extra reflection) is suppressed.

Further, by making the upper filling resin 52 a resin material having substantially the same refractive index as that of the core 20, the reflected light reflected by the reflection filter 4 enters the upper filling resin portion 52 from the optical waveguide _2n. (See point P3), the extra reflection is suppressed.

The optical waveguide 2 _n and the internal filling resin portion 5
When extra reflection occurs at each interface between the first and upper filling resin portions 52, their reflection characteristics have polarization dependence depending on the respective reflection angles. Therefore, if the refractive index is not matched between these parts and the reflection occurs, the light is detected by the photodetector 6 _n despite the fact that the reflection filter 4 performs the polarization compensation of the difference in the reflectance. The light intensity of the reflected light is
This depends on the polarization state of the signal light. On the other hand, if the index of refraction is matched to suppress excess reflection at each interface, it is possible to reliably monitor the correct light intensity regardless of the polarization state of the signal light. Becomes

When an upper filling resin portion 52 is provided in addition to the inner filling resin portion 51 as in the present embodiment, these filling resin portions 51, 52 are substantially the same as each other. It is preferable to use a resin material having a refractive index. This makes it possible to control the extra reflection of the signal light (reflected light) at the interface of the upper filling resin portion 52 as well as the extra reflection of the signal light (reflected light) at the interface of the inner filling resin portion 51. Becomes

Further, the filling resin portions 51 and 52 may be formed integrally using the same resin material. This simplifies the step of filling the resin. In addition, core 2
The difference in refractive index between 0 and the upper cladding 21 is usually negligible for this reflection problem.

When the extraneous reflection when the light reflected by the reflection filter 4 is incident on the photodetector 6 _n from the upper filling resin portion 52 (see point P 4) becomes a problem, the filling is performed. the interface between the resin 5 and the light detector 6 _n, it is preferable to provide an antireflection coating. Thereby, the photodetector 6
extra reflection caused when the reflected light is incident from the reflection filter 4 to _n is suppressed, the optical and the waveguide 2 _n,
As with the extra reflection at each interface between the internal filling resin portion 51 and the upper filling resin portion 52, it is possible to reliably monitor a correct light intensity regardless of the polarization state of the signal light.

The photodetector 6 _n and the photodetector array 6
The configuration, the light receiving surface of each photodetector 6 _n, as shown in FIG. 1, a substantially elliptical shape to the optical axis direction of the optical waveguide 2 _n longitudinal axis, the array direction of the optical waveguide 2 _n and minor axis Is preferably formed.

FIG. 4 shows the shape of the light spot reflected by the light reflected by the reflection filter 4 and the light detector 6.
It is a schematic diagram for _{demonstrating} the light receiving surface shape of _n .
The signal light transmitted through the optical transmission line 2 _n has a substantially circular signal light spot due to the shape of the core 20 and the like. Therefore, the reflected light (see the side view in FIG. 4A) in which the signal light is reflected by the oblique reflection filter 4 is reflected by the photodetector 6 as shown by the dotted line A in the plan view in FIG. _An elliptical reflected light spot is formed on the light receiving surface of _n .

On the other hand, the light receiving surface of the photodetector 6 _n is
As shown by the solid line B in FIG. 4B, if the light spot is formed into a substantially elliptical shape including the reflected light spot and along the elliptical shape of the reflected light spot, the reflected light can be detected with sufficient light receiving efficiency. Can be. In addition, it is possible to converge the elliptical reflected light by using a lens or the like and make it incident on the photodetector. However, in this case, the number of optical components increases, resulting in high cost. On the other hand, _if the shape of the light receiving surface of the photodetector 6 _n is made substantially elliptical in accordance with the reflected light spot, the configuration of the optical waveguide module can be simplified and the cost can be reduced.

Here, when the light receiving surface has a circular shape as shown by a solid line C in FIG. 4C, the light receiving efficiency of the reflected light is not different from that in the case of a substantially elliptical shape. array direction of the light detector corresponds to (6 see _{1-6 8} in FIG. 1)
, The width of the light receiving surface becomes large. For this reason, in the photodetector array, the photodetectors cannot be integrated at a high density with a small arrangement pitch, and the optical circuit increases in area and cost.

On the other hand, if the light receiving surface has a substantially elliptical shape, the arrangement pitch of the photodetectors can be made as small as possible, and an optical circuit can be efficiently formed.

When the light receiving surface is formed in a rectangular shape as shown by a solid line D in FIG. 4D, photodetectors can be integrated at the same arrangement pitch as in the case of a substantially elliptical shape. However, in this configuration, an unnecessary light receiving surface portion that is not used for receiving reflected light occurs in a diagonal direction of the light receiving surface. Since such a light receiving surface portion is a source of noise for the light detection signal, it causes a reduction in the efficiency of reflected light detection, such as deterioration of the S / N ratio and a reduction in the effective dynamic range. Such a problem also applies to the above-described circular light receiving surface shape.

On the other hand, if the light receiving surface has a substantially elliptical shape, it is possible to reduce the occurrence of noise and the like from unnecessary light receiving surfaces, and to improve the efficiency of light intensity monitoring. . However, a circular or rectangular light-receiving surface shape may be used depending on the arrangement pitch, detection efficiency, and the like required for each optical waveguide module.

A specific example of the optical waveguide module according to the above embodiment will be described.

First, a first embodiment will be described. In this embodiment, the groove 3 was formed with an inclination angle of θ = 30 ° and a width w = 25 μm with respect to the optical axis direction. As the reflection filter 4 inserted inside the groove 3, a polarization compensation filter having a reflectivity of 10% for signal light and a thickness of 11 μm was used.
As the filling resin 5, the same resin material was used for the inner filling resin portion 51 and the upper filling resin portion 52. The refractive index of the refractive index matching adhesive, which is a resin material used, has a wavelength of 1.5
N = 1.47 in the band of 1 μm to 1.61 μm. As the photodetector 6 _n , an InGaAs-PIN photodiode having an elliptical light-receiving surface having a major axis diameter of 0.3 mm and a minor axis diameter of 0.15 mm was used. The light receiving sensitivity of this photodiode alone was 1.1 A / W.

When the light intensity of the signal light was monitored using the optical waveguide module having the above configuration, the polarization dependence of the reflectance of the reflection filter 4 was 10% for the S polarization,
When the P polarization is 10.3%, the polarization dependent loss PDL is 0.1%.
It was confirmed that the light intensity could be monitored in a state where the signal light was sufficiently small as dB and the dependence of the signal light on the polarization state was sufficiently reduced.

The light receiving sensitivity to the incident signal light was about 0.1 A / W. This indicates that the light intensity of the signal light component reflected by the reflection filter 4 at a reflectance of 10% is detected by the photodetector 6 _{n with an} efficiency close to 100%. The insertion loss of the groove 3 and the reflection filter 4 into the optical waveguide 2 _n is approximately 1.0 dB, including the reflection of the signal light by the reflection filter 4 and the loss due to the diffraction of the signal light inside the groove 3. Met.

Next, a second embodiment will be described. In this example, the groove 3 was formed with an inclination angle of θ = 10 ° and a width w = 25 μm with respect to the optical axis direction. As the reflection filter 4 inserted inside the groove 3, a polarization compensation filter having a reflectivity of 10% for signal light and a thickness of 11 μm was used.
As the filling resin 5, the same resin material was used for the inner filling resin portion 51 and the upper filling resin portion 52. The refractive index of the refractive index matching adhesive, which is a resin material used, has a wavelength of 1.5
N = 1.47 in the band of 1 μm to 1.61 μm. As the photodetector 6 _n , a photodiode having an elliptical light-receiving surface with a diameter in the major axis direction of 0.3 mm and a minor axis direction of 0.15 mm was used. The light receiving sensitivity of this photodiode alone was 1.1 A / W.

In this embodiment, the photodetector 6 _n
An anti-reflection coating is provided on the interface between the upper filling resin 52 and the photodetector 6 _n in order to prevent extra reflection caused when reflected light is incident on the photo detector 6 _n .

When the light intensity of the signal light was monitored using the optical waveguide module having the above configuration, the polarization dependence of the reflectance at the reflection filter 4 was found to be S polarization 9.7.
%, P polarization 10%, and polarization dependent loss PDL 0.1
It was confirmed that the light intensity could be monitored in a state where the signal light was sufficiently small as dB and the dependence of the signal light on the polarization state was sufficiently reduced.

The light receiving sensitivity to the incident signal light was about 0.1 A / W. This indicates that the light intensity of the signal light component reflected by the reflection filter 4 at a reflectance of 10% is detected by the photodetector 6 _{n with an} efficiency close to 100%. The insertion loss of the groove 3 and the reflection filter 4 into the optical waveguide 2 _n is approximately 1.0 dB, including the reflection of the signal light by the reflection filter 4 and the loss due to the diffraction of the signal light inside the groove 3. Met.

From the first and second embodiments described above, the optical waveguide module having the above-described configuration realizes an optical waveguide module capable of correctly monitoring the light intensity regardless of the polarization state of the signal light. You can see that it is.

An embodiment of the optical waveguide module according to the present invention will be further described.

FIG. 5 is a plan view showing the configuration of the second embodiment of the optical waveguide module. The optical waveguide module, as in the first embodiment, is configured to have an optical waveguide 2 ₁ to 2 ₈ substrate 10, and eight planar waveguide formed on the substrate 10 (8 channels) Optical planar waveguide type circuit 1.

[0070] Each of the optical waveguide 2 ₁ to 2 _8, along a predetermined optical transmission direction (the direction of the arrow in FIG. 5), with the input end 11 of the optical planar waveguide circuit 1 towards the output end 12 Are formed parallel to each other and at equal intervals. Further, the predetermined site for the optical transmission direction of the optical planar waveguide circuit 1, are provided grooves 3 crossing the optical waveguide 2 ₁ to 2 _8.

[0071] The groove 3, the optical waveguides 2 ₁ - on the inside thereof
With 2 ₈ reflection filter 4 for reflecting a portion of the transmitted signal light is installed, it is sealed by filling resin 5. Further, above the optical planar waveguide circuit 1 at a position upstream of the groove 3, a photodetector having eight light detectors 61 ₁ to 61 ₈ respectively corresponding to the optical waveguide 2 ₁ to 2 ₈ An array 60 is provided. Incidentally, in FIG. 5, the light detector 61 _{1-61 8} illustrates the shape of each of the light receiving surface by a dotted line.

FIG. 6 is a sectional view showing the sectional structure of the optical waveguide module shown in FIG. 5 along the optical axis direction of the optical waveguide 2 _n (n = 1 to 8). In FIG. 6, a portion including the groove 3, the reflection filter 4, and the photodetector array 60 is shown in an enlarged manner. 6, the optical planar waveguide type circuit 1 including the optical waveguide 2 _n including the lower clad 22, the core 20, and the upper clad 21, the groove 3, and the reflection filter 4 are shown in FIG. This is the same as the configuration shown.

The inside of the groove 3 including the reflection filter 4 is sealed with the filling resin 5. Here, the filling resin 5 in the present embodiment includes only the internal filling resin portion 51 that seals the inside of the groove 3.

The upper cladding 21 of the optical planar waveguide type circuit 1
The photodetector array 60 having photodetectors 61 _n (n = 1 to 8) respectively corresponding to the respective optical waveguides 2 _n is provided on the upper surface side of the photodetector array 60.
Is installed. The photodetector array 60 includes the optical waveguide 2
reflected light part of the signal light transmitted through _n is reflected by the reflection filter 4 is disposed so as to be respectively incident to the light receiving surface of the corresponding photodetector 61 _n. Note that it is preferable to use a back-illuminated photodiode or the like as the photodetector 61 _n from the incident direction of the reflected light. Also, the photodetector 61 _n and the upper clad 21 of the optical waveguide 2 _n
An anti-reflection coat may be provided at the interface with.

In the above configuration, when the signal light transmitted through the optical waveguide 2 _n is emitted to the internal filling resin portion 51 in the groove 3 via the upstream end face 31, a part of the signal light is The light is reflected obliquely upward from the optical planar waveguide type circuit 1 by the reflection filter 4 inclined with respect to the optical axis, at a predetermined reflectance polarization-compensated so as to be equal for each polarization state. The other signal light components are supplied to the inner filling resin portion 5.
1 and the reflection filter 4 and enter the optical waveguide 2 _n again through the downstream end face 32.

On the other hand, the light reflected by the reflection filter 4
The reflected light is reflected by the internal filling resin portion 51 and the optical waveguide 2._nThrough
And the photodetector 61_nIncident. And light detection
Container 61 _nFrom the light intensity of the reflected light detected in_n
The light intensity of the signal light being transmitted through is monitored.

In the optical waveguide module according to the present embodiment,
As in the first embodiment, each optical waveguide 2 _nAcross the
A part of the signal light is reflected by the
And is used to monitor the light intensity. This allows the light intensity
Of optical circuit in optical waveguide module capable of monitoring temperature
Is simplified. Installation of extra optical components and light guide
Since the fusion splicing of the wave path becomes unnecessary, the manufacturing process is the same.
Simplified.

Further, since a part of the signal light is reflected by the reflection filter 4 which realizes the polarization compensation in which the reflectance between the orthogonal polarizations is substantially equal, the reflection detected by the photodetector 61 _n is obtained. Using the light intensity of the light, the light intensity can be correctly monitored regardless of the polarization state of the signal light. Further, since the inside of the groove 3 including the reflection filter 4 is sealed with the filling resin 5, the end surfaces 31, 32 of the groove 3 and the reflection filter 4 do not come into contact with the outside air, and a long-term due to their contamination. The deterioration of the operational stability is prevented.

Here, as in the above-described first and second embodiments, the optical planar waveguide circuit 1 has N (N is plural, N = 8 in the above-described embodiment) optical waveguides. When monitoring the light intensity of the N-channel signal light transmitted through the optical waveguides, N photodetectors are provided so as to correspond to each optical waveguide. Then, the N-channel signal light reflected by the reflection filter propagates through a predetermined reflection optical path and is detected by a corresponding photodetector, so that the light intensity of each signal light is monitored.

At this time, while the signal light from the optical waveguide reflected by the reflection filter is detected by the corresponding photodetector, light scattering and reflection occurring at various parts of the device, spread of transmitted light, etc. Therefore, there is a problem of crosstalk in which a part of the light is incident on a photodetector of an adjacent other channel and is detected. When crosstalk occurs between adjacent channels as described above, it becomes impossible to accurately monitor the light intensity of the signal light in each channel.

There are several possible causes of such crosstalk between channels. For example, in the configuration shown in FIG. 2 or FIG. 6, irregular reflection at the interface between each part of the optical planar waveguide circuit 1 and the
Scattered light due to defects on the upper surface of the substrate 1 and reflected light or scattered light due to irregular reflection at the interface between the substrate 10 and the lower clad 22 are considered as causes of crosstalk.

The signal light transmitted through the optical waveguide mainly propagates in the core, but a part of the signal light also propagates in the upper and lower cladding near the core. At this time,
If the signal light spreads too much to the cladding, the reflected light path from the reflection filter to the photodetector will be excessively wide, and unnecessary scattered light will be generated in the optical waveguide or the like, causing crosstalk.

The spread of the signal light to the clad also occurs due to, for example, misalignment of the signal light input optical fiber connected to the input end of the optical planar waveguide circuit with respect to the optical waveguide. That is, when the optical fiber is connected to a position shifted from the core of the optical waveguide,
The input signal light propagates in a clad having no waveguide structure.

In order to deal with such a problem of crosstalk between channels, in the second embodiment in which the photodetector array 60 is directly installed on the upper surface side of the optical planar waveguide type circuit 1 without providing a submount substrate or the like. As shown in FIG. 6, the reflected light path from the reflection filter 4 to the photodetector 61 _n is shortened, and the spread of the reflected light can be reduced. In addition, the influence of irregular reflection and scattering inside or at the interface of the filling resin 5 or the optical waveguide 2 _n is reduced. Therefore, occurrence of crosstalk between channels is suppressed.

Further, in any of the first and second embodiments, the effect of confining the signal light into the core 20 with respect to the signal light transmitted through the optical waveguide 2 _n is increased by the crosstalk. It is preferable in preventing occurrence. Specifically, the refractive index difference Δn between the core 20 and the clads 21 and 22
Is preferably increased. Thereby, the spread of the signal light propagated in the core 20 to the claddings 21 and 22 can be reduced. In addition, the effect of confining light inside the core can be expected for the signal light component that has permeated into the clad due to misalignment of the optical fiber or the like because the core has a high refractive index.

As an example, in the configuration shown in FIG. 6, the refractive index difference Δn between the core 20 and the claddings 21 and 22 is 0.3n.
%, When an optical fiber was connected to an optical waveguide having a core size of 8.5 μm square and misaligned at a position offset by 2 μm from the core, the crosstalk was degraded to −22 dB. In contrast, the refractive index difference Δ
When n was increased from 0.3% to 0.45%, <-
Crosstalk was improved to a level of 25 dB.

Here, a method of manufacturing an optical planar waveguide type circuit when the refractive index difference Δn between the core and the clad is increased will be described. The core and the upper cladding (overcladding) are formed, for example, by subjecting a SiO ₂ (quartz) glass fine powder to which a predetermined additive is added, to a flame deposition method (FHD method: Flame Hydrolysis Deposition Metho).
It is formed by depositing and sintering according to d).

Specifically, for example, the core is made of Ge-added Si
The O ₂ glass and the upper clad are made of B / P added SiO ₂ glass. Ge, B, P, and SiO ₂ are each GeC
Hydrolysis of l ₄ , BCl ₃ , POCl ₃ , and SiCl ₄ in an oxyhydrogen burner gives a soot-like fine powder. By adjusting the amount of Ge added to the core and the amounts of B and P added to the upper clad, the refractive index difference Δn
Is adjusted.

For example, typically, the amount of Ge added to the core is Ge concentration = 3.2 w when Δn = 0.3%.
Ge concentration = 4.6 wt% when t% and Δn = 0.45%
%. The addition amount of B and P to the upper clad is determined by the sooting conditions and the like. However, the addition amount of P for increasing the refractive index and the addition amount of B for decreasing the refractive index are balanced, and pure SiO ₂ Adjust so as to have the same refractive index as glass. By the above method, the refractive index difference Δn between the core and the upper clad is 0.3%, 0.4
An optical waveguide of 5% is obtained.

In order to solve the problem of crosstalk between channels described above, it is effective to provide an optical path isolating means between optical paths, in addition to increasing the effect of confining light in the core. That is, by providing the optical path isolation means between the adjacent reflected light paths, it is possible to minimize the occurrence of crosstalk between the adjacent channels. This makes it possible to more accurately monitor the light intensity of the signal light in each channel of the N-channel signal light transmitted through each optical waveguide.

FIG. 7 is a plan view showing the configuration of the third embodiment of the optical waveguide module. The optical waveguide module, as in the first embodiment, is configured to have an optical waveguide 2 ₁ to 2 ₈ substrate 10, and eight planar waveguide formed on the substrate 10 (8 channels) Optical planar waveguide type circuit 1.

[0092] Each of the optical waveguide 2 ₁ to 2 _8, along a predetermined optical transmission direction (a direction indicated by an arrow in FIG. 7), and from the input end 11 of the optical planar waveguide circuit 1 towards the output end 12 Are formed parallel to each other and at equal intervals. Further, the predetermined site for the optical transmission direction of the optical planar waveguide circuit 1, are provided grooves 3 crossing the optical waveguide 2 ₁ to 2 _8.

[0093] The groove 3, the optical waveguides 2 ₁ - on the inside thereof
With 2 ₈ reflection filter 4 for reflecting a portion of the transmitted signal light is installed, it is sealed by filling resin 5. Further, above the optical planar waveguide circuit 1 at a position upstream of the groove 3, a photodetector having eight light detectors 63 ₁ to 63 ₈ respectively corresponding to the optical waveguide 2 ₁ to 2 ₈ An array 62 is provided.

In FIG. 7, the photodetector array 6
Together showing an optical planar waveguide type circuit 1 or the like in a state excluding the 2, to show the positional relationship between the photodetector array 62 of each part, the photodetector array 62 and light detector 63 _{1-63 8} dashed line Is shown in FIG.

[0095] In this embodiment, a portion of the signal light transmitted through each optical waveguide 2 ₁ to 2 ₈ 8-channel,
The corresponding photodetectors 63 _{1 to} 63 ₈ by the reflection filter 4
Optical path isolating means for isolating the reflected light paths is provided in the optical planar waveguide circuit 1 between the eight reflected light paths which are reflected from the optical path. . This optical path isolation means is for suppressing the occurrence of crosstalk between adjacent channels.

[0096] Specifically, in the present embodiment, in the optical planar waveguide circuit 1, so as to shield light passing into the reflection optical path adjacent the reflection optical path, the optical waveguide 2 ₁ 8
Light-shielding layer 25 is provided between the to 2 _8, respectively.

That is, the optical waveguide 2₁And 2_TwoBetween the light guide
Wave path 2_TwoAnd 2_ThreeBetween the optical waveguide 2_ThreeAnd 2_FourBetween the optical waveguide
Road 2_FourAnd 2_FiveBetween the optical waveguide 2_FiveAnd 2₆Between the optical waveguide
2₆And 2₇And the optical waveguide 2₇And 2₈Between, it
Each of the light shielding layers 25₁, 25 _Two, 25_Three, 25_Four, 25_Five,
25₆, And 25₇Is provided.

[0098] In this third configuration of an optical waveguide module in the embodiment, except the above light-shielding layer 25 _to 253 ₇ provided in the optical planar waveguide circuit 1, 5 and 6
Is similar to the second embodiment shown in FIG.

FIG. 8 is a cross-sectional view of the optical waveguide module shown in FIG. 7 taken along the line II along the direction perpendicular to the optical axis of the optical waveguide 2 _n (n = 1 to 8). . Incidentally, in FIG. 8, the optical waveguide 2 _{3-2 5,} the light shielding layer 25 ₂
25 _5, and while expanding the portion including the optical detector 63 _{3-63 5,} shown is shown a section through the respective center positions of the photodetector 63 _{3-63 5} (in FIG. 6 by dotted lines cross (See position B).

[0100] Light planar waveguide circuit 1, as shown in FIG. 8, substrate 10 and the lower clad 22 formed on the optical waveguide 2 ₁ formed in parallel at equal intervals from each other on the lower clad 22 ~ and eight cores 20 corresponding to 2 _8, consists of eight cores 20 (optical waveguide 2 ₁ to 2 ₈₎ upper clad 21 formed so as to cover the entire. Above the upper cladding 21, a photodetector array 62 comprising a photodetector 63 _{1-63 8} is installed.

[0102] In the present embodiment, the upper cladding 21 located between the optical waveguide 2 ₁ to 2 ₈ are each removed by a predetermined width x1, the site upper cladding 21 is removed, the light Light shielding layer 25 _{1 to} 25 _{7 for} shielding
Is provided. These light-shielding layer 25 _to 253 _7,
As shown in FIG. 7, it is formed over a range of a predetermined length 11 across the groove 3.

[0102] In the above configuration, focusing the signal light of the fourth channel transmitted from the optical waveguide 2 _4, the signal light transmitted through the optical waveguide 2 _4, the upstream end face 31
(See FIG. 6), a part of the signal light is equalized for each polarization state by the reflection filter 4 oblique to the optical axis. The light is reflected obliquely upward from the optical planar waveguide circuit 1 at a predetermined reflectance whose polarization has been compensated for. The signal light components other than it is transmitted through the inner filling resin portion 51 and the reflective filter 4, it is incident again to the optical waveguide 2 ₄ via the downstream end face 32.

On the other hand, the light reflected by the reflection filter 4
The reflected light is reflected by the internal filling resin portion 51 and the optical waveguide 2._FourThrough
And the photodetector 63_FourIncident. And light detection
Bowl 63 _FourFrom the light intensity of the reflected light detected in_Four
The light intensity of the fourth channel signal light transmitted
I will be messed up.

[0104] Further, the optical waveguide 2 ₄ viewed from of the light-waveguide 2 ₃ and the light detector 63 ₃ side of the upper clad 21, the light shielding layer 25 ₃ is provided. With this light shielding layer 25 ₃ ,
Of the signal light being transmitted through the optical waveguide 2 _4, scattering of light, reflection, light is propagated to the photodetector 63 ₃ adjacent the like spread of light to be transmitted is blocked, third, fourth The occurrence of crosstalk between channels is prevented.

[0105] Further, the optical waveguide 2 ₄ viewed from of the light-waveguide 2 ₅ and the photodetector 63 ₅ side of the upper clad 21, the light shielding layer 25 ₄ is provided. The light-shielding layer 25 _4,
Of the signal light being transmitted through the optical waveguide 2 _4, scattering of light, reflection, light is propagated to the photodetector 63 ₅ adjacent the like spread of light to be transmitted is blocked, fourth, fifth The occurrence of crosstalk between channels is prevented.

In this embodiment, the reflected light path from the reflection filter 4 to the photodetectors 63 _{1 to} 63 ₈ is provided as an optical path isolating means for separating the reflected light paths in the optical planar waveguide type circuit 1. is provided a shielding layer 25 _to 253 _7. Thereby, as described above, it is possible to reliably prevent the occurrence of crosstalk between adjacent channels.

[0107] As the light-shielding layer 25 _to 253 ₇ provided on the optical planar waveguide circuit 1, absorb light in the signal light wavelength, the light shielding having the effect of shielding the light by reflecting or scattering such It is preferable to use a material. Specifically, for example, glass to which an additive having a light absorbing effect such as Ge (germanium) is added at a high concentration can be used as the light shielding material.

[0108] Further, as a method for forming the light-shielding layer 25 _to 253 _7, for example, as shown in FIGS. 7 and 8, across the grooves 3 between the eight optical waveguides 2 ₁ to 2 ₈ each There is a method in which seven grooves each having a width x1 and a length 11 are formed substantially parallel to the optical waveguide, and the inside of the grooves is filled with a light shielding material.
Further, the light-shielding layer 25 _to 253 ₇ each having a width x1, length l
Regarding 1, it is preferable to set so that the reflected light path from the reflection filter 4 to the photodetector 63 _n is not excessively narrowed, and the light shielding effect between adjacent channels is sufficiently ensured. . Alternatively, a configuration may be adopted in which a light shielding layer is provided on the entire optical waveguide type circuit 1 from the input end 11 to the output end 12.

As an example, by providing a light shielding layer in the upper cladding of the optical planar waveguide type circuit as described above for the state where the crosstalk has been degraded to -22 dB.
Crosstalk was improved to levels of <-30 dB.
Further, even when the light shielding layer is not filled with a substance, the scattered light is suppressed to some extent, so that an effect of improving crosstalk can be obtained. For example, −22 dB is improved to −28 dB.

FIG. 9 is a plan view showing the structure of the fourth embodiment of the optical waveguide module. The optical waveguide module, as in the first embodiment, is configured to have an optical waveguide 2 ₁ to 2 ₈ substrate 10, and eight planar waveguide formed on the substrate 10 (8 channels) Optical planar waveguide type circuit 1.

[0111] Each of the optical waveguide 2 ₁ to 2 _8, along a predetermined optical transmission direction (a direction indicated by an arrow in FIG. 9), and from the input end 11 of the optical planar waveguide circuit 1 towards the output end 12 Are formed parallel to each other and at equal intervals. Further, the predetermined site for the optical transmission direction of the optical planar waveguide circuit 1, are provided grooves 3 crossing the optical waveguide 2 ₁ to 2 _8.

[0112] The groove 3, the optical waveguides 2 ₁ - to the inside
With 2 ₈ reflection filter 4 for reflecting a portion of the transmitted signal light is installed, it is sealed by filling resin 5. A submount substrate 70 is installed above the optical planar waveguide type circuit 1 at a position upstream of the groove 3, and the filling resin 5 and the submount substrate 7 are provided.
Above 0, respectively corresponding to the optical waveguide 2 ₁ to 2 ₈ 8
Photodetector array 64 having a number of light detectors 65 ₁ to 65 ₈
Is installed.

In FIG. 9, the photodetector array 6
4 shows the optical planar waveguide type circuit 1 and the submount substrate 70, etc., and the photodetector array 6 of each part.
For showing a positional relationship between the 4 and the photodetector array 64 and light detector 65 _{1-65 8} illustrated by one-dot chain line. Also,
The submount substrate 70 is a mounting member (mounting member) on which the photodetector array 64 is mounted, and has a photodetector 65 on its upper surface, as schematically shown in FIG. wirings, electrodes, etc. for reading the light detection signal from _{1-65 8} is formed.

[0114] In this embodiment, a portion of the signal light transmitted through each optical waveguide 2 ₁ to 2 ₈ 8-channel,
The corresponding photodetectors 65 _{1 to} 65 ₈ by the reflection filter 4
Light path isolating means for isolating the reflected light paths from each other is provided in the filling resin 5 between the eight reflected light paths. This optical path isolation means is for suppressing the occurrence of crosstalk between adjacent channels.

Specifically, in this embodiment, the filling resin 5
Are filled so as to seal a predetermined area on the upper surface of the optical planar waveguide circuit 1 including the upper side of the groove in addition to the inside of the groove 3. Then, a light shielding portion is provided on the submount substrate 70 located on the upstream side of the upper filling resin portion for sealing the upper surface of the optical planar waveguide type circuit 1 so as to protrude into the upper filling resin portion in a comb shape. 71 _{1-71 7} is provided.

[0116] That is, when viewed in correspondence with the optical waveguide 2 ₁ to 2 ₈ in the optical planar waveguide circuit 1, the optical waveguide 2 ₁ and 2 ₂
Between, between the optical waveguide 2 ₂ and 2 _3, between the optical waveguide 2 ₃ between 2 _4, between the optical waveguide 2 ₄ and 2 _5, the optical waveguide 2 ₅ and 2 _6, the optical waveguide 2 ₆ and between 2 ₇ and between the optical waveguide 2 ₇ 2 _8, respectively, the light shielding portion 71 _1, 71 _2, 71 _3, 7
1 _4, 71 _5, 71 _6, and 71 ₇ are provided.

[0117] Note that the structure of the optical waveguide module in the fourth embodiment, except for the above light-shielding portion 71 _{1-71 7} provided on the submount substrate 70, FIGS. 1 and 2
This is the same as the first embodiment shown in FIG.

FIG. 10 is a cross-sectional view of the optical waveguide module shown in FIG. 9 taken along the line II-II shown in the direction perpendicular to the optical axis of the optical waveguide 2 _n (n = 1 to 8). . Incidentally, in this FIG. 10, the optical waveguide 2 _{3-2 5,} the light shielding portion 71 _{2-71 5,} and while expanding the portion including the optical detector 65 _{3-65 5,} the photodetector 65 _{3-65 5} Are shown (see cross-sectional position A indicated by a dotted line in FIG. 2).

[0119] Light planar waveguide circuit 1, as shown in FIG. 10, the substrate 10 and the lower clad 22 formed on the optical waveguide 2 ₁ formed in parallel at equal intervals from each other on the lower clad 22 ~ and eight cores 20 corresponding to 2 _8, consists of eight cores 20 (optical waveguide 2 ₁ to 2 ₈₎ upper clad 21 formed so as to cover the entire.

On the upper surface side of the upper cladding 21, there is provided an upper filling resin portion 52 which is a portion of the filling resin 5 which seals a predetermined range of the upper surface of the optical planar waveguide circuit 1 (see FIG. 1). (See FIG. 2). The upper filling resin portion 52 has substantially the same height as the submount substrate 70. Above the upper filling resin portion 52 and the submount substrate 70, the photodetector array 64 including a light detector 65 _{1-65 8} is installed. However, the lower portion A of the photodetector 65 _{1-65 8} photodetector array 64, the light from the reflection filter 4 has an upper filling resin portion 52 can pass.

[0121] Then, in this embodiment, with respect to the upper filling resin portion 52 at a position corresponding to between the optical waveguide 2 ₁ to 2 ₈ (between the photodetector 65 _{1-65 8),} the sub-mount substrate 70 the end face which is in contact with the upper filling resin portion 52, each comb-shaped light shielding portions 71 ₁ to 71 ₇ are formed in a predetermined width x2 is provided for. Light-shielding portion 71 _{1-71 7} has a structure in which each protruding to the upper filling resin portion 52 on the downstream side of the submount substrate 70. Further, these light-shielding portion 71 _{1-71 7,} as shown in FIG. 9, a predetermined length l2
Is formed over the range.

[0122] In the above configuration, focusing the signal light of the fourth channel transmitted from the optical waveguide 2 _4, the signal light transmitted through the optical waveguide 2 _4, the upstream end face 31
(See FIG. 2), a part of the signal light is equalized for each polarization state by the reflection filter 4 inclined with respect to the optical axis. The light is reflected obliquely upward from the optical planar waveguide circuit 1 at a predetermined reflectance whose polarization has been compensated for. The signal light components other than it is transmitted through the inner filling resin portion 51 and the reflective filter 4, it is incident again to the optical waveguide 2 ₄ via the downstream end face 32.

[0123] On the other hand, the light reflected by the reflection filter 4, inside the filling resin 51, the optical waveguide 2 _4, and via the upper filling resin portion 52, is incident on the photodetector 65 _4. Then, the light intensity of the reflected light detected by the photodetector 65 _4, the light intensity of the signal light of the fourth channel being transmitted through the optical waveguide 2 ₄ is monitored.

[0124] Also, in the optical waveguide 2 ₄ viewed from of the light-waveguide 2 ₃ and the light detector 65 ₃ side of the upper filler resin part 52, the light shielding portion 71 ₃ is provided. The optical shielding part 71 _3, out of the signal light being transmitted through the optical waveguide 2 _4, light scattering, reflection, light is propagated to the photodetector ₆₅₃ which is adjacent the like spread of the light transmitted Shielded, third,
The occurrence of crosstalk between the fourth channels is prevented.

[0125] Further, the optical waveguide 2 ₄ viewed from of the light-waveguide 2 ₅ and the photodetector 65 ₅ side of the upper filler resin part 52, the light shielding portion 71 ₄ are provided. The light shielding portion 71 _4, of the signal light being transmitted through the optical waveguide 2 _4, scattering of light, reflection, light is propagated to the photodetector 65 ₅ adjacent the like spread of the light transmitted Shielded, fourth,
The occurrence of crosstalk between the fifth channels is prevented.

[0126] In this embodiment, the reflective filter to 4 from the reflected light path of the optical detector 65 _{1-65 8,} the upper filling resin portion 52 of the filling resin 5, the optical path isolation means for isolating the reflected light path between the light shielding portion 71 _{1-71 7} is provided as. Thereby, as described above, it is possible to reliably prevent the occurrence of crosstalk between adjacent channels.

[0127] The submount substrate 70 the light shielding portion 71 _{1-71 7} provided so as to protrude into the filling resin 5 to shield light by the light of the signal light wavelength absorption, reflection, or scattering effects It is preferable to use a light shielding material having Specifically, for example, alumina or the like can be used as the light shielding material.

When the light shielding portions 71 _{1 to} 71 ₇ are formed integrally with the submount substrate 70 as described above, for example,
The submount substrate 70 itself is formed of a light shielding material. In addition, the width x2 and length l2 of each of the light shielding portions 71 _{1 to} 71 _7.
It is preferable to set a value such that the reflected light path from the reflection filter 4 to the photodetector 65 _n is not excessively narrowed, and that the light shielding effect between adjacent channels is sufficiently ensured.

As an example, when the crosstalk is degraded to −22 dB, by providing the light shielding portion in the upper filling resin portion of the filling resin as described above, the value of −23 dB is obtained.
Crosstalk was improved to the level of dB.

FIG. 11 is a plan view showing the configuration of the fifth embodiment of the optical waveguide module. This optical waveguide module includes a substrate 10 and a substrate 10 similar to the first embodiment.
A waveguide 2 ₁ to 2 ₈ eight planar waveguide formed on the upper (8 channels) and a composed optical planar waveguide circuit 1.

[0131] Each of the optical waveguide 2 ₁ to 2 _8, along a predetermined optical transmission direction (the direction of the arrow in FIG. 11), and from the input end 11 of the optical planar waveguide circuit 1 towards the output end 12 ,
They are formed parallel and at equal intervals. Further, the predetermined site for the optical transmission direction of the optical planar waveguide circuit 1, are provided grooves 3 crossing the optical waveguide 2 ₁ to 2 _8.

The grooves 3 are provided inside each of the optical waveguides 2 ₁ to 2.
With 2 ₈ reflection filter 4 for reflecting a portion of the transmitted signal light is installed, it is sealed by filling resin 5. In addition, a submount substrate 72 is provided above the optical planar waveguide type circuit 1 at a position upstream of the groove 3, and the filling resin 5 and the submount substrate 7 are provided.
The second upper, respectively corresponding to the optical waveguide 2 ₁ to 2 ₈ 8
Photodetector array 66 having a number of light detectors 67 ₁ to 67 ₈
Is installed.

FIG. 11 shows the optical planar waveguide type circuit 1 and the submount substrate 72, etc., without the photodetector array 66, and shows the positional relationship of each part with the photodetector array 66. Therefore, the photodetector array 66 and light detector 67 _{1-67 8} illustrated by one-dot chain line. The submount substrate 72 is a mounting member (mounting member) on which the photodetector array 66 is mounted, and has a photodetector on its upper surface, as schematically shown in FIG. vessel 67 ₁ wirings, electrodes, etc. for reading the light detection signal from -67 ₈ is formed.

[0134] In this embodiment, a portion of the signal light transmitted through each optical waveguide 2 ₁ to 2 ₈ 8-channel,
The corresponding photodetectors 67 _{1 to} 67 ₈ by the reflection filter 4
Optical path isolating means for isolating the reflected light paths is provided in the optical planar waveguide circuit 1 between the eight reflected light paths which are reflected from the optical path. . This optical path isolation means is for suppressing the occurrence of crosstalk between adjacent channels.

[0135] Specifically, in the present embodiment, in the optical planar waveguide circuit 1, so as to shield light passing into the reflection optical path adjacent the reflection optical path, the optical waveguide 2 ₁ 8
Light-shielding layer 26 is provided between the to 2 _8, respectively.

That is, the optical waveguide 2₁And 2_TwoBetween the light guide
Wave path 2_TwoAnd 2_ThreeBetween the optical waveguide 2_ThreeAnd 2_FourBetween the optical waveguide
Road 2_FourAnd 2_FiveBetween the optical waveguide 2_FiveAnd 2₆Between the optical waveguide
2₆And 2₇And the optical waveguide 2₇And 2₈Between, it
Each of the light shielding layers 26₁, 26 _Two, 26_Three, 26_Four, 26_Five,
26₆, And 26₇Is provided.

[0137] Note that the structure of the optical waveguide module in the fifth embodiment, except for the above light-shielding layer 26 _{1-26 7} provided in the optical planar waveguide circuit 1, FIGS. 1 and 2
This is the same as the first embodiment shown in FIG.

[0138] Figure 12 is a cross-sectional structure of the optical waveguide module shown in FIG. 11, is a III-III arrow sectional view taken along a direction perpendicular to the optical axis of the optical waveguide 2 _{n (n} = 1~8) .
Incidentally, in this FIG. 12, the optical waveguide 2 _{3-2 5,} the light shielding layer 26 _{2-26 5,} and while expanding the portion including the optical detector 67 _{3-67 5,} the photodetector 67 _{3-67 5} Are shown (see cross-sectional position A indicated by a dotted line in FIG. 2).

[0139] Light planar waveguide circuit 1, as shown in FIG. 12, the substrate 10 and the lower clad 22 formed on the optical waveguide 2 ₁ formed in parallel at equal intervals from each other on the lower clad 22 ~ and eight cores 20 corresponding to 2 _8, consists of eight core 20 (optical waveguide 2 ₁ to 2 ₈₎ upper clad 21 formed so as to cover the entire.

On the upper surface side of the upper cladding 21, there is provided an upper filling resin portion 52 which is a portion of the filling resin 5 which seals a predetermined range of the upper surface of the optical planar waveguide circuit 1 (see FIG. 1). (See FIG. 2). The upper filling resin portion 52 has substantially the same height as the submount substrate 72. Above the upper filling resin portion 52 and the sub-mount substrate 72, the photodetector array 66 including a light detector 67 _{1-67 8} is installed. However, the lower portion A of the photodetector 67 _{1-67 8} photodetector array 66, the light from the reflection filter 4 has an upper filling resin portion 52 can pass.

[0141] In the present embodiment, the upper cladding 21 located between the optical waveguide 2 ₁ to 2 ₈ are each removed by a predetermined width x3, the site where the upper cladding 21 is removed, the light light-shielding layer 26 _{1-26 7} to shield
Is provided. These light-shielding layer 26 _{1-26 7,}
As shown in FIG. 11, it is formed over a range of a predetermined length 13 across the groove 3.

[0142] In the above configuration, focusing the signal light of the fourth channel transmitted from the optical waveguide 2 _4, the signal light transmitted through the optical waveguide 2 _4, the upstream end face 31
(See FIG. 2), a part of the signal light is equalized for each polarization state by the reflection filter 4 inclined with respect to the optical axis. The light is reflected obliquely upward from the optical planar waveguide circuit 1 at a predetermined reflectance whose polarization has been compensated for. The signal light components other than it is transmitted through the inner filling resin portion 51 and the reflective filter 4, it is incident again to the optical waveguide 2 ₄ via the downstream other surface 32.

[0143] On the other hand, the light reflected by the reflection filter 4, inside the filling resin 51, the optical waveguide 2 _4, and via the upper filling resin portion 52, is incident on the photodetector 67 _4. Then, the light intensity of the reflected light detected by the photodetector 67 _4, the light intensity of the signal light of the fourth channel being transmitted through the optical waveguide 2 ₄ is monitored.

[0144] Further, the optical waveguide 2 ₄ viewed from of the light-waveguide 2 ₃ and the light detector 67 ₃ side of the upper clad 21, the light shielding layer 26 ₃ is provided. The light-shielding layer 26 _3,
Of the signal light being transmitted through the optical waveguide 2 _4, scattering of light, reflection, light is propagated to the photodetector 67 ₃ adjacent the like spread of light to be transmitted is blocked, third, fourth The occurrence of crosstalk between channels is prevented.

[0145] Further, the optical waveguide 2 ₄ viewed from of the light-waveguide 2 ₅ and the photodetector 67 ₅ side of the upper clad 21, the light shielding layer 26 ₄ is provided. The light-shielding layer 26 _4,
Of the signal light being transmitted through the optical waveguide 2 _4, scattering of light, reflection, light is propagated to the photodetector 67 ₅ adjacent the like spread of light to be transmitted is blocked, fourth, fifth The occurrence of crosstalk between channels is prevented.

[0146] In the present embodiment, similarly to the light-shielding layer 25 _to 253 ₇ in the third embodiment shown in FIGS. 7 and 8, the reflected optical path from the reflection filter 4 to the photodetector 67 _{1-67 8} with respect to the optical planar waveguide circuit 1, the light-shielding layer 26 _{1-26 7} as an optical path isolation means for isolating the reflected light path between
Is provided. Thereby, as described above, it is possible to reliably prevent the occurrence of crosstalk between adjacent channels.

[0147] Further, an upper cladding 21 in this manner the optical waveguide 2 ₁ to 2 _8, by filling the resin between the photodetector array 66, according to the structure in which the upper filling resin portion 52, the upper Even when the surface of the clad 21 has irregularities, irregular reflection and scattering of light due to the irregularities are suppressed.

As an example, by providing a light shielding layer in the upper cladding of the optical planar waveguide type circuit as described above for the state where the crosstalk has been degraded to -20 dB.
Crosstalk was improved up to a level of <-28 dB.

The optical waveguide module according to the present invention is not limited to the above-described embodiments and examples, but can be variously modified. For example, the polarization compensation of the reflectance difference in the reflection filter 4 is to compensate for the reflectance difference in the reflection filter 4 itself, but the optical waveguide 2 _n , the filling resin 5, and the photodetector 6 _n If it is known in advance that the polarization dependence is caused by reflection at the interface, the reflection filter 4 may be configured with a reflectance that also compensates for them.

The optical path isolation means for preventing the occurrence of crosstalk between adjacent channels is described below.
Not limited to the above-described configuration, various configurations may be used. For example, when the light shielding member is provided in the filling resin, the light shielding member may be provided separately from the submount substrate, or the light shielding member may be provided in the internal filling resin portion. Alternatively, the light shielding member provided in the upper clad, the light shielding member provided in the filling resin, and the like may be used in combination to further improve the crosstalk.

[0151]

As described in detail above, the optical waveguide module according to the present invention has the following effects. That is, according to the optical waveguide module having a configuration in which a diagonal groove is formed so as to cross the optical waveguide and a part of the signal light is reflected by a reflection filter installed inside the groove to monitor the light intensity. Therefore, the configuration and manufacturing process of the optical circuit are simplified. In addition, by using a reflection filter that realizes polarization compensation for equalizing the reflectance between the orthogonal polarizations, it is possible to correctly monitor the light intensity regardless of the polarization state of the signal light. Further, since the inside of the groove including the reflection filter is sealed with the filling resin, deterioration of long-term operation stability due to contamination of the groove is prevented.

Such an optical waveguide module can be applied as a signal light intensity monitor to be inserted into an optical circuit including an optical fiber and an optical planar waveguide. Alternatively, it is also possible to adopt a configuration in which the signal light intensity is monitored in the optical circuit by providing it at a predetermined portion of an optical planar waveguide type circuit such as an optical multiplexer, an optical demultiplexer, or an optical attenuator.

The N reflected by the reflection filter
By providing optical path isolation means between adjacent reflected optical paths for N reflected optical paths through which signal light of a channel is propagated to the photodetector, occurrence of crosstalk between adjacent channels is minimized. be able to. This allows
With respect to the N-channel signal light transmitted through each optical waveguide, it is possible to accurately monitor the light intensity of the signal light in each channel.

[Brief description of the drawings]

FIG. 1 is a plan view showing a configuration of a first embodiment of an optical waveguide module.

FIG. 2 is a cross-sectional view showing a partially enlarged cross-sectional structure along an optical axis of the optical waveguide module shown in FIG.

FIG. 3 is a graph showing a change in polarization dependent loss when the inclination of a reflection surface with respect to an optical axis through which signal light is transmitted is changed.

FIG. 4 is a schematic diagram for explaining the shape of a light spot reflected by the light reflected by the reflection filter and the shape of the light receiving surface of the photodetector.

FIG. 5 is a plan view showing a configuration of a second embodiment of the optical waveguide module.

6 is a cross-sectional view showing a partially enlarged cross-sectional structure along the optical axis of the optical waveguide module shown in FIG.

FIG. 7 is a plan view showing a configuration of a third embodiment of the optical waveguide module.

8 is a cross-sectional view taken along the line II of FIG. 7, showing a partially enlarged cross-sectional structure perpendicular to the optical axis of the optical waveguide module shown in FIG. 7;

FIG. 9 is a plan view illustrating a configuration of a fourth embodiment of the optical waveguide module.

10 is a cross-sectional view taken along the line II-II of the optical waveguide module shown in FIG. 9, which is partially enlarged in cross section perpendicular to the optical axis.

FIG. 11 is a plan view showing a configuration of a fifth embodiment of the optical waveguide module.

12 is a cross-sectional view of the optical waveguide module shown in FIG. 11, taken along the line III-III, showing a partially enlarged cross-sectional structure perpendicular to the optical axis.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical planar waveguide type circuit, 10 ... Substrate, 11 ... Input end,
12 ... output terminal, 2 ₁ to 2 ₈ ... optical waveguide, 20: core, 21
... upper cladding, 22 ... lower cladding, 25 _{1 to} 25 ₇ ,
26 _{1 to} 26 ₇ ... light shielding layer, 3 ... groove, 31 ... upstream end face,
32: downstream end face, 4: reflection filter, 5: filling resin,
51 ... internal filling resin part, 52 ... upper filling resin part, 6, 6
0,62,64,66 ... photodetector array, ₆₁ through _8, 6
1 _{1-61 8,} 63 ₁ to 63 _8, 65 ₁ to 65 _8, 67 _1-6
7 ₈ ... photodetector, 7,70,72 ... submount substrate,
71 _{1 to} 71 ₇ … light shielding portion.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takeo Komiya 1st, Tayacho, Sakae-ku, Yokohama-shi, Kanagawa Prefecture Sumitomo Electric Industries, Ltd. Yokohama Works (72) Inventor Masahide Saito 1st, Tayacho, Sakae-ku, Yokohama-shi, Kanagawa Sumitomo F-term in Yokohama Electric Works (Reference) 2H047 KA04 KA15 KB09 LA09 LA14 LA18 MA07 TA22 5F088 AA01 BA03 BA18 BB01 JA03 JA06 JA13 JA14 JA20

Claims (10)

[Claims] 1. A vertical axis orthogonal to an optical axis of the optical waveguide so as to cross a predetermined portion of the optical waveguide, the substrate including a substrate and a planar waveguide type optical waveguide formed on the substrate. An optical planar waveguide circuit having a groove formed obliquely at a predetermined inclination angle θ (0 ° <θ); and transmitting the optical waveguide inside the groove of the optical planar waveguide circuit. A reflection filter is installed including a portion through which the signal light passes, and reflects a part of the signal light with a predetermined reflectance in which a difference in reflectance between the orthogonal polarizations is compensated. An optical waveguide module, comprising: a filling resin filled so as to seal the inside of the groove; and a photodetector that detects reflected light in which the signal light is reflected by the reflection filter. 2. The optical waveguide according to claim 1, wherein the inclination angle θ of the groove formed in the optical planar waveguide type circuit is within an angle range of 0 ° <θ ≦ 40 °. module. 3. The optical waveguide module according to claim 1, wherein a resin material having substantially the same refractive index as the core of the optical waveguide is used as the filling resin. 4. The filling resin is filled so as to seal a predetermined area on an upper surface of the optical planar waveguide type circuit including an upper side of the groove, in addition to an inner side of the groove, and fill the groove. 2. A resin material having substantially the same refractive index as the internal filling resin for sealing the inside and the upper filling resin for sealing the upper surface of the optical planar waveguide type circuit. Optical waveguide module. 5. A coating film for preventing reflection of an optical wavelength band to be used is provided at an interface between the optical planar waveguide circuit and the photodetector or an interface between the filling resin and the photodetector. The optical waveguide module according to claim 1, wherein 6. The light receiving surface of the photodetector is formed in a substantially elliptical shape including an elliptical reflected light spot due to the reflected light reflected by the reflection filter. Optical waveguide module. 7. The optical planar waveguide circuit includes N (N is a plurality) optical waveguides as the optical waveguides, and the photodetector includes N optical waveguides corresponding to the N optical waveguides, respectively.
And a part of the signal light transmitted through each of the N optical waveguides is reflected by the reflection filter to the corresponding one of the N light paths. 2. The optical waveguide module according to claim 1, wherein an optical path isolating means for isolating the reflected optical paths is provided between each of the N reflected optical paths. 8. The optical path isolating means is disposed between each of the N optical waveguides in the optical planar waveguide type circuit so as to block light passing from the reflected optical path to an adjacent reflected optical path. The optical waveguide module according to claim 7, wherein the optical waveguide module is provided. 9. The light path isolating means is a light shielding means provided in the filling resin so as to shield light passing from the reflected light path to an adjacent reflected light path. 8. The optical waveguide module according to 7. 10. The optical resin according to claim 1, wherein the filling resin is filled so as to seal a predetermined area of an upper surface of the optical planar waveguide circuit including an upper side of the groove, in addition to an inner side of the groove. A mounting member for mounting the N photodetectors is provided on an upper surface side of the waveguide type circuit, and the light shielding unit is configured to seal an upper surface of the optical planar waveguide type circuit. 10. A light shielding portion provided on the mounting member so as to protrude into the resin.
An optical waveguide module as described in the above.