JP2003294529A - Light intensity measuring device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure light intensity highly accurately by a light intensity measuring device. <P>SOLUTION: This light intensity measuring device includes an array waveguide lattice 302 for separating input light into one or more light signals and outputting output light of the separated light signals, and photodetectors 304-1 to 304-n for measuring the intensity of the output light. In the device, a waveguide transmission property which is a relation between the wavelength of the separated light signal and the transmission intensity of the output light is changed by a temperature control device 306 in the array waveguide lattice 302, and a data processing device 307 accumulates measurement data measured by the photodetectors 304-1 to 304-n and determines the intensity of the separated light signals based on the maximum value of the measurement data. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light intensity measuring device and method, and more particularly, to a light intensity measuring device and method capable of highly accurately measuring the optical signal intensity of each wavelength in optical wavelength division multiplexing communication. Regarding

[0002]

2. Description of the Related Art In conventional optical communication using an optical fiber as a transmission path, a transmission loss of an optical signal to be transmitted does not depend on a modulation rate, so that a large amount of information up to the performance limit of a transmitter / receiver can be transmitted. Is. Furthermore, in wavelength division multiplexing optical communication, in which optical signals of different wavelengths are multiplexed and transmitted in an optical fiber, it is possible to transmit information with a capacity that is several times the wavelength to be multiplexed, compared to the transmission capacity of conventional optical communication. Is.

Generally, in optical communication, in order to compensate for transmission loss of an optical fiber, a relay station measures the intensity of an optical signal transmitted, and compensates by adding desired attenuation according to the measured intensity. I do. In the conventional wavelength division multiplexing optical communication, a part of the transmitted light is branched at the relay station, and the branched light is guided to the optical intensity measurement system (for example, Japanese Patent Laid-Open No. 2001-168841).

As shown in FIG. 1, such a measuring system is
After separating an optical signal using an optical wavelength demultiplexer, the intensity of the optical signal is measured for each wavelength. In the figure, reference numeral 101 is an input optical fiber that guides the branched wavelength division multiplexed light, reference numeral 102 is an optical wavelength demultiplexer, and reference numerals 103-1 to 10-n.
Is an output optical fiber, reference numerals 104-1 to n are light receivers, and reference numeral 107 is a data processing device. In this optical intensity measuring device, the wavelength-multiplexed optical signal input to the optical wavelength demultiplexing device 102 through the input optical fiber 101 is wavelength-demultiplexed by the optical wavelength demultiplexing device 102, and then the output optical fiber 103-1.
The light intensity is measured by the light receivers 104-1 to 104-n via the data processing device 1 through n, and the data processing device 107 calculates and stores the light intensity.
These measurement results are used when performing a desired amount of compensation such as setting of the attenuation value.

An arrayed waveguide grating is used as a general optical wavelength demultiplexer. The arrayed-waveguide grating separates the wavelength-multiplexed signal for each wavelength as follows. Figure 2
(A), (b) is a figure showing the wavelength transmission characteristic using the conventional arrayed-waveguide grating. FIG. 2A is a diagram showing wavelength transmission characteristics in a conventional light intensity measuring device using an arrayed waveguide grating. FIG. 2B is a diagram showing a wavelength shift between the maximum transmission wavelength and the wavelength of the optical signal in the conventional light intensity measuring device using the arrayed waveguide grating.

That is, the arrayed waveguide grating has a wavelength transmission characteristic as shown in FIG. 2A for an optical signal input from the input port of the arrayed waveguide grating and output to each output port. Here, if the maximum transmission wavelength (peak wavelength of transmission intensity) corresponding to each output port matches each wavelength of the multiplexed optical signal, the light of the wavelength matching the maximum transmission wavelength is output to each output port. Only the signal will be retrieved. As a result, the optical signals separated for each wavelength are collectively output to each output port, which enables efficient optical intensity measurement.

[0007]

However, when measuring the intensity of the optical signal from the output port of the arrayed waveguide grating, the wavelength of the optical signal transmitted from the transmitting station is usually the maximum of the arrayed waveguide grating. It does not exactly match the transmission wavelength. For example, if there is a wavelength shift between the two as shown in FIG. 2B, the wavelength shift causes an error in the optical signal intensity observed at the output port. For example, when the wavelength shift between the two is 0.1 nm as shown in FIG. 2B, the light intensity measured by this shift is displayed about 0.8 dB smaller than the actual optical signal intensity. Will be.

That is, in the above-mentioned light intensity measuring device, since it is possible to transmit the light through the arrayed-waveguide grating and to output it collectively, it is possible to measure the light intensity efficiently. The prior art has a problem to be solved that a deviation from the maximum transmission wavelength of the arrayed waveguide grating causes an error in the measurement of the optical signal intensity.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a light intensity measuring apparatus and method capable of highly accurately measuring the light intensity.

[0010]

In order to achieve such an object, the optical intensity measuring apparatus of the present invention splits the input light into one or more optical signals and outputs the output light of the separated optical signals. An optical intensity measuring device including an optical wavelength demultiplexing means and a measuring means for measuring the intensity of output light from the optical wavelength demultiplexing means, wherein the wavelength and the intensity of the optical signal in the optical wavelength demultiplexing means And a data processing means for accumulating measurement data of the intensity measured by the measuring means and determining the intensity of the optical signal based on a predetermined value of the accumulated measurement data. It is characterized by that.

The predetermined value may be a maximum value.

Further, the data processing means may be characterized in that the intensity of the optical signal is obtained based on the maximum value and a minimum transmission loss of the optical wavelength demultiplexing means measured in advance.

Further, the optical wavelength separation means is an arrayed waveguide grating, and the control means changes the temperature of the arrayed waveguide grating to change the relationship between the wavelength and the intensity of the output light. It can be a feature.

In order to achieve the above-mentioned object, the light intensity measuring method of the present invention comprises an optical wavelength separating means for separating the input light into one or more optical signals and outputting the output light of the separated optical signals. A light intensity measuring method of a light intensity measuring device including a measuring unit for measuring the intensity of output light from the light wavelength separating unit, wherein the relationship between the wavelength and the intensity of the optical signal in the light wavelength separating unit And a separation step of separating the input light and outputting the output light by the optical wavelength separation means in which the relationship between the wavelength and the intensity is changed by the control step, and output by the separation step. Measuring step of measuring the intensity of the output light thus obtained by the measuring means, accumulating measurement data of the measured intensity measured by the measuring step, and accumulating the accumulated measurement data. Characterized by comprising a data processing step of obtaining the intensity of the optical signal based on a predetermined value.

In the above configuration of the present invention, the maximum transmission wavelength (peak wavelength of transmission intensity) of the light wavelength separation means is changed during a fixed time, and the light intensity is repeatedly measured at high speed during the fixed time. The most important feature is that the maximum value of these measured values is the optical signal intensity. This is different from the conventional technique in that the optical signal intensity is not measured with the maximum transmission wavelength of the optical wavelength separation means fixed.

With the above configuration of the present invention, by changing the maximum transmission wavelength of the light wavelength separation means within a fixed time,
A state in which the maximum transmission wavelength of the optical wavelength separation means and the optical signal wavelength coincide with each other is realized within this fixed time.

If a state where the maximum transmission wavelength of the optical wavelength demultiplexing means and the optical signal wavelength match can be realized, the loss of the optical wavelength demultiplexing means in this state can be specified by a known value as the minimum transmission loss. That is, in the present invention, it is important to change the wavelength transmission characteristics so that the maximum point of light intensity appears. If you change the optical intensity so that the maximum point does not appear, the wavelength of the optical signal is unknown.
It is not possible to specify at which point on the wavelength transmission characteristics of the optical wavelength demultiplexing means the optical signal has been lost, and the desired light intensity cannot be obtained.

Further, since the light intensity is repeatedly measured at a high speed during this fixed time and the maximum value of these measured values is taken as the optical signal intensity, the maximum transmission wavelength and the optical signal wavelength of the optical wavelength separating means are Since the optical signal intensity in the matched state can be measured, the error in the optical signal intensity measurement value due to the wavelength shift between the two can be eliminated, and the highly accurate optical signal intensity measurement which is the object of the present invention can be realized. become able to.

[0019]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. In the drawings, parts having the same function are denoted by the same reference numerals, and duplicate description will be omitted.

[Embodiment 1] FIG. 3 is a block diagram of a light intensity measuring apparatus of the present embodiment 1, wherein reference numeral 301 is an input optical fiber, reference numeral 302 is an arrayed waveguide grating, reference numeral 303-1.
To n are output optical fibers, reference numerals 304-1 to n are photodetectors,
Reference numeral 305 is a temperature monitor, reference numeral 306 is a temperature control device,
Reference numeral 307 is a data processing device.

FIGS. 4 (a) and 4 (b) are diagrams of wavelength transmission characteristics of the light intensity measuring apparatus of the first embodiment. Figure 4 (a)
FIG. 6 is a diagram showing a change in wavelength transmission characteristics due to a change in temperature of the light intensity measuring device. FIG. 4B is a diagram showing a state where the maximum transmission wavelength of the light intensity measuring device and the wavelength of the optical signal match. Here, in FIG. 4A, the arrayed waveguide grating 3
The wavelength transmission characteristics of No. 02 at 40 ° C. and 60 ° C. are indicated by a broken line and a chain line, respectively, and the transmission characteristics of each wavelength at a temperature between 40 ° C. and 60 ° C. are indicated by a solid line.

In this optical intensity measuring apparatus, the wavelength-multiplexed optical signal input to the arrayed-waveguide grating 302 through the input optical fiber 301 is wavelength-separated by the arrayed-waveguide grating 302, and then output optical fiber 303-1. The light intensity is measured by the light receivers 304-1 to 30-n via the optical path units 1 to n. Here, while monitoring the temperature of the arrayed waveguide grating 302 with the temperature monitor 305, the temperature controller 306 repeatedly raises and lowers the temperature of the arrayed waveguide grating 302 between 40 ° C. and 60 ° C. in a cycle of about 1 second. .

Now, when the wavelength division multiplexed signal has a wavelength and intensity as shown by the solid line in FIG. 4B, for example, 5
When transmitted through the arrayed-waveguide grating 302 set at 0 ° C., the minimum transmission loss of the arrayed-waveguide grating 302 is caused in the optical signal of each wavelength due to the difference between the optical signal wavelength and the maximum transmission wavelength of the arrayed-waveguide grating 302. In addition to the above, a loss due to the wavelength shift is added, and the light is measured by the photo detectors 304-1 to 30-n.

Here, the temperature of the arrayed waveguide grating 302 is set to 4
The data processing device 307 measures the light intensity with the light receivers 304-1 to 30-n while repeatedly raising and lowering the temperature between 0 ° C. and 60 ° C.
When the data is accumulated at, the measured value of the photodetectors 304-1 to 30-n becomes the maximum, that is, the minimum transmission loss, at 53 ° C. where the maximum transmission wavelength of the arrayed waveguide grating 302 and the wavelength of the optical signal match.

By preliminarily measuring the loss at the maximum transmission wavelength, that is, the minimum transmission loss, the intensity of the optical signal can be obtained with high accuracy from the maximum value of the accumulated data in the data processing device 307. The cycle of temperature rise and fall of the arrayed waveguide grating 302 is set to 1 second, and the light receiver 304
By setting the measurement frequency at -1 to n to 1000 times per second, the optical signal intensity can be measured as the maximum value of the data processing device 307 with high accuracy within ± 0.1 dB regardless of the wavelength shift of the optical signal. It became possible.

In the first embodiment, an example in which an arrayed waveguide grating is used as the optical wavelength demultiplexing device is shown, but the same effect can be expected by using a dielectric multilayer film filter, a prism or the like.

[Second Embodiment] FIG. 5 is a block diagram of a light intensity measuring apparatus according to the second embodiment. In the figure, reference numeral 401 is an input optical fiber, reference numeral 402 is an optical demultiplexer, and reference numerals 403-1 to 403-n are shown. Output optical fiber, reference numerals 404-1 to 40-n are light receivers, reference numeral 40
5 is a current monitor, reference numeral 406 is a current control device, reference numeral 40
7 is a data processing device.

FIGS. 6A and 6B are diagrams showing the wavelength transmission characteristics of the light intensity measuring apparatus according to the second embodiment. Figure 6 (a)
FIG. 6 is a diagram showing a change in wavelength transmission characteristics due to a change in temperature of the light intensity measuring device. FIG. 6B is a diagram showing a state where the maximum transmission wavelength of the light intensity measuring device and the wavelength of the optical signal match. Here, in FIG. 6A, 1 of the optical demultiplexer 402 is used.
The wavelength transmission characteristics at 00 mA and 300 mA are shown by a broken line and a dashed line, respectively, and the transmission characteristics at each wavelength at a temperature between 100 mA and 300 mA are shown by a solid line.

In this optical intensity measuring apparatus, the wavelength division multiplexed optical signal input to the optical demultiplexer 402 through the input optical fiber 401 is wavelength-demultiplexed by the optical demultiplexer 402, and then the output optical fiber 403-1. -N through the light receiver 404-
The light intensity is measured from 1 to n. Here, while the temperature of the optical demultiplexer 402 is monitored by the current monitor 405, the current control device 406 repeatedly increases and decreases the current of the optical demultiplexer 402 between 100 mA and 300 mA in a cycle of about 0.1 seconds.

Now, when the wavelength division multiplexed signal has the wavelength and the intensity as shown by the solid line in FIG. 6B, for example, 2
When transmitted through the optical demultiplexer 402 set to 00 mA, due to the difference between the optical signal wavelength and the maximum transmission wavelength of the optical demultiplexer 402, the optical signal of each wavelength has a minimum transmission loss of the optical demultiplexer 402. In addition, the loss due to the wavelength shift is added, and
04-1 to n are measured. Here, the light intensity is measured by the light receivers 404-1 to 40-n while the current of the optical demultiplexer 402 is repeatedly increased and decreased between 100 mA and 300 mA, and the data is accumulated by the data processing device 407.
When the maximum transmission wavelength of 1 is 240 mA and the wavelength of the optical signal is 240 mA, the measured values of the light receivers 404-1 to 40-n are maximum, that is, the minimum transmission loss. By measuring the loss at the maximum transmission wavelength, that is, the minimum transmission loss in advance,
The intensity of the optical signal can be obtained with high accuracy from the maximum value of the accumulated data in the data processing device 407. Actually, the cycle of increasing / decreasing the current of the optical demultiplexer 402 is set to 0.1 seconds, and the optical receiver 4
The optical signal intensity is measured as the maximum value of the data processing device 407 with high accuracy within ± 0.1 dB regardless of the wavelength shift of the optical signal by setting the measurement frequency at 04-1 to n to 1000 times per second. Became possible.

In the second embodiment, an example in which the current is changed in order to change the maximum transmission wavelength of the optical wavelength demultiplexer is shown, but the maximum transmission wavelength may be changed by changing the applied voltage value or the like. It is possible. When the maximum transmission wavelength is changed by these current value and voltage value, the maximum transmission wavelength can be changed faster than the change in temperature by the temperature shown in the first embodiment. Thus, it becomes possible to measure data in a cycle of 0.1 second or less.

In the second embodiment, a dielectric multilayer filter, a prism or the like can be used as the optical wavelength demultiplexing device.

Although the above embodiment has been described for the purpose of exemplifying the present invention, modifications other than the above embodiment are possible.
As long as the modification is based on the technical idea of the present invention described in claims, the modification is within the technical scope of the present invention.

As described above, according to the present embodiment, the optical signal intensity can be measured in the state where the maximum transmission wavelength of the optical wavelength demultiplexing device and the optical signal wavelength match each other. There is an advantage that the error of the signal strength measurement value can be eliminated and an extremely highly accurate optical signal strength measurement can be realized.

[0035]

As described above, according to the present invention, the optical wavelength demultiplexing means for demultiplexing the input light into one or more optical signals and outputting their output light, and the measurement for measuring the intensity of the output light. An optical intensity measuring device including means changes the relationship between the wavelength of the optical signal in the optical wavelength separating means and the intensity, and outputs the output light by the optical wavelength separating means in which the relationship between the wavelength and the intensity changes. Then, the intensity of the output light output is measured by the measuring means, the measurement data is accumulated, and the intensity of the optical signal is obtained based on the predetermined value of the accumulated measurement data. The intensity of the optical signal is identified by identifying a predetermined value of the light intensity.

Therefore, the error of the optical signal intensity measurement value can be eliminated by specifying the predetermined value of the output light intensity of the optical wavelength demultiplexing means, and the highly accurate optical signal intensity measurement can be realized. Play.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a conventional light intensity measuring device.

2A and 2B are diagrams showing a wavelength transmission characteristic using a conventional arrayed waveguide grating, FIG. 2A is a diagram showing a wavelength transmission characteristic in an optical intensity measuring device using the arrayed waveguide grating, and FIG. It is a figure showing the wavelength gap of the maximum transmission wavelength and the wavelength of an optical signal in a light intensity measuring device using a waveguide grating.

FIG. 3 is a configuration diagram of a light intensity measuring device according to the first embodiment of the present invention.

4A and 4B are diagrams of wavelength transmission characteristics of the light intensity measuring apparatus according to the first embodiment, in which FIG. 4A shows a change in wavelength transmission characteristics due to temperature change of the light intensity measuring apparatus, and FIG. 4B shows light intensity measurement. It is a figure showing the state where the maximum transmission wavelength of an apparatus and the wavelength of an optical signal corresponded.

FIG. 5 is a configuration diagram of a light intensity measuring device according to a second embodiment of the present invention.

6A and 6B are diagrams of wavelength transmission characteristics of the light intensity measuring apparatus according to the second embodiment, in which FIG. 6A shows a change in wavelength transmission characteristics due to a temperature change of the light intensity measuring apparatus, and FIG. 6B shows light intensity measurement. It is a figure which shows the state where the maximum transmission wavelength of an apparatus and the wavelength of an optical signal corresponded.

[Explanation of symbols]

101 Input optical fiber 102 Optical wavelength demultiplexer 103-1 to n-output optical fiber 104-1 to n receiver 107 data processing device 301 Input optical fiber 302 arrayed waveguide grating 303-1 to n-output optical fiber 304-1 to n receiver 305 Temperature monitor 306 Temperature controller 307 Data processing device 401 Input optical fiber 402 Optical wavelength demultiplexer 403-1 to n output optical fiber 404-1 to n receiver 405 Current monitor 406 Current control device 407 Data processing device

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04B 10/14 H04B 9/00 S 10/16 10/17 H04J 14/00 14/02 (72) Inventor Shigeru Ono 1-12-1, Dogenzaka, Shibuya-ku, Tokyo F-Term (reference) in NTT Electronics Corporation 2G020 BA20 CC12 CC13 CC26 CD06 CD13 CD22 CD41 2G065 AA04 AB23 BA01 BB02 BB27 BB28 BB29 BC08 BC33 BC35 CA21 DA05 DA13 5K102 AA53 AD01 LA07 LA52 MA03 MB10 MC04 MC17 MD01 MD06 MH04 MH12 MH22 MH28 PC02 PH45 PH47 RB03 RD28

Claims (5)

[Claims] 1. An optical wavelength separation means for separating input light into one or more optical signals and outputting output light of the separated optical signals,
In a light intensity measuring device including a measuring unit that measures the intensity of the output light from the optical wavelength separating unit, a control unit that changes the relationship between the wavelength and the intensity of the optical signal in the optical wavelength separating unit, Light intensity measurement, comprising: data processing means for accumulating measurement data of the intensity measured by a measuring means, and obtaining intensity of the optical signal based on a predetermined value of the accumulated measurement data. apparatus. 2. The light intensity measuring device according to claim 1, wherein the predetermined value is a maximum value. 3. The optical intensity measuring device according to claim 2, wherein the data processing unit is configured to intensity the optical signal based on the maximum value and a minimum transmission loss of the optical wavelength demultiplexing unit measured in advance. A light intensity measuring device characterized in that 4. The light intensity measuring device according to claim 1, wherein the optical wavelength separation means is an arrayed waveguide grating, and the control means changes the temperature of the arrayed waveguide grating. The light intensity measuring device is characterized by changing the relationship between the wavelength and the intensity of the output light. 5. An optical wavelength demultiplexing means for demultiplexing the input light into one or more optical signals and outputting the output light of the demultiplexed optical signals,
In a light intensity measuring method of a light intensity measuring device including a measuring means for measuring the intensity of output light from the light wavelength separating means, the relationship between the wavelength and the intensity of the optical signal in the light wavelength separating means is changed. A control step, a separation step of separating the input light and outputting the output light by the optical wavelength separation means in which the relationship between the wavelength and the intensity changes by the control step, and an output output by the separation step A measuring step of measuring the intensity of light by the measuring means; accumulating measurement data of the intensity measured in the measuring step, and the optical signal based on a predetermined value of the accumulated measurement data. And a data processing step of obtaining the intensity of the light intensity.