JP2007011143A - Optical module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical module in which the positioning accuracy between a light transmitting member and an optical element is improved.
When assembling an optical module, an optical element is first arranged and fixed at a predetermined position in a housing. Next, the position of the holder 19 is adjusted, the light transmitting member 18 is positioned with respect to the optical element 2, and the holder 19 is fixed to the housing 4. Thus, since the holder 19 can be fixed to the housing 4 after the optical device 2 is mounted on a predetermined part in the housing 4, the light transmission member 18 can be easily positioned with respect to the optical device 2. It is possible to improve the positioning accuracy.
[Selection] Figure 1

Description

  The present invention relates to an optical module used in, for example, an optical communication system.

  In an optical communication system such as an optical LAN using light as an information transmission medium, information is transmitted by transmitting an optical signal via an optical fiber transmission line. In such an optical communication system, an optical communication module including an optical element that mutually converts an optical signal and an electrical signal is used to receive or transmit a transmitted optical signal.

Conventionally, as an optical module such as the above optical communication module, for example, a light emitting element that emits light and a casing (package) that accommodates the light emitting element are provided, and light from the light emitting element is supplied to the casing. A lens having a lens that allows the light to pass outside the housing is known (see, for example, Patent Document 1). In such an optical module, a lens is first attached to a housing, and the light emitting element is mounted on the lens by positioning the light emitting element.
JP 2001-156194 A

  However, in the prior art described in Patent Document 1, since the optical element is mounted on the mounting surface in the casing after the lens is attached to the casing, the relative positional relationship between the lens and the optical element is likely to vary. The positional accuracy of the optical element with respect to was insufficient. In particular, positioning in the direction (height direction) perpendicular to the mounting surface makes it difficult to absorb the dimensional tolerance in the height direction of components such as a housing, an optical element, and a base on which the optical element is mounted. As a result, when the optical fiber and the optical element are optically coupled, the positional relationship between the optical fiber and the optical element tends to vary.

  The present invention has been made to solve such a problem, and an object thereof is to provide an optical module in which the positioning accuracy between the light transmitting member and the optical element is improved.

  An optical module according to the present invention is an optical module including an optical element that emits or receives light, a package that houses the optical element, and a holder that is fixed to the package and mounts a light transmitting member therein. Has a rectangular bottom surface and four side wall surfaces surrounding the bottom surface, and one side wall surface is provided with an opening for transmitting light, and one side wall surface is connected to the opening. The optical element is housed in the package body, the holder engages the cylinder, the cylinder has a first flange at the tip, and the holder has a second flange. The first flange and the second flange are projection welded.

  According to such an optical module, it has the 1st flange provided in the front-end | tip of a cylinder part, and the 2nd flange provided in the holder, and a 1st flange and a 2nd flange are projection welding. Has been. Thereby, as before, the light transmission member does not have to be fixed to the package first. Therefore, after mounting the optical element in the package, the holder for mounting the light transmitting member can be fixed to the package. As a result, positioning of the light transmission member with respect to the optical element is facilitated, and positioning accuracy can be improved.

  Preferably, the first flange is formed at a position spaced from the package body. In this case, since the electrode for projection welding can be arrange | positioned between a housing | casing and a 1st flange, it becomes possible to receive the applied pressure applied in the case of projection welding with a 1st flange reliably. Thereby, the airtight defect between a 1st flange and a 2nd flange does not occur easily, but highly reliable welding is attained.

  Preferably, the light transmission member is a lens. In this case, it is not necessary to provide a hermetic sealing sapphire window or the like by closing the opening formed in the housing with a lens, so that the cost can be reduced.

  According to the optical module of the present invention, it is possible to provide an optical module with improved positioning accuracy while easily positioning the light transmitting member with respect to the optical element. For this reason, it becomes possible to improve a yield and to reduce the manufacturing cost of an optical module.

  Hereinafter, preferred embodiments of an optical module according to the present invention will be described with reference to the drawings. In the description of the drawings, the same or corresponding elements are denoted by the same reference numerals, and redundant description is omitted. FIG. 1 is a sectional perspective view in which a light emitting module according to an embodiment of the present invention is cut along an axis, and FIG. 2 is a sectional perspective view showing the inside of a package body in FIG.

  A light emitting module (optical module) 1 shown in FIG. 1 is applied to an optical transmission device, and includes a light emitting element (laser diode, hereinafter referred to as LD) 2 that emits light, and a package 3 that accommodates the LD 2. . In the following description, the traveling direction of the light emitted from the LD 2 is defined as “front”, and terms such as “front” and “rear” are used.

  The package 3 includes a package body 4 that forms a box shape and forms a space for accommodating the LD 2, and a lid 5 that seals the upper opening 4 a of the package body 4. The package body 4 includes a bottom wall portion 6 that forms a rectangular (rectangular) bottom surface, a front wall portion 7 that forms a wall surface rising from the front end of the bottom wall portion 6, and the bottom wall portion 6 and the front wall portion. 7, a pair of side wall portions 8 constituting a wall surface substantially orthogonal to 7 and a rear wall portion 9 substantially orthogonal to the side wall portion 8 and constituting a rear wall surface are formed from a metal material.

  As shown in FIGS. 1 and 2, in addition to the LD 2, a Peltier element 10 for cooling the LD 2 and a plurality of wiring patterns (not shown) are formed in the package body 4 in a stacked state. A laminated ceramic wiring board 11 is provided. The Peltier element 10 and the multilayer ceramic wiring substrate 11 are disposed adjacent to each other in the front-rear direction and are fixed to the upper surface of the bottom wall portion 6.

  The Peltier element 10 forms a block body, and the LD 2 is fixed to the upper surface of the Peltier element 10 via a plate-shaped heat sink 12. In this example, an LD driving circuit 13 and a thermistor 14 for driving the LD 2 are also provided on the heat sink 12. The heat sink 12 is formed of, for example, AlN, which is an insulating material having good thermal conductivity, and transfers heat from the LD 2 and the LD drive circuit 13 to the Peltier element 10, so that the LD 2 and LD drive circuit 13 are connected. Cool efficiently.

  On the upper surface of the multilayer ceramic wiring board 11, a monitor light receiving element (for example, a photodiode: PD) 15 for receiving the backward light of the LD 2 is mounted. The LD drive circuit 13 and the multilayer ceramic wiring substrate 11 are electrically connected by wire leads (not shown). Further, the rear end portion 11 b of the multilayer ceramic wiring board 11 extends to the outside of the package body 4. A lead 16 is electrically connected to the rear end portion 11b.

  As shown in FIGS. 1 and 2, the front wall 7 of the package body 4 is provided with an opening 7 a through which light from the LD 2 passes. The front wall portion 7 has a cylindrical portion 17 toward the front, and an inner hole of the cylindrical portion 17 opens (opens) toward the package body 4. The distal end portion of the cylindrical portion 17 has a flange (first flange) 17a, and the distal end surface of the flange 17a serves as a surface for fixing the lens holder 19 as will be described later.

  As shown in FIGS. 1 and 3, a lens 18 that collects light from the LD 2 is disposed in the cylindrical portion 17. Although this lens 18 uses a spherical lens in this example, it is held by a lens holder 19 and inserted into the cylindrical portion 17. The lens holder 19 has cylindrical bodies having different outer diameters and inner diameters in the direction of the axis L. Specifically, the lens holder 19 includes a first cylindrical portion 19a extending in the direction of the package body 4 with a flange (second flange) 19b interposed therebetween, and a side opposite to the first cylindrical portion 19a from the flange 19b. And a second cylindrical portion 19c that extends. The first cylindrical portion 19 a functions as a lens holding portion that holds the lens 18.

  The outer diameter of the lens holding portion 19 a is set smaller than the inner diameter of the cylindrical portion 17. The lens 18 is fixed to the rear end side in the lens holding portion 19a. The flange 19b has a fixed surface 19d facing the flange 17a. The fixed surface 19d is formed with a projection 19e projecting toward the flange 17a in an annular shape, and this projection 19e is used for projection welding for joining the flange 17a and the flange 19b.

  As shown in FIG. 1, the second cylindrical portion 19c has an alignment member 20 mounted on the outer periphery thereof. The alignment member 20 is slidable in the Z (optical axis) direction on the outer periphery of the second cylindrical portion 19c. A sleeve assembly 22 that holds the optical fiber ferrule is attached to the front end side of the alignment member 20. The front end surface 20a of the alignment member 20 is a sliding surface on which the sleeve assembly 22 can slide in the XY (perpendicular to the optical axis) direction. The sleeve assembly 22 includes a bush 22a, a sleeve 22b, a sleeve cover 22c, a stub 22d, and a coupling fiber 22e inserted in the center of the stub 22d. The bush 22a holds the base of the sleeve 22b between the stub 22d. In other words, the bush 22a is inserted between the stub 22d and the sleeve cover 22c at the root of the sleeve 22b. The light emitted from the LD 2 is collected by the lens 18 at the end of the coupling fiber 22e. The optical fiber coupled to the light emitting module 1 has a ferrule at its tip, and the ferrule abuts against a stub 22d inserted from the front end of the sleeve 22b. An optical fiber is also inserted into the center of the ferrule, and the optical fiber and the coupling fiber 22e at the center of the stub come into physical contact (Physical Contact) when the end face of the stub 22d and the end face of the ferrule abut against each other. As a result, it is transmitted to the optical fiber emitted from the LD 2 and propagates through the fiber.

  Next, assembly of the light emitting module 1 will be described. First, as shown in FIG. 2, the LD 2, the thermistor 14, the heat sink 12, the Peltier element 10, the photodiode 15, and the multilayer ceramic wiring board 11 are arranged and fixed at predetermined positions in the package body 4, and are attached to necessary places. Wire bonding is performed. Subsequently, as shown in FIGS. 3 and 4, the lens holder 19 to which the lens 18 is fixed is inserted into the cylindrical portion 17 from the lens 18 side.

  Next, the flange 17 a of the package 3 and the flange 19 b of the lens holder 19 are joined by projection welding to fix the lens holder 19 to the package 3.

  In this step, first, as shown in FIGS. 6 and 7, the package body 4 and the lens holder 19 are set in a resistance welding machine 24 for projection welding. The resistance welder 24 includes a package side electrode 25 for energizing the flange 17a and a lens holder side electrode 26 for energizing the flange 19b.

  The package side electrode 25 has a substantially cylindrical shape and includes a package housing portion 27 for housing the package body 4 and a pair of electrode portions 28 for holding the flange 17a and energizing the flange 17a. The package housing portion 27 is arranged so that the longitudinal direction of the hollow portion extends in the vertical direction. A stepped surface 27 a for supporting the electrode portion 28 is formed at the peripheral edge portion that forms the opening of the package housing portion 27.

  The electrode portion 28 has a semicircular shape, and an arc portion thereof is supported by the step surface 27 a of the package housing portion 27. The pair of electrode portions 28 are arranged so as to sandwich the cylindrical portion 17 of the package 3 from both sides. A stepped surface 28 a for supporting the flange 17 a of the cylindrical portion 17 is formed on the upper end surface side of the electrode portion 28. And the electrode part 28 approached between the flange 17a and the front wall part 7, and has supported the flange 17a by the level | step difference surface 28a. That is, the package body 4 is configured such that the electrode portion 28 can enter the gap by providing a gap between the front wall portion 7 and the flange 17a.

  The lens holder-side electrode 26 has a substantially cylindrical shape, and has a conical portion 26a whose outer diameter decreases toward the tip. A through hole 26b having a circular cross section is formed at the axis of the lens holder side electrode 26. The diameter of the through hole 26b is set such that the second cylindrical portion 19c of the lens holder 19 can be inserted. Further, the tip of the conical part 26 a forms a pressing surface 26 c that presses the flange 19 b of the lens holder 19.

  Then, the package 3 is mounted on the package-side electrode 25 and the position of the LD 2 and the lens 18 is adjusted in a plane perpendicular to the axis L with the lens holder 19 inserted into the cylindrical portion 17. Since the outer diameter of the lens holding portion 19a of the lens holder 19 is set slightly smaller than the inner diameter of the cylindrical portion 17, the optical axis can be adjusted within the range of the gap between the two. The position adjustment between the LD 2 and the lens 18 is performed as follows, for example. That is, first, the LD 2 is caused to emit light. Next, using a position adjusting camera (not shown) arranged at a position facing the LD 2 outside the package 3, the center of the lens 18 is detected and the light emitting point of the LD 2 is observed, and the lens holder 19 is moved. The position of the LD 2 and the lens 18 is adjusted.

  After positioning the lens 18, projection welding is executed by applying current to the package side electrode 25 and the lens holder side electrode 26 while pressing the flange 19 b downward by the lens holder side electrode 26. At this time, as shown in FIG. 7, the current flows through the lens holder side electrode 26, the flange 19b, the flange 17a, and the package side electrode 25, the protrusion 19e is melted, and the flange 19b is fixed to the flange 17a. Is done. The current flows only between the two electrodes of the resistance welder, the lens holder side electrode 26 and the package side electrode 25, and no current flows through the package body 4 and the multilayer ceramic wiring substrate 11. The joint portion between the wiring board 11 and the package body 4 is not destroyed. The airtightness of the package 3 can be reliably maintained by projection welding. In such projection welding, although it depends on the shape, area, etc. of the projection, it can be satisfactorily fixed by applying pressure while flowing a current of 2.3 kA to 10 kA.

  Subsequently, the package body 4 is removed from the resistance welder 24, and as shown in FIG. 5, the alignment member 20 is connected to the lens holder 19, and the sleeve assembly 22 separately assembled inside is further connected to the alignment member 20. Install. The alignment member 20 is slid on the outer peripheral surface of the lens holder 19 to adjust the position in the Z direction, and the sleeve assembly 22 is slid relative to the alignment member 20 to adjust the position in the XY direction. The optical coupling state with the fiber 21a is optimized. In this state, the lens holder 19 and the alignment member 20, and the alignment member 20 and the sleeve assembly 22 are joined. These joints are preferably performed by YAG welding. In this way, the light emitting module 1 can be obtained. The lid 5 may be mounted after the projection welding or immediately after the LD 2 or the like is mounted in the package body 4.

  According to such a light emitting module 1, since the lens 18 can be fixed to the package body 4 after the LD 2 is mounted at a predetermined position in the package body 4, the positioning of the LD 2 and the lens 18 is achieved. It is possible to improve the positioning accuracy of both while performing the above. As an example, in the conventional light emitting module 51 shown in FIG. 8, since the LD 52 and the lens 53 are arranged on the same plane, alignment in the Y direction (height direction) is difficult. On the other hand, since the light emitting module 1 of the present embodiment has a configuration capable of absorbing a dimensional error in the Y direction, it is possible to align the LD 2 and the lens 18 with high accuracy.

  Further, since the positioning of the LD 2 and the lens 18 can be performed with high accuracy, it is not necessary to increase the area of the lens 18 in order to secure a position adjustment margin. Thereby, the lens 18 can be downsized.

  Further, the light emitting module 51 shown in FIG. 8 has a structure in which the opening 55 a of the package body 55 is sealed using a sapphire window 54. In the light emitting module 1 according to the present embodiment, since the opening 7a of the package body 4 is hermetically sealed by the lens 18 and the lens holder 19, there is no need to provide a sapphire window 54 as in the related art. The number of points can be reduced.

  As mentioned above, although this invention was concretely demonstrated based on the embodiment, this invention is not limited to the said embodiment. In the said embodiment, although it is set as the light emitting module 1 provided with LD2, it is good also as a light receiving module provided with PD.

  In the above embodiment, the lens is arranged in the cylindrical portion 17, but the light transmitting member may be arranged in the package body 4.

It is the cross-sectional perspective view which fractured | ruptured the light emitting module which concerns on embodiment of this invention along an axis line. It is a cross-sectional perspective view which shows the inside of the package main body in FIG. It is a cross-sectional perspective view which shows the manufacturing process of the light emitting module of FIG. It is another cross-sectional perspective view which shows the manufacturing process of the light emitting module of FIG. It is a cross-sectional perspective view which shows the light emitting module of FIG. It is a perspective view which shows the welding process of the package of FIG. 2, and a lens holder. It is a cross-sectional perspective view which shows the welding process of FIG. It is a cross-sectional perspective view which shows the conventional light emitting module.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Light emitting module (optical module), 2 ... Light emitting element (optical element), 4 ... Package main body (housing), 7 ... Front wall part (one side wall surface), 7a ... Opening part (opening), 17 ... Cylindrical portion, 17a ... flange (first flange), 18 ... lens (light transmitting member), 19 ... lens holder (holder), 19b ... flange (second flange), 19e ... projection, 20 ... alignment member , 22 ... Sleeve assembly.

Claims (3)

An optical element that emits or receives light; and
A package containing the optical element;
An optical module comprising a holder fixed to the package and mounting a light transmissive member therein,
The package has a rectangular bottom surface and four side wall surfaces surrounding the bottom surface, and one side wall surface is provided with an opening through which light is transmitted, and the package body is connected to the opening. A cylindrical portion extending from one side wall surface,
The optical element is accommodated in the package body,
The holder engages with the cylindrical portion,
The cylindrical portion has a first flange at the tip, the holder has a second flange, and the first flange and the second flange are projection welded.
An optical module characterized by that.   The optical module according to claim 1, wherein the first flange is formed at a position separated from the package body.   The optical module according to claim 2, wherein the light transmitting member is a lens.

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