JP2008026462A - Optical module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical module mounted with a correctly aligned lens. <P>SOLUTION: The optical module is mounted with on a carrier 13, a semiconductor laser, a lens 12 for collimating the light emitted by the semiconductor laser, and a lens holder 120 for holding the lens. Furthermore, the module has a frame 14 on the carrier 13, and an adhesive B for fixing the lens holder 120 is regulated by the frame 14. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical module in which a semiconductor laser, a lens for collimating light emitted from the semiconductor laser, and a lens holder for holding the lens are mounted on a carrier.

  In recent years, in the field of optical communication, it has been desired to realize a small-sized optical transceiver called XFP (10 Gigabit Small Form Factor Pluggable) for 10 Gbps communication that can support high-speed optical communication. The XFP optical transceiver accommodates an optical transmission / reception device, but the optical transmission / reception device requires a receptacle (adapter) for attaching / detaching a two-core LC connector. The receptacle (adapter) has a very narrow interval between transmission and reception, and the package of the XFP optical transceiver is standardized to a predetermined width and height. For this reason, the optical transmission / reception device mounted on the XFP needs to be downsized so as to be housed in the package.

  In the field of laser modules for optical communication, for example, a 14-pin butterfly type package is known as a standard as the above-described optical transmission device. As shown in FIG. 8, the butterfly package has a structure for extracting light from the glass sealing window 201. However, since the butterfly package does not have a vertically symmetric structure with respect to the optical axis, There is a possibility that the optical axis may be deviated from an optical system or fiber optical axis provided outside (not shown). Therefore, a lens (collimating lens) 203 as shown in the figure adjacent to the semiconductor laser 202 is inserted in the optical path inside the housing 200A, and once emitted as collimated light (parallel light) to the outside of the package 200A. Many have an optical system that focuses light on an external optical fiber (not shown). With such a configuration, even if there is a deviation in the optical axis between the internal optical system and the external optical system, it is possible to suppress degradation in optical coupling efficiency. In order to mount the lens 203 inside the housing 200 </ b> A, there is one that uses a carrier 204, and the lens 203 is mounted on the surface 204 </ b> A of the carrier 204.

  As a lens mounting method, there is a so-called “passive alignment” method in which a mounting guide such as a V-groove is formed with high accuracy in front of a light emitting element and a lens is mounted in accordance with the guide (for example, Patent Document 1). reference). This mounting method includes, for example, a V-groove formed with high accuracy using an anisotropic etching technique such as a silicon substrate, and an electrode or positioning for mounting an optical semiconductor element formed with higher accuracy with respect to the V-groove. For example, a mounting board made of a marker is used. However, this method requires less time for mounting, but the optical coupling efficiency may deteriorate depending on the mounting guide accuracy such as the V-groove and the mounting accuracy of the light emitting element.

  In addition, there is a method called “active alignment” in which a light emitting element is actually made to emit light and a lens is positioned at a position where the maximum output (maximum coupling efficiency) is obtained. In this method, for example, YAG welding described in Patent Document 2 is used to fix the lens to the carrier described above. However, in this method, it takes time to mount the lens, and the number of parts is also large. This increases the module size and costs.

Patent Document 3 describes a method of fixing with an adhesive while positioning a lens. In this method, a lens is temporarily placed on the lens mounting surface, a camera is placed at a predetermined distance from the lens, a light emitting element is actually made to emit light, and a condensing spot by the lens is taken at a predetermined position on the monitor. The lens is aligned so as to match the above.
Japanese Patent Laid-Open No. 11-344643 JP-A-9-178986 JP 2003-168838 A

  However, with the conventional lens mounting method, alignment in the height direction is impossible. In other words, the lens is mounted on the carrier, and the height position depends on the positional relationship (part dimensional accuracy) between the light emitting element and the lens mounting surface, and the adjustment allowance cannot be secured. May not coincide with the center of As a result, the maximum coupling efficiency cannot be obtained.

  In addition, the adhesive that fixes the lens diffuses to the mounting surface (lateral direction) of the L carrier, and the required amount of adhesive cannot be managed, making the adhesive to the lens non-uniform and solidifying or when temperature changes There are also problems such as deformation of the bonded portion and displacement.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an optical module on which an accurately aligned lens is mounted.

  The optical module of the present invention is an optical module in which a semiconductor laser, a lens that collimates light emitted from the semiconductor laser, and a lens holder that holds the lens are mounted on a carrier. And an adhesive for fixing the lens holder is regulated by the frame. According to this configuration, since the adhesive for fixing the lens holder is regulated by the frame, it is possible to prevent the diffusion of the adhesive and manage the amount of adhesive necessary for alignment in the height direction. It is possible to provide an optical module on which an accurately aligned lens is mounted.

  The optical module of the present invention is an optical module in which a semiconductor laser, a lens for collimating light emitted from the semiconductor laser, and a lens holder for holding the lens are mounted on the carrier. The carrier is mounted on the carrier. An adhesive for fixing the lens holder to the carrier is regulated by the recess. According to this configuration, since the adhesive for fixing the lens holder is regulated by the concave portion, it is possible to prevent the diffusion of the adhesive and manage the amount of adhesive necessary for the alignment in the height direction. It is possible to provide an optical module on which an accurately aligned lens is mounted.

  In the optical module of the present invention, a semiconductor laser and a lens for collimating the light emitted from the semiconductor laser are mounted on a carrier via a lens holder for holding the lens and a mounting holder for mounting the lens holder. In the optical module, the mounting holder has a pair of pillar portions and a connecting portion that connects the pillar portions, and one surface of the connecting portion is fixed to the carrier, and the other surface of the connecting portion is The lens holder is fixed to a space formed by a pair of pillars via an adhesive. According to this configuration, the lens holder is fixed to the mounting holder having the above configuration via an adhesive, thereby preventing the diffusion of the adhesive and managing the amount of adhesive necessary for alignment in the height direction. Therefore, it is possible to provide an optical module on which an accurately aligned lens is mounted.

  According to the optical module of the present invention, it is possible to control the amount of adhesive necessary for alignment in the height direction by preventing the diffusion of the adhesive. Modules can be provided.

  FIG. 1 shows a butterfly type package 1 according to an embodiment of the present invention. A semiconductor laser 11 as a light source and a collimating lens (hereinafter referred to as “first lens”) 12 are provided inside a housing 10. Mounted on the carrier 13.

  A nose 20 to which a ferrule can be fitted is attached to the housing 10 on the first side wall surface 10A. A lead pin 102 is disposed on the second side wall surface 10B facing the first side wall surface 10A. The lead pin 102 is prepared for giving a high frequency modulation signal to the internal semiconductor laser 11. Furthermore, lead pins 103 are also arranged on the third side wall surface 10C intersecting with the first side wall surface 10A and the second side wall surface 10B. It is used for input / output of DC or low frequency signals such as power supply, temperature sensor output, monitor PD element output, etc.

  In the casing 10, the bottom plate 10D is made of a highly heat conductive material such as CuW (copper tungsten alloy). The bottom plate 10D and the side wall surfaces 10A, 10B, 10C are assembled by brazing, and airtightness is ensured. The side wall surface is made of, for example, a metal such as Kovar and a laminated ceramic. A multilayer wiring is formed on the surface and inside of the multilayer ceramic, and electrical connection between various optical components and electrical components arranged inside the housing 10 and lead pins 101 and 102 arranged on the side wall surface of the housing 10 is performed. Used for secure connection.

  An electronic cooler 10F is mounted on the base 10E of the bottom plate 10D, and the carrier 13 is mounted thereon. As shown in FIG. 2, the carrier 13 has a first mounting surface 13A and a second mounting surface 13B on which a lens parallel to the first mounting surface 13A is mounted. On the first mounting surface 13A of the carrier 13, an EA-DFB device (a device in which an electroabsorption (EA) modulator and a distributed feedback semiconductor laser are monolithically integrated) 11 is mounted, and on the second mounting surface 13B, The first lens 12 is mounted.

  A multilayer ceramic substrate layer (not shown) is stacked on the first mounting surface 13A, and a PD carrier on which the EA-DFB device and the monitor PD are fixed is mounted on the uppermost layer. The wiring pattern on the PD carrier is electrically connected to the wiring pattern on the multilayer ceramic substrate layer with a bonding wire.

  On the second mounting surface 13B of the carrier 13, a first lens (rectangular aspheric lens) 12 for producing collimated light is disposed, and a nose 20 (see FIG. 1 (B)) in front of the exterior of the housing 10. Has a second lens 21 for condensing light (not shown). For fixing the first lens 12 to the mounting surface, an adhesive B (a type in which ultraviolet rays and heat are used in combination) is used as an adhesive capable of intentionally controlling the curing.

  Next, a lens mounting apparatus to which the lens mounting method of the present invention is applied will be described. Here, a case where the first lens 12 of the present embodiment is mounted while being aligned will be described. The first lens 12 is held by the suction collet C as shown in FIG. 3 and transferred to a mounting position where the adhesive B (see FIG. 2) is applied. The first lens 12 is mounted at a position where collimated light can be generated when the laser light emitted from the semiconductor laser 11 passes through the first lens 12.

  Therefore, in this embodiment, a lens alignment device 100 (details will be described later) as shown in FIG. 4A is used to confirm the lens mounting position. The lens alignment device 100 includes a dummy package 110 on which the first lens 12 is mounted, a package fixing base 160 on which the dummy package 110 is placed, and an infrared camera that is disposed at a position sufficiently away from the position of the package fixing base 160. 130, a helium-neon (He-Ne) laser 140, and a two-hole slit (pinhole) 150. The infrared camera 130 performs alignment while confirming the position of collimated light and its beam shape. The first lens 12 is mounted.

  The He-Ne laser 140 is disposed at the last stage of the lens alignment system constituting the lens alignment apparatus 100, and adjusts the lens alignment system using the laser beam of the He-Ne laser 140 as a reference of the optical axis L. To do. The two-hole slit 150 is arranged in front of the He—Ne laser 140. The dummy package 110 is disposed in front of the two-hole slit 150. Pin holes (through holes) are provided on both surfaces of the dummy package 110. The infrared camera 130 is arranged at a rear stage sufficiently away from the dummy package 110, and a cross mark is provided on the monitor 130A to observe the laser light that has passed through the pinhole of the dummy package 110. If the laser beam is projected at the center of the monitor 130A, the infrared camera 130 can be aligned with the optical axis L.

  After adjusting the lens alignment system as described above, the actual housing 10 is fixed to the package fixing base 160 as shown in FIG. And the light radiate | emitted from the semiconductor laser 11 (refer FIG. 1) accommodated in the housing 10 is collimated by the 1st lens 12 (refer FIG. 1), and is observed with the front infrared camera 130. FIG. If the shape of the laser light projected on the monitor 130A of the infrared camera 130 is located at the center of the monitor and the spot shape is not distorted, it can be understood that the collimated light has no axial deviation. Lens alignment in any of the X, Y, and Z directions is possible by such a method.

  As shown in FIG. 4C, the first lens 12 can be aligned with the semiconductor laser 11 by moving the first lens 12 in the XYZ directions. Since the first lens 12 is fixed by the suction collet C, the first lens 12 can be disposed at a desired position by moving together with the suction collet C.

  The above mounting method enables triaxial alignment of X, Y, and Z with respect to the first lens 12, but when the lens 12 is directly mounted on the surface of the carrier 13, a gap is formed in the Y (height) direction. There may be gaps. It is possible to float the lens 12 and fix it with an adhesive. However, since the adhesive diffuses on the mounting surface, it is difficult to manage the amount of the adhesive and to manage the viscosity of the adhesive. .

  FIG. 5 shows a first embodiment, where (A) shows a side view and (B) shows a perspective view. As shown in FIG. 5, a wall frame 14 is provided on the second mounting surface 13 </ b> B of the carrier 13 on which the first lens 12 is mounted. The wall frame 14 is filled with an appropriate amount of adhesive B for fixing a lens holder 120 described later. The first lens 12 is held by a lens holder 120 as shown in FIG. A pedestal 121 that supports the lens holder 120 is provided below the lens holder 120.

  In the present embodiment, the wall frame 14 is provided on the second mounting surface 13B of the carrier 13, the adhesive B is put therein, and the pedestal 121 is supported inside the wall frame 14 filled with the adhesive B. The lens holder 120 is placed. After aligning the first lens 12, the adhesive B is solidified. Since the adhesive B is restricted from being diffused in the horizontal direction by the wall frame 14, the amount of the adhesive B can be easily managed. Further, when the adhesive B is solidified, the pedestal 121 that supports the lens holder 120 receives a uniform tension in the horizontal direction, so that there is little displacement in the horizontal direction when the adhesive B is solidified.

  In addition, the structure which mounts the lens holder 120 in the hollow filled with the adhesive agent B in which the hollow is provided in the 2nd mounting surface 13B, the adhesive agent B is injected into the hollow may be sufficient.

  FIG. 7 shows a second embodiment. In the present embodiment, on the second mounting surface 13B of the carrier 13, a mounting holder 16 having a pair of column portions and a connecting portion that connects these column portions is provided. The mounting holder 16 is fixed on the second mounting surface 13B with one surface of the connecting portion by fixing means such as AuSn solder. The lens holder 120 is mounted in a space surrounded by the other surface of the connecting portion and the column portion, and the mounting holder 16 and the lens holder 120 are fixed with an adhesive.

  As shown in FIG. 7A, the interval W1 between the column portions of the mounting holder 16 is wider than the width dimension (W2) of the lens holder 120. As shown in FIG. 5B, the gap d formed between the mounting holder 16 and the lens holder 120 is set to a width that allows the adhesive B at the bottom to enter by capillary action. By solidifying the adhesive B surrounding the lens holder 120 and mounting the lens holder 120 on the mounting holder 16, the adhesive application amount is made uniform, and when the adhesive B is cured, the adhesive B contracts at high temperatures. It is possible to prevent the lens from being displaced due to stress such as expansion.

  In addition, when the lens holder 120 is inserted into the mounting holder 16, the lens holder 120 does not slip out in the Z (lens thickness) direction and drop off in the adhesive B between the lens holder 120 and the mounting holder 16. Some surface force is generated.

  When the first lens 12 is mounted in the mounting holder 16, first, an appropriate amount of adhesive B is dropped onto the space portion of the mounting holder 16 as shown in FIG. Next, when the first lens 12 is lowered to the groove portion together with the suction collet C and comes into contact with the liquid surface of the adhesive B, as shown in FIG. And the mounting holder 16 are uniformly wound around. In this state, the first lens 12 is aligned, and then the adhesive B is solidified.

  According to the mounting method, since the adhesive B is regulated by the lens holder 120 and the mounting holder 16, the amount and viscosity of the adhesive B can be easily managed. In addition, since the lens holder 120 receives a uniform tension on the three surfaces surrounded by the adhesive B, it is possible to avoid the concentration of strain in only one direction, and there is little deviation during solidification.

  In both Embodiments 1 and 2, the lens may be a first lens of a two-lens optical system (a lens that converts to collimated light) or a condensing lens of a one-lens system. In the above embodiment, a collimating lens having a non-rectangular outer shape is used. However, a ball lens or a dice block lens may be used.

  In addition, since the entrance of the adhesive can be restricted by this hook by providing the hook extending the upper part of the lens holder 120 on both sides, the adhesive adheres to the suction collet C that holds the hook. Can be prevented.

1 shows a butterfly package (BTF) according to an optical transmission device according to an embodiment of the present invention, (A) is an external perspective view, (B) is a broken perspective view, and (C) is a plan view showing a bottom part, (D) is a sectional view. Explanatory drawing which shows the mounting state of the semiconductor laser and the 1st lens inside the BTF package which concern on embodiment of this invention. (A) is a perspective view which shows the adsorption collet etc. which transfer the light emitting element concerning embodiment of this invention, (B) is the top view. (A) is explanatory drawing which shows the structure of the lens alignment apparatus used for the mounting method of this invention, (B) is explanatory drawing which shows the mounting method of the lens centered with the lens alignment apparatus, (C) is light emission. Explanatory drawing which shows the coincidence state of an element and the center of a lens. (A) is a side view showing a first embodiment of the present invention, (B) is a perspective view thereof. (A) is a front view which shows the lens holder used for 1st Example of this invention, (B) is the side view. (A) And (B) is explanatory drawing which shows the lens mounting method in 2nd Example of this invention. Explanatory drawing which shows the conventional BTF.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Butterfly type package 10 Package 10E Base part 10F Electronic cooler 11 Semiconductor laser 12 Lens (1st lens)
13 Carrier 13A First mounting surface (laser mounting surface)
13B Second mounting surface (lens carrier surface)
14 Wall frame 16 Mounting holder 120 Lens holder 121 Base 130 IR camera 140 Helium-neon (He-Ne) laser 150 Two-hole slit (pinhole)
160 Package fixing base B Adhesive C Adsorption collet

Claims (3)

In an optical module on which a semiconductor laser, a lens for collimating light emitted from the semiconductor laser, and a lens holder for holding the lens are mounted on a carrier,
Furthermore, the optical module has a frame on the carrier, and an adhesive for fixing the lens holder is regulated by the frame. In an optical module on which a semiconductor laser, a lens for collimating light emitted from the semiconductor laser, and a lens holder for holding the lens are mounted on a carrier,
The optical module has a recess in which the lens holder is mounted, and an adhesive that fixes the lens holder to the carrier is regulated by the recess. In an optical module in which a semiconductor laser and a lens for collimating light emitted from the semiconductor laser are mounted on a carrier via a lens holder for holding the lens and a mounting holder for mounting the lens holder.
The mounting holder has a pair of pillars and a connecting part that connects the pillars, and one surface of the connecting part is fixed to the carrier, and the other surface of the connecting part and the pair of pillars An optical module in which the lens holder is fixed to a space to be formed via an adhesive.

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