JP2005024697A - Optical module, stress relaxation method for optical module and method for manufacturing optical module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain reliability by suppressing the degradation in the performance of an optical module due to a change in the temperature of the use environment and to improve durability by averting breakage of the optical module. <P>SOLUTION: A first collimating lens 21 and a second collimating lens 23 mounted on an Si substrate 11 are fixed at least to one point of the Si substrate 11 and are carried at least at one point with a degree of freedom of movement to the Si substrate 11 . <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to, for example, an optical module on which an optical component is mounted, and more particularly to an optical module used for optical communication.
[0002]
[Prior art]
In recent years, with the progress of optical communication technology, for example, data communication using an optical fiber can transmit and receive a large amount of information at high speed. In particular, new technologies such as optical multiplex communication have been introduced, and further increases in speed and capacity are being promoted. Under these circumstances, the need for optical modules that appropriately combine various optical components used in optical communications, such as optical fibers, lenses, laser diodes, etc., has been increasing, and active research and development has been conducted. ing.
[0003]
As a prior art of such an optical module, for example, there is an optical element module in which a groove is provided on a Si substrate, a spherical lens is positioned and fixed in the groove, and a predetermined wiring is formed on the Si substrate. It is disclosed (for example, see Patent Document 1). There are several types of such optical modules. Among them, a groove is formed on a Si wafer by micromachining (MEMS), which is a three-dimensional processing technique, and optical components such as optical fibers and lenses are formed on the grooves. A method of embedding and fixing is drawing attention as a method excellent in mounting accuracy and mass productivity. The substrate for the optical module formed by the MEMS is called a silicon optical bench (SiOB) and is put into practical use as one key device.
[0004]
Here, a configuration of a three-terminal filter module for WDM (Wavelength Division Multiplexing) will be described as a specific example of a conventional optical module using SiOB. FIG. 6 is a plan view illustrating a configuration of a WDM three-terminal filter module (hereinafter referred to as a filter module). As shown in FIG. 6, in the filter module 30, a trapezoidal groove 12 is formed in the center of the surface of the single crystal silicon substrate (Si substrate) 11 by anisotropic etching, and the trapezoidal groove 12 is sandwiched between the trapezoidal groove 12. A silicon optical bench (SiOB) 10 having two parallel V-shaped grooves 13a and 13b and a V-shaped groove 13c formed on the other side is used as a base. In the trapezoidal groove 12 of SiOB 10, the first collimating lens 21, the thin film filter 22, and the second collimating lens 23 are sequentially spaced from the side where the two V-shaped grooves 13 a and 13 b are formed. It is installed. An incident light optical fiber 24 is mounted in the V-shaped groove 13a, a reflected light optical fiber 25 is mounted in the V-shaped groove 13b, and a transmitted light optical fiber 26 is mounted in the V-shaped groove 13c.
[0005]
In such an optical module such as the filter module 30, the position and depth of the trapezoidal groove 12 and the V-shaped grooves 13a, 13b, 13c formed in the SiOB 10 can be formed with high accuracy by anisotropic etching, The optical components such as the lenses 21 and 23 and the optical fibers 24, 25, and 26 are mounted in the trapezoidal groove 12 and the V-shaped grooves 13a, 13b, and 13c so that they are automatically aligned. It has the advantage of high efficiency.
[0006]
[Patent Document 1]
JP 2002-162542 A (3rd to 4th pages, FIG. 7)
[0007]
[Problems to be solved by the invention]
By the way, in the conventional optical module as shown in FIG. 6, when mounting optical components such as the first collimating lens 21, the thin film filter 22, and the second collimating lens 23 in the trapezoidal groove 12 formed in the SiOB 10. After adjusting and aligning the optical axis of the optical component, the optical properties are maintained over a long period of time while maintaining this state with high accuracy, so that it has high hardness like metal such as resin adhesive and solder. It is necessary to fix firmly using a strong material. FIG. 7 is a cross-sectional view taken along the line AA ′ of the filter module 30 shown in FIG. 6. In order to firmly fix the optical component and the SiOB 10, as shown in FIG. 7, for example, the first collimating lens 21 and the SiOB 10 In this joint portion, a method of adhering and fixing between the first collimating lens 21 and the trapezoidal groove 12 with an adhesive layer 15 that is entirely filled with a resin adhesive, solder, or the like has been adopted.
[0008]
However, in the method of filling and fixing a resin adhesive, solder, or the like entirely between the optical component and the trapezoidal groove 12, a material (for example, optical glass) constituting the optical component and silicon constituting the SiOB 10 ( Since the thermal expansion coefficients of Si) are different from each other, when they are placed in a high temperature or low temperature environment, a difference occurs in the amount of expansion / contraction between the optical component and SiOB 10 and stress is generated at the joint between the two. . Therefore, there has been a problem that the optical properties of the optical component are affected, such as a change in the refractive index and birefringence of the optical component due to the photoelastic effect, and the performance of the optical module is degraded. Further, the stress generated at the joint between the optical component and the SiOB 10 causes a problem that the SiOB 10 is cracked to break the optical module.
[0009]
Further, there is a problem that stress remains in the optical module due to a so-called heat cycle in which the temperature is repeatedly raised and lowered, and the optical characteristics of the optical module are not restored even when the temperature returns to room temperature.
In addition, when an optical component such as the first collimating lens 21 is fixed to the trapezoidal groove 12 of the SiOB 10 with a resin adhesive or solder, it occurs when the adhesive or solder is solidified if the area of the adhesive surface is large. Due to the shrinkage, there were problems such as changes in optical properties of optical components, displacement of the installation position, and cracks in the SiOB 10.
[0010]
Conventionally, in order to avoid the above-described problems, each material is selected so that the thermal expansion coefficient between members to be bonded, such as an optical component and a substrate such as SiOB10, is as close as possible. Measures have been taken to relieve the stress generated, but optical components, in particular, need to specify the physical properties of the materials based on their optical properties, so there are limits to the choice of materials. It was difficult to relieve the stress generated during
[0011]
The present invention has been made in order to solve the technical problems as described above, and the object of the present invention is to maintain the reliability by suppressing the performance degradation of the optical module due to the temperature change of the use environment. In addition, the durability of the optical module is improved by avoiding damage to the optical module.
[0012]
[Means for Solving the Problems]
For this purpose, in the optical module of the present invention, the optical component mounted on the substrate is fixed at least at one location with respect to the substrate and is supported at least at one location with a degree of freedom of movement. It is a feature. As a result, the stress generated between the optical component and the substrate can be relieved to maintain the performance of the optical module and to prevent the optical module from being damaged. Here, the optical component may be characterized in that it is fixed with an adhesive at least at one place with respect to the substrate or fixed with solder. With this configuration, it is possible to carry the optical component on the substrate and maintain the relative position between the two. In addition, the optical component may be in contact with the substrate in a state where it is placed at least at one place, or may be bonded by a deformable bonding member. In this configuration, it is possible to freely cause expansion / contraction between the optical component and the substrate when the temperature of the use environment changes, and it is possible to realize relaxation of stress generated between the two.
[0013]
The optical module of the present invention includes a substrate having a recess and an optical component that is supported by the plurality of contact portions and mounted on the substrate in the recess, and at least one of the plurality of contact portions is a substrate. And at least 1 does not fix the substrate and the optical component. Thereby, the stress generated between the optical component and the substrate can be relaxed. Here, if the concave portion is a groove having a trapezoidal or V-shaped cross section, the optical component is excellent in that the installation position can be automatically determined by being mounted in the groove. Furthermore, if the contact part is formed at least on both sides of the recess, the stress relaxation effect is particularly great.
[0014]
On the other hand, if the present invention is regarded as a stress relaxation method for an optical module, an optical component is placed in the recess of the substrate on which the recess is formed, and at least one contact portion between the optical component and the recess is fixed. It is characterized by relieving the stress generated in the optical component and the substrate by not fixing at least one other place. Thereby, while maintaining the performance of an optical module, it becomes possible to avoid the damage of an optical module. Here, if the optical component is fixed to the substrate at least on one side of the recess, it is preferable in that it is easy to determine the installation position of the optical component and to fix the substrate and the optical component. . Further, if the optical component is not fixed to the substrate at least on one side of the recess, it is excellent in that the installation position of the optical component can be determined and the stress generated in the optical component and the substrate can be efficiently relaxed. ing.
[0015]
On the other hand, if the present invention is regarded as an optical module manufacturing method, a groove forming step for forming a groove in a single crystal silicon substrate by anisotropic etching, and an optical component mounting for mounting an optical component in the groove formed by the groove forming step. And fixing at least one contact portion between the optical component placed by the placing step and the optical component placing step and the groove formed by the groove forming step, and the optical component and the substrate are fixed to at least one contact portion. And an optical component bonding step that is formed so as to be movable. Here, if the optical component bonding step is characterized in that an ultraviolet curable resin is applied to the fixed contact portion and the ultraviolet curable resin is irradiated with ultraviolet rays, for example, the optical component and the substrate can be easily and firmly bonded. Is preferable in that it can be fixed. In addition, if the optical component joining step is characterized in that a solder ball is placed on the fixed contact portion and the solder ball is irradiated with laser light, the optical component is unlikely to generate shrinkage stress due to solidification of the solder. Therefore, it is particularly excellent in that the optical accuracy as a module can be increased.
Further, the optical component joining step may be characterized in that the contact portion formed so that the optical component and the substrate can move is formed only by placing the optical component on the substrate. Thereby, the stress generated between the optical component and the substrate can be easily relaxed.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
[Embodiment 1]
1 and 2 are diagrams showing a configuration of a three-terminal filter module 1 for WDM (Wavelength Division Multiplexing) as an optical module to which the present embodiment is applied. A WDM three-terminal filter module (hereinafter referred to as a filter module) is one of the modules used for wavelength division multiplexing optical communication, and is a module that selectively extracts only a specific wavelength. FIG. 1 is a plan view of the filter module 1, and FIG. 2 is a cross-sectional view of the filter module 1 XX ′.
The filter module 1 to which the present embodiment is applied includes a trapezoidal groove 12 at the center of the surface of a Si substrate 11 that is a silicon wafer, and two parallel V-shapes on one side across the trapezoidal groove 12. The silicon optical bench (SiOB) 10 in which the mold grooves 13a and 13b and the V-shaped groove 13c are formed on the other side is disposed in the trapezoidal groove 12 of the SiOB 10 and the two V-shaped grooves 13a, A first collimating lens 21, a thin film filter 22, a second collimating lens 23, and an incident-light optical fiber 24 mounted in the V-shaped groove 13a, which are mounted in order from the side on which 13b is formed; The optical fiber 25 for reflected light mounted in the V-shaped groove 13b and the optical fiber 26 for transmitted light mounted in the V-shaped groove 13c are provided.
[0017]
As shown in FIG. 2, the filter module 1 to which the present embodiment is applied includes the SiOB 10 in which the first collimating lens 21 and the second collimating lens 23 and the trapezoidal groove 12 each have two contact portions P. In this embodiment, the first collimating lens 21 and the second collimating lens 23 and the trapezoidal groove 12 are joined together by the first collimating lens 21 and the second collimating lens 23 and the trapezoidal groove 12. The two contact portions P and Q are fixed at one contact portion P, and at the other contact portion Q, the relative positions of the first collimating lens 21 and the second collimating lens 23 and the trapezoidal groove 12 are fixed. It is characterized in that it is supported with a degree of freedom of movement so that it can be displaced.
[0018]
The SiOB 10 includes a trapezoidal groove 12 in which the first collimating lens 21, the thin film filter 22, and the second collimating lens 23 are mounted, a V-shaped groove 13 a in which the incident light optical fiber 24 is mounted, and an optical fiber 25 for reflected light. Are formed, and a V-shaped groove 13c in which the transmitted light optical fiber 26 is mounted is formed.
Here, the manufacturing method of SiOB10 is demonstrated. In the SiOB 10, an oxide layer is first formed on the surface of the Si substrate 11 whose crystal plane is the (100) plane. The thickness of the oxide layer is determined by the design value of the depth of the trapezoidal groove or the V-shaped groove. A typical value is 2 μm.
Next, a photoresist is applied on the Si substrate 11. Here, as the photoresist, for example, OEPR-800 manufactured by Tokyo Ohka Kogyo Co., Ltd. having a viscosity of 50 cp is used, and the Si substrate 11 is applied while rotating at a rotational speed of 1500 rpm. The coating thickness is typically 6 μm.
[0019]
After applying a photoresist to the Si substrate 11, pre-baking is performed at 110 ° C. for 2 minutes to cure the photoresist. Then, contact exposure is performed using a chromium (Cr) photomask. Here, ultraviolet light having a wavelength of 350 to 400 nm is used as exposure light.
Next, the exposed Si substrate 11 is developed with a developer. As the developer, for example, an alkaline solution of NMD-3 manufactured by Tokyo Ohka Kogyo Co., Ltd. is used. In this development step, since a positive resist is used as the above-mentioned photoresist, the photoresist in the exposed portion is removed. Further, post-baking is performed at 120 ° C. for 5 minutes.
[0020]
Thereafter, dry etching is performed with a fluorine-based gas to remove the Si oxide film in a region not covered with the photoresist. Further, the photoresist is dissolved and removed with acetone.
Etching is then performed with an aqueous potassium hydroxide (KOH) solution (30 to 35 wt%, 60 to 70 ° C.). The etching rate of pure Si is about two orders of magnitude faster than the etching rate of Si oxide film. For this reason, in the etching region, the (111) plane of the Si crystal plane appears on the surface, and a V-shaped or trapezoidal groove having an inclination angle of 54.7 ° is formed. Note that TMAH (tetramethyl ammonium hydroxide solution) may be used as the etching solution.
In this way, the SiOB 10 in which the trapezoidal groove 12 and the V-shaped grooves 13a, 13b, 13c are formed is manufactured. Here, the trapezoidal groove 12 is formed wide so that the thin film filter 22 can be disposed in a portion where the thin film filter 22 is disposed.
The process as described above is called anisotropic etching, and is an important technique for realizing MEMS (Micro Electro Mechanical Systems).
[0021]
In the filter module 1 using the SiOB 10, the incident light optical fiber 24 mounted in the V-shaped groove 13 a of the SiOB 10 transmits light in which a plurality of different wavelengths are multiplexed and emits the light to the first collimating lens 21. To do.
The first collimating lens 21 is an aspherical phase lens in which the curvature of the lens surface is different between the central portion and the peripheral portion, and is manufactured by press molding with a mold using the optical glass BK-7 as a material. Then, the light incident from the optical fiber 24 for incident light is converted into parallel light and emitted to the thin film filter 22.
The thin film filter 22 is a thin film filter element in which a dielectric thin film is laminated in a multilayer on a glass substrate by a process such as sputtering or vacuum deposition, and has a predetermined wavelength λ. _m The wavelength λ _m It has a function of reflecting other light. The thin film filter 22 has a wavelength λ. _m Is transmitted to the second collimating lens 23, and the wavelength λ _m Light other than those is reflected and emitted to the first collimating lens 21.
[0022]
The second collimating lens 23 is configured in the same manner as the first collimating lens 21. Then, the wavelength λ transmitted through the thin film filter 22 _m Is condensed on the end face of the transmitted light optical fiber 26, and the wavelength λ is transmitted to the transmitted light optical fiber 26. _m Guide the light.
On the other hand, the wavelength λ reflected by the thin film filter 22 _m The other light is condensed on the end face of the reflected light optical fiber 25 by the first collimating lens 21 and the wavelength λ is reflected on the reflected light optical fiber 25. _m Non-guided light.
[0023]
Next, the joining of the first collimating lens 21 and the second collimating lens 23 and the SiOB 10 which are features of the filter module 1 of the present embodiment will be described.
As described above, when a groove is formed in the Si substrate 11 by anisotropic etching, a (111) plane of the Si crystal plane appears on the slope of the formed groove, and a trapezoid with an inclination angle of 54.7 °. A mold groove 12 and V-shaped grooves 13a, 13b, 13c are formed. Therefore, when an optical component having a circular cross section such as the first collimating lens 21 and the second collimating lens 23 is placed in the trapezoidal groove 12, as shown in FIG. 2, the first collimating lens 21 and the second collimating lens 21 are disposed. The lens 23 and the trapezoidal groove 12 abut at two contact portions P and Q of the inclined surfaces 12b and 12c of the trapezoidal groove 12. For example, depending on the size and shape of the trapezoidal groove 12 including the well type and the optical component, there are cases where the contact is made at three or more locations including the contact with the bottom surface 12a.
The contact portions P and Q between the first collimating lens 21 and the second collimating lens 23 and the SiOB 10 are lines parallel to the optical axes of the first collimating lens 21 and the second collimating lens 23. And the installation position of the 1st collimating lens 21 and the 2nd collimating lens 23 is determined by these two contact parts P and Q.
[0024]
In the present embodiment, the first collimating lens 21 and the second collimating lens 23 and the SiOB 10 are fixed by the adhesive layer 14 in one of the two contact portions P and Q, and the other contact portion. In Q, the first collimator lens 21 and the second collimator lens 23 are supported with a degree of freedom of movement so that the relative positions of the SiOB 10 can be shifted. That is, both are fixed at one contact portion P and are not displaced relative to each other, but are supported at the other contact portion Q so that they can be displaced relative to each other.
[0025]
The first collimating lens 21 and the second collimating lens 23 and the SiOB 10 are fixed by the adhesive layer 14 at the contact portion P. The adhesive layer 14 is used to rotate the first collimating lens 21 and the second collimating lens 23. After the optical axis is adjusted by translation and the installation position is determined, an ultraviolet curable resin is applied using, for example, a microdispenser, and is formed by condensing and irradiating ultraviolet rays. By this adhesive layer 14, the first collimating lens 21, the second collimating lens 23 and the SiOB 10 are integrally fixed to each other. The ultraviolet curable resin has an advantage that it is easy to apply because of its low viscosity, and has good workability because it does not require heat for curing.
Here, as the ultraviolet curable resin, epoxy-modified acrylate type, polyurethane type, polyester type, etc. can be used. In addition to the ultraviolet curable resin, thermosetting resins such as epoxy resin, phenol resin, melamine resin, etc. It can also be used.
[0026]
On the other hand, in the contact portion Q, the adhesive layer is not formed, and the first collimating lens 21 and the second collimating lens 23 and the SiOB 10 are held in a state of being in contact without being fixed.
In addition, although it can also be set as the structure joined by the joining member also in the contact part Q, the material used for a joining member in that case is a thing stable in the state which has predetermined | prescribed elasticity. Here, the predetermined elasticity means that the first collimating lens 21 and the second collimating lens 23 and the SiOB 10 are free according to the difference in the expansion / contraction amount due to the temperature change of the use environment. It means that it can be deformed to such an extent that it can be moved.
By configuring the contact portion Q in this way, the first collimating lens 21 and the second collimating lens 23 and the SiOB 10 are not fixed in the contact portion Q, and move so that each of them can be displaced relative to each other. It is supported with a degree of freedom.
[0027]
In this way, the first collimating lens 21 and the second collimating lens 23 and the SiOB 10 are fixed by the adhesive layer 14 in one contact portion P, and the contact portion Q is supported with a degree of freedom of movement in the other contact portion Q. P supports the first collimating lens 21 and the second collimating lens 23 on the SiOB 10 and maintains the relative position between them. On the other hand, the contact portion Q is displaced due to expansion / contraction when the temperature of the use environment changes. It can be generated freely.
[0028]
That is, the thermal expansion coefficient of the optical glass BK-7 constituting the first collimating lens 21 and the second collimating lens 23 is 7.1 × 10. ^-6 / Deg, and the thermal expansion coefficient of silicon (Si) constituting the Si substrate 11 of SiOB10 is 2.5 × 10 ^-6 / Deg, both of which have different coefficients of thermal expansion. Therefore, when the first collimating lens 21 and the second collimating lens 23 and the SiOB 10 are fixed by the adhesive layer at both the contact portions P and Q, the first collimating lens 21 and the second collimating lens 23 are caused by temperature fluctuations. There is a difference in the amount of expansion / contraction from the Si substrate 11. For example, if the use environment temperature changes from room temperature (20 ° C.) to 70 ° C., a difference in expansion amount in submicron units occurs between the two.
[0029]
As a result, a large force due to the volume variation difference is applied to both the fixed members, internal stress is generated in the first collimating lens 21 and the second collimating lens 23, and the refractive index and birefringence change due to the photoelastic effect. As a result, the optical properties are affected and the performance of the filter module 1 is degraded. Further, in the SiOB 10, the bottom portion 16 of the groove 12 is formed thin, and has a structure in which stress is easily concentrated when receiving the force from the wall surface portions on both sides of the trapezoidal groove 12. Therefore, the bottom portion 16 of the trapezoidal groove 12 is easily distorted, and when the distortion repeatedly occurs, a crack is generated and the filter module 1 is damaged.
[0030]
On the other hand, in the filter module 1 of the present embodiment, the first collimating lens 21 and the second collimating lens 23 and the SiOB 10 expand and contract even when the temperature of the use environment changes in one contact portion Q. Because it is configured so that it can be freely generated, even if different expansion and contraction amounts occur in both due to temperature fluctuations, each can expand and contract freely, so that stress is applied to both. Can be suppressed. That is, at the contact portion Q, as shown in FIG. 2, the first collimating lens 21 and the second collimating lens 23 can move in the direction of the arrow S according to the expansion / contraction, and the SiOB 10 can be moved to the arrow. It can move in the direction of T. For this reason, even if a volume variation difference occurs between them, the stress is released by the movement of each, and the force applied to the first collimating lens 21 and the second collimating lens 23 and the Si substrate 11 becomes extremely small. In addition, each position shift generated in the contact portion Q can return to the original position when the use environment temperature returns to the normal temperature.
In particular, since the contact portion P and the contact portion Q are located on opposite sides of the trapezoidal groove 12, when the contact portion P is fixed, the amount of expansion / contraction at the farthest contact portion Q is large. Therefore, the stress relaxation effect due to the contact portion Q being carried with a degree of freedom of movement is great.
[0031]
As a result, since it is possible to suppress the occurrence of internal stress in the first collimating lens 21 and the second collimating lens 23, the performance of the filter module 1 can be maintained without affecting the optical properties. Further, in the case of SiOB 10, when the force from both sides of the trapezoidal groove 12 is received, the occurrence of cracks can be suppressed at the bottom 16 of the trapezoidal groove 12 where stress tends to concentrate, and the durability of the filter module 1 can be improved. It becomes.
[0032]
[Embodiment 2]
In the first embodiment, the filter module 1 in which the first collimating lens 21 and the second collimating lens 23 and the SiOB 10 are fixed using an adhesive at one of the two contact portions P and Q is shown as an example. And explained. However, the first collimating lens 21 and the second collimating lens 23 and the SiOB 10 can be fixed using solder. In the second embodiment, the case where the first collimating lens 21 and the second collimating lens 23 and the SiOB 10 are fixed using solder at one of the two contact portions P and Q will be described. . In addition, about the structure similar to Embodiment 1, the same code | symbol is used and the detailed description is abbreviate | omitted here.
[0033]
3 and 4 are diagrams for explaining the configuration of the filter module 2 to which the present embodiment is applied. FIG. 3 is a plan view of the filter module 2. FIG. 4 is a YY ′ sectional view of the filter module 2. It is. In the filter module 2 to which the present embodiment is applied, as in the first embodiment, a trapezoidal groove 12 and a trapezoidal groove 12 are sandwiched between the trapezoidal groove 12 at the center of the surface of the Si substrate 11 that is a silicon wafer. Are disposed in a silicon optical bench (SiOB) 10 having two parallel V-shaped grooves 13a and 13b and a V-shaped groove 13c formed on the other side, and a trapezoidal groove 12 of SiOB10. The first collimator lens 21, the thin film filter 22, the second collimator lens 23, and the V-shaped groove 13a mounted at predetermined intervals in order from the side where the V-shaped grooves 13a and 13b are formed. The optical fiber 24 for incident light, the optical fiber 25 for reflected light mounted in the V-shaped groove 13b, and the optical fiber 26 for transmitted light mounted in the V-shaped groove 13c are provided. A metal film (metallized film) 17 is formed on the surface of the SiOB 10 where the first collimating lens 21 and the second collimating lens 23 are mounted, and the side surfaces of the first collimating lens 21 and the second collimating lens 23. Metal films are also formed on 21a and 23a.
[0034]
Gold (Au), silver (Ag), nickel (Ni), copper (Cu), or the like can be used as a metal for forming the metal film 17. In forming the metal film 17, it is preferable to perform electroless plating because it can uniformly plate every corner of the trapezoidal groove 12 formed on the surface of the SiOB 10.
Moreover, about the 1st collimating lens 21 and the 2nd collimating lens 23, only the side surface which contact | abuts SiOB10 is coated with the metal film by electroless plating.
[0035]
Next, the joining of the first collimating lens 21 and the second collimating lens 23 and the SiOB 10 which are features of the filter module 2 of the present embodiment will be described. In the present embodiment, as shown in FIG. 4, the first collimating lens 21 and the second collimating lens 23 and the SiOB 10 at one of the two contact portions P and Q in the trapezoidal groove 12 of the SiOB 10. Are fixed with solder, and are supported with a degree of freedom of movement so that the relative positions of the first collimating lens 21 and the second collimating lens 23 and the SiOB 10 can be shifted at the other contact portion Q.
[0036]
The first collimating lens 21 and the second collimating lens 23 and the SiOB 10 are fixed by the solder layer 18 in the contact portion P. The solder layer 18 is rotated or translated by the first collimating lens 21 and the second collimating lens 23. After the installation position is determined by adjusting the optical axis, etc., a solder ball is placed in the vicinity of the contact portion P, and in this state, a carbon dioxide laser is condensed and irradiated in a pulsed manner on the solder ball, and the solder ball is instantaneously applied. It is formed by melting and cooling.
By adopting such a method for forming the solder layer 18, there is an advantage that the optical accuracy as a module can be increased because the shrinkage stress due to the solidification of the solder hardly occurs.
[0037]
On the other hand, in the contact portion Q, as in the first embodiment, the adhesive layer and the solder layer are not formed, and the first collimating lens 21 and the second collimating lens 23 and the SiOB 10 are not fixed and are in contact with each other. It is supported.
In addition, it can also be set as the structure joined using the joining member with predetermined | prescribed elasticity in the contact part Q. Here, the predetermined elasticity means that the first collimating lens 21 and the second collimating lens 23 and the SiOB 10 are free according to the difference in the expansion / contraction amount due to the temperature change of the use environment. It means that it can be deformed to such an extent that it can be moved.
Thus, as a joining member filled in the contact portion having the degree of freedom of movement, a material having a predetermined elasticity, for example, a silicone-based adhesive or a synthetic rubber-based adhesive can be used. In addition, in the above-described ultraviolet curable resin, thermoplastic resin, or various epoxy-based and acrylate-based adhesives, a material having a predetermined flexibility by adjusting the material composition or mixing other materials. They can be filled in the contact portion Q. Or it is also possible to give predetermined | prescribed elasticity by adjusting hardening conditions, such as hardening temperature, ultraviolet irradiation intensity | strength, and time, in each adhesive agent.
By configuring such a contact portion Q, the first collimating lens 21 and the second collimating lens 23 and the SiOB 10 are not fixed in the contact portion Q, and move so that each can shift relative positions. In addition to being supported with a degree of freedom, it is possible to prevent foreign matter and the like from entering the contact portion Q having a degree of freedom of movement, and to keep module performance stable.
[0038]
As described above, the first collimating lens 21 and the second collimating lens 23 and the SiOB 10 are fixed by the solder layer 18 in the one contact portion P, and the contact portion P is supported by the other contact portion Q with a degree of freedom of movement. While supporting the first collimating lens 21 and the second collimating lens 23 on the SiOB 10 and maintaining the relative positions of them, the contact portion Q is free from displacement due to expansion / contraction of both when the temperature of the use environment changes. Can be generated. As a result, the generation of internal stress in the first collimating lens 21 and the second collimating lens 23 can be suppressed, so that the optical properties are not affected and the performance of the filter module 2 can be maintained. When the force from the wall surface portions on both sides of 12 is received, the occurrence of cracks is also suppressed at the bottom portion 16 of the trapezoidal groove 12 where stress tends to concentrate, and the durability of the filter module 2 can be improved.
[0039]
Here, the first contact portion P fixes the first collimating lens 21 and the second collimating lens 23 and the SiOB 10 by the adhesive layer 14 and the solder layer 18, and the other contact portion Q is supported with a degree of freedom of movement. The filter modules 1 and 2, the first collimating lens 21, the second collimating lens 23, and the SiOB 10 are bonded and fixed by an adhesive layer 15 in which an adhesive, solder, or the like is entirely filled between the trapezoidal grooves 12. The test which compares with the filter module 30 (refer FIG. 6, 7) of this was done.
In this test, a heat shock test was performed on the filter modules 1 and 2 of the present invention and the conventional filter module 30 to compare the durability. The test condition is to repeatedly perform a heat shock cycle in which each is left alternately in an environment of −20 ° C. and 90 ° C.
[0040]
The result is shown in FIG. As shown in FIG. 5, in the conventional filter module 30, the SiOB 10 was cracked and damaged in 20 heat shock cycles, whereas in the filter modules 1 and 2 of the present invention, both were 100 times. In the heat shock cycle, it was confirmed that no cracks were generated in the SiOB 10 and the stress generated in the module was considerably relaxed by the change in the use environment temperature, and the durability of the filter modules 1 and 2 was improved.
[0041]
As described above in detail, according to the filter modules 1 and 2 of the present embodiment, one of the two contact portions P and Q of the first collimating lens 21 and the second collimating lens 23 and the SiOB 10 is one of them. The contact portion P is fixed by the adhesive layer 14 or the solder layer 18, and the other contact portion Q is supported with a degree of freedom of movement, so that the contact portion P supports the first collimating lens 21 and the second collimating lens 23 on the SiOB 10. At the same time, while maintaining the relative position between the two, the contact portion Q can freely cause displacement due to expansion and contraction of both when the temperature of the use environment changes. As a result, the generation of internal stress in the first collimating lens 21 and the second collimating lens 23 can be suppressed, so that the performance of the filter modules 1 and 2 can be maintained without affecting the optical properties. The generation of cracks is suppressed even at the bottom 16 of the trapezoidal mold groove 12 where stress tends to concentrate when receiving the force from the wall surfaces on both sides of the mold groove 12, and the durability of the filter modules 1 and 2 can be improved. It becomes possible.
[0042]
In the first and second embodiments, the case where there are two contact portions between the optical components such as the first collimating lens 21 and the second collimating lens 23 and the SiOB 10 has been described as an example. However, there are three contact portions. The same applies to the above case, and the same effect can be obtained as long as the structure is fixed at at least one place and is supported at at least one place with a degree of freedom of movement.
In addition, although a description has been given by taking a WDM three-terminal filter module using SiOB10 as an example, the present invention can be applied to all modules configured by bonding substrates and components made of different materials, and in particular the temperature of the usage environment. This is excellent in that the reliability against changes can be improved.
Furthermore, the adhesive method and the solder have been described as examples of the bonding method, but it goes without saying that the present invention is not limited to this.
[0043]
【The invention's effect】
As described above, according to the present invention, it is possible to maintain the reliability by suppressing the performance deterioration of the optical module due to the temperature change of the use environment, and to improve the durability by avoiding the damage of the optical module. It becomes.
[Brief description of the drawings]
FIG. 1 is a plan view showing a configuration of a filter module of the present invention.
FIG. 2 is a cross-sectional view of the filter module of the present invention, taken along the line XX ′.
FIG. 3 is a plan view showing a configuration of a filter module of the present invention.
FIG. 4 is a YY ′ sectional view of the filter module of the present invention.
FIG. 5 is a diagram showing the results of a comparative test.
FIG. 6 is a plan view showing a configuration of a conventional filter module.
FIG. 7 is a cross-sectional view of a conventional filter module taken along line AA ′.
[Explanation of symbols]
1, 2, 30 ... Filter module, 10 ... Silicon optical bench (SiOB), 11 ... Si substrate, 12 ... Trapezoidal groove, 13a, 13b, 13c ... V-shaped groove, 14, 15 ... Adhesive layer, 16 ... Bottom: 17 ... Metal film (metallized film), 18 ... Solder layer, 21 ... First collimating lens, 21a ... First collimating lens side, 22 ... Thin film filter, 23 ... Second collimating lens, 23a ... Second collimating lens side , 24 ... Optical fiber for incident light, 25 ... Optical fiber for reflected light, 26 ... Optical fiber for transmitted light

Claims (15)

A substrate,
An optical component mounted on the substrate,
The optical module, wherein the optical component is fixed at least at one place with respect to the substrate, and is supported with at least one place on the substrate with a degree of freedom of movement. The optical module according to claim 1, wherein the optical component is fixed to the substrate by an adhesive at at least one location. The optical module according to claim 1, wherein the optical component is fixed to the substrate by solder at at least one location. The optical module according to claim 1, wherein the optical component is in contact with the substrate only in a state where it is placed at at least one location. The optical module according to claim 1, wherein the optical component is bonded to the substrate by a bonding member that can be deformed at least at one position. A substrate having a recess formed thereon;
An optical component carried by the plurality of contact portions in the recess and mounted on the substrate,
At least one of the plurality of contact parts fixes the substrate and the optical component, and at least one does not fix the substrate and the optical component. The optical module according to claim 6, wherein the recess is a groove having a trapezoidal shape or a V-shaped cross section. The optical module according to claim 6, wherein the contact portion is formed at least on both sides of the concave portion. An optical component is placed in the concave portion of the substrate in which the concave portion is formed, and at least one of the contact portions between the optical component and the concave portion is fixed, and at least the other one is not fixed. A stress relaxation method for an optical module, wherein stress generated in the optical component and the substrate is relaxed. The stress relaxation method for an optical module according to claim 9, wherein the optical component is fixed to the substrate at least on one side of the recess. 10. The stress relaxation method for an optical module according to claim 9, wherein the optical component is not fixed to the substrate at least on one side of the recess. A groove forming step of forming grooves in the single crystal silicon substrate by anisotropic etching;
An optical component placing step of placing an optical component in the groove formed by the groove forming step;
At least one contact portion between the optical component placed by the optical component placing step and the groove formed by the groove forming step is fixed, and at least one contact portion is fixed to the optical component and the substrate. And an optical component joining step for forming the optical module so as to be movable. The optical module manufacturing method according to claim 12, wherein in the optical component bonding step, an ultraviolet curable resin is applied to the abutting portion to be fixed, and the ultraviolet curable resin is irradiated with ultraviolet rays. The optical module manufacturing method according to claim 12, wherein in the optical component bonding step, a solder ball is placed on the contact portion to be fixed, and the solder ball is irradiated with a laser beam. The optical component bonding step includes forming the contact portion formed so that the optical component and the substrate can move only by placing the optical component on the substrate. Item 13. A method for producing an optical module according to Item 12.

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