JP5654316B2 - Optical module - Google Patents

Description

  The present invention relates to an optical module that transmits or receives an optical signal.

  With the increase in data communication speed and capacity, optical signal conversion using optical fibers (including optical waveguides) has become widespread in place of conventional electrical signal communication using metal cables.

  Optical signalization has advantages such as electromagnetic noise-less, high-speed, wideband isolated signal transmission, reduced wiring, etc., and in recent years, it has been dramatically expanded to in-device communication.

  In order to incorporate it into equipment, it is essential to reduce the size and height of the optical module. As a means to achieve this, an optical element (light-emitting element or light-receiving element) is mounted on a substrate and the optical path is converted directly below it. There is a module form in which the mirror part and an optical signal transmission optical fiber or an optical waveguide are integrated.

  For example, in the optical module shown in FIG. 12, a light receiving element substrate 53 supporting the light receiving element 52 is attached on the substrate 51, and a plurality of optical fibers 54 are connected to each V groove of the light receiving element substrate 53 for multi-channeling. Each optical fiber 54 is held by an optical fiber holding substrate 56 after being positioned by 55. Further, a reflection wall surface (mirror part) 56 b is formed in the concave groove 56 a of the optical fiber holding substrate 56. And the emitted light from each optical fiber 54 is reflected on the reflecting wall surface 56b and projected onto the light receiving element 52 (see Patent Document 1).

  Here, the optical signal propagating through each optical fiber 54 hardly leaks to the outside.

Japanese Patent Laid-Open No. 60-172004

  However, since each optical fiber (channel) 54 is optically connected by the concave groove 56a, the scattered component of the reflected light from the reflection wall surface (mirror part) 56b easily leaks (crosstalk) to the adjacent optical fiber 54. . Therefore, there has been a problem that it is impossible to cope with high-speed and large-capacity data communication and multi-channel to cope with bidirectional communication.

  The present invention has been made to solve the above problem, and an object of the present invention is to provide an optical module in which the scattering component of the reflected light of the mirror part can hardly leak (crosstalk) to an adjacent channel. .

In order to solve the above-described problems, the present invention provides an internal waveguide provided in a groove formed on the surface of a substrate, an optical path conversion mirror formed at the tip of the groove, and the mirror Light that is mounted on the surface of the substrate so as to face the substrate and emits an optical signal to the core portion of the internal waveguide via the mirror portion, or receives an optical signal from the core portion of the internal waveguide via the mirror portion In an optical module including an optical fiber having an element and a fiber core portion optically coupled to the core portion of the internal waveguide, the core portion is arranged in parallel in the groove, and the groove is A plurality of core parts are formed in a width that can be arranged at a constant pitch, the mirror part is formed corresponding to each core part, and the optical element is mounted corresponding to each mirror part, Is filled with cladding of the internal waveguide Te, in the groove in the vicinity of the mirror portion, the scattering component of the reflected light of the mirror portion is provided shielding portion for shielding so as not to be leaked to the core portion not corresponding is provided, the shield portion of the core portion to which the adjacent The optical module is formed of a part of a substrate left in the groove, and the substrate is a silicon substrate .

  The shielding part may be configured to extend in the direction of the optical fiber along the internal waveguide from the vicinity of the mirror part.

  An oxide film layer including the surface of the groove may be formed on the surface of the shielding part.

  The removal part of the oxide film layer may be formed on the surface of the shielding part.

  It can be set as the structure by which the light absorber along this shielding part is arrange | positioned on the surface of the said shielding part.

According to the present invention, in a multi-channel optical module in which a plurality of core portions are arranged in one groove, a core in which the reflected light scattering component of the mirror portion does not correspond in the groove near the mirror portion. The shielding part which shields so that it may not leak to a part is provided. Therefore, the shielding component makes it difficult for the scattered component of the reflected light from the mirror portion to leak (crosstalk) to the incompatible core portion, that is, the adjacent channel. As a result, it is possible to cope with an increase in the speed and capacity of data communication and an increase in the number of channels for supporting bidirectional communication. In addition, by arranging a plurality of core portions in one groove, the pitch of the core portions can be reduced, so that the optical module can be miniaturized.
In addition, the shielding part is formed by a part of the substrate left in the groove of the adjacent core part, and the substrate is a silicon substrate. Therefore, a smooth and high-precision mirror part and a raised shielding are obtained by etching. A groove having a portion can be formed simultaneously and easily.

1 is a schematic side view of an optical module according to the present invention. It is the 1st board | substrate of the optical module of the light emission side of FIG. 1, (a) is side surface sectional drawing, (b) is II sectional view taken on the line of (a), (c) is II-II line of (a). It is sectional drawing. 2A is a perspective view of the first substrate of FIG. 2, and FIG. 3B is a perspective view in which an internal waveguide is formed. FIG. 3A is a perspective view in which a light emitting element is mounted, and FIG. 3B is a perspective view in which an optical fiber is inserted. (A) is the perspective view which fixed the pressing block to the 1st board | substrate, (b) is the perspective view of an optical fiber. It is a perspective view of the 1st board | substrate which provided the shielding part. (A) is the III-III sectional view taken on the line of (b), (b) is a top view of the core part and clad part of FIG. (A) is sectional drawing of the 1st board | substrate which formed the oxide film layer in the shielding part, (b) is sectional drawing of the 1st board | substrate which formed the removal part of the oxide film layer of the shielding part. It is sectional drawing of the 1st board | substrate which has arrange | positioned the light absorber to the shielding part. It is a perspective view of the 1st substrate of a comparative example. (A) is the IV-IV sectional view taken on the line of (b), (b) is a top view of the core part and clad part of FIG. It is the conventional optical module, (a) is a perspective view, (b) is sectional drawing.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic side view of an optical module according to the present invention. 2 is a first substrate 1 of the light-emitting side optical module of FIG. 1, (a) is a side sectional view, (b) is a sectional view taken along line II of (a), and (c) is a sectional view of (a). It is II-II sectional view taken on the line. 3A and 3B show the first substrate 1. FIG. 3A is a perspective view, and FIG. 3B is a perspective view in which an internal waveguide 16 is formed. 4A and 4B show the first substrate 1, in which FIG. 4A is a perspective view in which the light emitting element 12a is mounted, and FIG. 4B is a perspective view in which the optical fiber 2 is inserted. FIG. 5A is a perspective view in which the holding block 24 is fixed, and FIG. 5B is a perspective view of the optical fiber 2.

  Here, FIGS. 1 to 5 are single-channel optical modules in which one core portion 17 is arranged in one first groove 1a of the first substrates 1 and 3, but FIGS. 5, the outline of the optical module will be described first. Thereafter, a multi-channel optical module in which a plurality of core portions 17 (A, B) according to the present invention are arranged in one first groove 1a of the first substrates 1 and 3 will be described with reference to FIGS. This will be described in detail.

  In FIG. 1, an optical module includes a first substrate (mount substrate) 1 on a light emitting side, a first (mount) substrate 3 on a light receiving side, and an optical fiber 2 that optically couples the first substrates 1 and 3. I have.

  The first substrates 1 and 3 need to have rigidity in order to avoid the influence of heat during mounting and the influence of stress due to the use environment. Further, in the case of optical transmission, since optical coupling efficiency from the light emitting element to the light receiving element is required, it is necessary to mount the optical element with high accuracy and to suppress position fluctuation during use as much as possible. For this reason, a silicon (Si) substrate is employed as the first substrates 1 and 3 in this embodiment.

  In particular, in the case of a silicon substrate, it is possible to process a highly accurate etching groove on the surface by utilizing the crystal orientation of silicon [a highly accurate mirror portion 15 (described later) using this groove, and an internal waveguide 16 ( (To be described later). ]. In addition, the silicon substrate has good flatness.

  The first substrates 1 and 3 are respectively installed on the surface (upper surface) of a second substrate (interposer substrate) 6 having a larger size. Connectors 7 for electrically connecting to other circuit devices are respectively attached to the back surface (lower surface) of each second substrate 6.

  On the surface (upper surface) of the first substrate 1, a light emitting element 12a that converts an electrical signal into an optical signal is flip-chip mounted with bumps 12c (see FIG. 2) with the light emitting surface facing downward. An IC substrate (signal processing unit) 4a on which an IC circuit for transmitting an electrical signal to the light emitting element 12a is formed is mounted on the surface of the second substrate 6.

  In the present embodiment, a surface emitting laser (VCSEL (Vertical Cavity Surface Emitting Laser)) that is a semiconductor laser is employed as the light emitting element 12a. The light emitting element 12a may be an LED or the like.

  The IC substrate 4a is a driver IC that drives the VCSEL, and is disposed in the vicinity of the light emitting element 12a. The light emitting element 12a and the IC substrate 4a are connected to a metal circuit (patterning circuit by copper or gold sputtering) formed on the surface of the first substrate 1 and the surface of the second substrate 6.

  On the surface of the first substrate 1, as shown in FIG. 3 (a), a substantially trapezoidal first groove (waveguide forming groove) 1a and a substantially V-shaped second deeper than the first groove 1a. The groove 1b is formed continuously in the front-rear direction.

  At the tip of the first groove 1a, an optical path changing mirror 15 for bending the optical path by 90 degrees is formed at a position directly below the light emitting element 12a.

  As shown in FIG. 3B, an internal waveguide 16 that is optically coupled to the light emitting element 12a of the first substrate 1 is provided in the first groove 1a of the first substrate 1. The internal waveguide 16 extends from the mirror portion 15 in the direction of the second groove 1b and is flush with the rear end portion 1d of the first groove 1a.

  The internal waveguide 16 includes a core portion 17 having a substantially square cross section with a high refractive index through which light propagates, and a cladding portion 18 having a refractive index lower than that. As shown in FIG. 2C, the left and right surfaces of the core portion 17 are covered with the cladding portion 18.

  As shown in FIG. 4A, a light emitting element 12a is mounted at a predetermined position on the surface of the first substrate 1 on which the internal waveguide 16 is provided, and the space between the light emitting element 12a and the core portion 17 is mounted. As shown in FIG. 2A, the optical transparent resin 13 is filled.

  Returning to FIG. 1, the first substrate 3 on the light receiving side will be described. The basic structure of the first substrate 3 on the light receiving side is the same as that of the first substrate 1 on the light emitting side. However, on the surface (upper surface) of the first substrate 3 on the light receiving side, a light receiving element 12b for converting an optical signal into an electric signal is flip-chip mounted with bumps with the light receiving surface facing downward. In addition, on the surface of the second substrate 6, an IC substrate (signal processing unit) 4b on which an IC circuit for transmitting an electric signal to the light receiving element 12b is formed is mounted. Different from 1. As this light receiving element 12b, PD (Photo Diode) is adopted, and the IC substrate 4b is an element such as a TIA (Trans-impedance Amplifier) that performs current / voltage conversion.

  The first substrate 1 on the light emitting side, the first substrate 3 on the light receiving side, and the IC substrates 4 a and 4 b are shielded by a shield case 8 attached to the surface of the second substrate 6, respectively. The through hole 8a is penetrated.

  Next, the optical fiber 2 will be described. As shown in FIGS. 1 and 5, the optical fiber 2 includes a core portion 17 of the internal waveguide 16 of the first substrate 1 on the light emitting side and a core portion 17 of the internal waveguide 16 of the first substrate 3 on the light receiving side. An optically connectable fiber core portion 21 is provided inside. And it is a cord type comprised by the fiber cladding part 22 surrounding the outer periphery of this fiber core part 21, and the coating | coated part 23 which coat | covers the outer periphery of this fiber cladding part 22. FIG. The fiber core portion 21, the fiber clad portion 22, and the covering portion 23 are circular.

  As shown in FIG. 1, the optical fiber 2 penetrates the through hole 8a of the shield case 8 and the covering portion 23 is peeled off in the vicinity of the second groove 1b of the first substrate 1 so that the fiber clad portion 22 is exposed. Yes.

  Then, as shown in FIGS. 2A, 2C, and 4B, the fiber clad portion 22 of the optical fiber 2 is installed in the second groove 1b of the first substrate 1, and the boundary portion with the first groove 1a. The fiber clad portion 22 is positioned at the rising slope portion. At this time, it is optically coupled with the optical axis of the core part 17 of the internal waveguide 16 of the first substrate 1 and the fiber core part 21 of the optical fiber 2 being aligned.

The gap between the end surface of the core portion 17 of the internal waveguide 16 of the first substrate 1 and the end surface of the fiber core portion 21 of the optical fiber 2 is 200 μm or less . In general, the gap 0 where the optical coupling efficiency is 100% is preferable. However, in this configuration, the gap is 60 μm to 100 μm due to restrictions on the groove width of the first substrate 15 and the outer diameter size of the optical fiber clad portion 26. It becomes.

  At the position of the surface of the first substrate 1, as shown in FIGS. 2A and 5, a holding block 24 is disposed on the upper portion of the fiber cladding portion 22 of the optical fiber 2, and the holding block 24 and the second groove 1 b are arranged. The space between is filled with the adhesive 14.

  As described above, the front end side of the fiber clad portion 22 of the optical fiber 2 is bonded and fixed to the first substrate 1 together with the pressing block 24 with the adhesive 14 while being pressed against the second groove 1 b by the pressing block 24. become.

  6 and 7 show a multi-channel optical module in which a plurality of core portions 17 (A, B) according to the present invention are arranged in one first groove 1a. FIG. 7B is a plan view of the core portion 17 (A, B) and the clad portion 18. In order to make the range of the clad portion 18 easy to understand, the clad portion 18 is hatched. The same applies to FIG. 11B described later.

  A plurality (two in this example) of core portions 17 (A, B) are arranged in parallel in a substantially trapezoidal first groove 1 a on the surface of the first substrate 1. The 1st groove | channel 1a is formed in the horizontal width W which can arrange | position the several core part 17 (A, B) with the fixed pitch P. As shown in FIG.

  Moreover, the mirror part 15 is formed corresponding to each core part 17 (A, B). Similarly, the light emitting element 12a is mounted corresponding to each mirror portion 15. Specifically, a holder 11 for holding two light emitting elements 12a corresponding to each mirror portion 15 is provided, and a circuit of each light emitting element 12a of the holder 11 is formed by a bump 12c with a metal circuit (patterning by copper or gold sputtering). Circuit) 10 is flip-chip mounted.

  And in the 1st groove | channel 1a of the vicinity of the adjacent mirror part 15, the scattering part (refer arrow a of FIG. 7A) of the reflected light of the mirror part 15 does not correspond, or the core part 17 (A) or The shielding part 30 which shields so that it may not leak to 17 (B) is formed.

  This shielding part 30 does not form the first groove 1a in the vicinity of the adjacent mirror part 15 and leaves the first substrate 1, that is, the first substrate 1 is partially utilized to make the first This is a shield 30 that is raised upward from the bottom of the groove 1a.

  Then, the clad portion 18 is formed by filling the clad of the internal waveguide 16 into the first groove 1a.

  The optical module as described above is a multi-channel optical module in which a plurality of core portions 17 (A, B) are arranged in one first groove 1a. Then, in the first groove 1a in the vicinity of the mirror unit 15, the shielding unit 30 shields the scattered component a of the reflected light of the mirror unit 15 from leaking to the non-corresponding core unit 17 (A) or 17 (B). Is formed.

  Therefore, the scattering component a of the reflected light from the mirror unit 15 is shielded by the shielding unit 30. That is, in the example of FIGS. 7A and 7B, the scattered component a of the reflected light of the mirror portion 15 of the core portion 17 (B) leaks (crosstalk) to the core portion 17 (A) which is an adjacent channel. It becomes difficult to do.

  As a result, it is possible to cope with an increase in the speed and capacity of data communication and an increase in the number of channels for supporting bidirectional communication. In addition, since the core portions 17 (A, B) can be narrowed by arranging a plurality of core portions 17 (A, B) in one first groove 1a, it contributes to miniaturization of the optical module. become able to. 6 and 7 (the same applies to the following drawings), the horizontal width of the shielding portion 30 is drawn wider than the horizontal width of the core portion 17 (A, B), but in reality, the core portion 17 (A , B) can be made narrower than the lateral width.

  If the shielding portion 30 is extended from the vicinity of the mirror portion 15 along the internal waveguide 16 and further in the direction of the optical fiber 2 (see arrow c in FIG. 7B), the core portion Leakage from the straight portion 17 (A, B) can also be suppressed.

  Furthermore, the shielding part 30 is formed by a part of the first substrate 1 left in the first groove 1a of the adjacent core parts 17 (A, B). If the first substrate 1 is a silicon substrate, the smooth and highly accurate mirror portion 15 and the first groove 1a having the raised shielding portion 30 can be simultaneously and easily formed by etching. .

  Incidentally, the optical module shown in FIG. 10 corresponding to FIG. 6 and FIG. 11 corresponding to FIG. 7 is the type without the shielding part 30 shown for comparison. According to this type, since the scattering component a of the reflected light of the mirror unit 15 is not shielded, in the example of FIGS. 11A and 11B, the scattered component a of the reflected light of the mirror unit 15 of the core unit 17 (B). However, it is understood that leakage (crosstalk) occurs in the core portion 17 (A) which is an adjacent channel.

  FIG. 8A shows an oxide film layer 34 formed on the surface of the raised shielding portion 30 of the first substrate 1 including the surface of the first groove 1a. The oxide film layer 34 is not limited to the surface of the shielding part 30 in the vicinity of the mirror part 15, and may be formed on the entire surface of the first substrate 1.

  According to this, since the oxide film layer 34 becomes a reflective layer, the leakage of the scattering component a can be further suppressed. Further, by making the refractive index of the core portion 17 (A, B) higher than the refractive index of the oxide film layer that is the shielding portion 30, the oxide film layer 34 can be used as the lower cladding.

  FIG. 8B shows a structure in which the removed portion 32 of the oxide film layer 34 is formed on the surface of the raised shielding portion 30 shown in FIG.

  According to this, when the leaked light d that multi-reflects the holder 11 (light emitting element 12a) and the clad portion 18 is generated, the leaked light d is absorbed from the removed portion 32 of the oxide film layer 34 into the first substrate 1. Can do.

  In FIG. 9, a light absorber 35 along the shielding portion 30 is disposed on the surface of the raised shielding portion 30 of the first substrate 1. As the light absorber 35, for example, there is an opaque acrylic or epoxy resin.

  According to this, when the leaked light d that multi-reflects the light emitting element 12 a and the clad portion 18 is generated, the leaked light d can be absorbed by the light absorber 35.

  In the above-described embodiment, a part of the first substrate 1 is used to form the shielding portion 30 that protrudes upward from the bottom of the first groove 1a. However, the present invention is not limited to this. For example, a shielding part in which another shielding sheet or the like is interposed between adjacent core parts 17 (A, B) may be used.

As described above, the optical module according to the present invention includes the internal waveguide provided in the groove formed on the surface of the substrate, the optical path conversion mirror formed at the tip of the groove, and the mirror. Mounted on the surface of the substrate so as to face the part, emits an optical signal to the core part of the internal waveguide via the mirror part, or receives an optical signal from the core part of the internal waveguide via the mirror part In an optical module including an optical element and an optical fiber having a fiber core portion optically coupled to a core portion of an internal waveguide, a plurality of the core portions are arranged in parallel in the groove, A plurality of core parts are formed in a width that can be arranged at a constant pitch, the mirror part is formed corresponding to each core part, the optical element is mounted corresponding to each mirror part, and the groove Inside is filled with cladding of internal waveguide Have been the core in the groove in the vicinity of the mirror portion, the scattering component of the reflected light of the mirror portion is shielded section for shielding so as not to be leaked to the core portion not corresponding is formed, the shielding portion, wherein the adjacent A part of the substrate left in the groove of the part is formed, and the substrate is a silicon substrate .

According to this, in a multi-channel optical module in which a plurality of core parts are arranged in one groove, the core part to which the reflected light scattering component of the mirror part does not correspond in the groove near the mirror part The shielding part which shields so that it may not leak is formed. Therefore, the shielding component makes it difficult for the scattered component of the reflected light from the mirror portion to leak (crosstalk) to the incompatible core portion, that is, the adjacent channel. As a result, it is possible to cope with an increase in the speed and capacity of data communication and an increase in the number of channels for supporting bidirectional communication. In addition, by arranging a plurality of core portions in one groove, the pitch of the core portions can be reduced, so that the optical module can be miniaturized.
In addition, the shielding part is formed by a part of the substrate left in the groove of the adjacent core part, and the substrate is a silicon substrate. Therefore, a smooth and high-precision mirror part and a raised shielding are obtained by etching. A groove having a portion can be formed simultaneously and easily.

  Moreover, the said shielding part can be set as the structure extended | stretched further in the direction of the optical fiber along the internal waveguide from the vicinity of the said mirror part.

  According to this, the leakage from the straight part of the core part can also be suppressed.

  In addition, an oxide film layer may be formed on the surface of the shielding portion including the surface of the groove.

  According to this, since the oxide film layer becomes the reflective layer, the leakage of the scattering component can be further suppressed. Further, by making the refractive index of the core portion higher than the refractive index of the oxide film layer, the oxide film layer can be a lower clad.

  Moreover, it can be set as the structure by which the removal part of the oxide film layer is formed in the surface of the said shielding part.

  According to this, in the case where leakage light that multi-reflects the optical element and the clad portion is generated, this leakage light can be absorbed by the substrate from the removed portion of the oxide film layer.

  Moreover, it can be set as the structure by which the light absorber along this shielding part is arrange | positioned on the surface of the said shielding part.

  According to this, in the case where leakage light that multi-reflects the optical element and the clad is generated, this leakage light can be absorbed by the light absorber.

DESCRIPTION OF SYMBOLS 1 1st board | substrate 1a 1st groove | channel 2 Optical fiber 12a Light emitting element (optical element)
15 Mirror part 16 Internal waveguide 17 (A, B) Core part 18 Clad part 21 Fiber core part 30 Shielding part 32 Removal part 34 Oxide film layer 35 Light absorber a, d Scattering component P Pitch W Horizontal width

Claims (5)

An internal waveguide provided in a groove formed on the surface of the substrate, an optical path conversion mirror formed at the tip of the groove, and mounted on the surface of the substrate so as to face the mirror, An optical element that emits an optical signal to the core part of the internal waveguide through the mirror part or receives an optical signal from the core part of the internal waveguide through the mirror part, and the optical part and the optical part of the internal waveguide In an optical module comprising an optical fiber having a fiber core portion coupled to
A plurality of the core parts are arranged in parallel in the groove, the groove is formed in a width that allows a plurality of core parts to be arranged at a constant pitch, and the mirror part corresponds to each core part. Formed, the optical element is mounted corresponding to each mirror portion, the groove is filled with a clad of an internal waveguide,
In the groove in the vicinity of the mirror part, a shielding part that shields the scattered component of the reflected light of the mirror part from leaking to the non-corresponding core part is provided ,
The optical module is characterized in that the shielding part is formed by a part of a substrate left in the groove of the adjacent core part, and the substrate is a silicon substrate .   2. The optical module according to claim 1, wherein the shielding portion is further extended in the direction of the optical fiber along the internal waveguide from the vicinity of the mirror portion. The optical module according to claim 1, wherein the surface of the shielding portion, wherein the oxide layer, including the surface of the groove is formed. The optical module according to claim 3 , wherein a removed portion of the oxide film layer is formed on the surface of the shielding portion.   The optical module according to claim 1, wherein a light absorber along the shielding portion is disposed on a surface of the shielding portion.

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