JP7178214B2 - Optical subassemblies and optical modules - Google Patents

Description

The present invention relates to optical subassemblies and optical modules.

An optical receiving subassembly (ROSA) is known that converts the optical path of externally incident light with a mirror and causes a light receiving element to receive the light (Patent Document 1). Also known is an optical transmission subassembly (TOSA) that converts the optical path of output light from a light emitting element with a mirror and emits it to the outside. Furthermore, a similar arrangement (BOSA) with transmit and receive functions is also known (US Pat. These are collectively called an optical subassembly (OSA). By using an optical component in which a mirror and a lens are integrated, the size of the device can be reduced (Patent Document 1). Optical elements and optical parts are housed in a housing (Patent Documents 3 to 6).

JP 2014-137410 A JP 2015-197651 A JP 2013-125045 A JP 2013-171161 A JP 2013-140292 A U.S. Patent Application Publication No. 2015/0253520

An optical component made of resin has a large coefficient of thermal expansion. As a result, the position of the mirror may fluctuate due to temperature rise, resulting in misalignment of the optical axis. Optical axis misalignment lowers the optical coupling efficiency, leading to performance degradation.

An object of the present invention is to suppress the occurrence of optical axis misalignment.

(1) An optical subassembly according to the present invention has an optical input/output section facing upward, and integrally includes a photoelectric element for converting at least one of an optical signal and an electrical signal to the other, and a mirror, and is made of resin. an optical component having the mirror above the photoelectric element; a bottom plate portion including a first region and a second region adjacent to each other; and a first wall portion rising from the bottom plate portion in the first region. a metal case to which the optoelectronic device and the optical component are fixed in the second region; an upper plate portion covering the case; a second wall facing the second region; a lid made of metal or resin; and an adhesive made of resin for bonding the case and the lid, wherein the adhesive A first adhesive between the mutually facing side end surfaces of the first wall portion and the second wall portion, and a second adhesive between the lower end surface of the second wall portion and the second region of the bottom plate portion. and an adhesive, wherein the first adhesive fixes the first wall portion and the second wall portion so as to resist upward and downward forces.

According to the present invention, even if the height of the mirror fluctuates due to the thermal expansion of the optical components, the thermal expansion of the second adhesive causes the bottom plate portion to tilt and the tilt angle of the mirror to change. can be suppressed.

(2) In the optical subassembly described in (1), a force due to thermal expansion of the second adhesive is applied from the second wall portion to the bottom plate portion, and the further away from the first adhesive, the force is applied to the bottom plate portion. and acting to widen the distance between the lower end surface of the second wall portion and the second region.

(3) The optical subassembly of (2), further comprising an optical interface fixed in position relative to the first region of the case, wherein the first region comprises the A position relative to an optical axis of light passing between the optical interface and the mirror is fixed, the optical component raises the position of the mirror due to thermal expansion, and the second region is the second adhesive. Due to the thermal expansion of the mirror, a side away from the first region is displaced downward, and the tilt of the mirror rises.

(4) In the optical subassembly described in any one of (1) to (3), the lid may have a larger coefficient of thermal expansion than the case.

(5) The optical subassembly according to any one of (1) to (4), wherein the adhesive adheres the upper end surface of the upper plate portion and the first wall portion. may be

(6) In the optical subassembly according to any one of (1) to (5), the first wall portion covers the first region except for a connection portion with the second region. It may be characterized in that the second wall portion has a shape surrounding the second region except for a connecting portion with the first region.

(7) The optical subassembly according to any one of (2) to (6), wherein the fixation portion of the optical component to the case extends in the direction between the optical interface and the mirror. It may be characterized by not adjoining the first wall but adjoining the second wall in an orthogonal direction.

(8) The optical subassembly according to any one of (1) to (7), further comprising an optical multiplexer/demultiplexer mounted in the first region so as to be optically coupled with the optical component. It may be characterized by

(9) The optical subassembly according to any one of (1) to (8), further comprising a base substrate firmly adhered to the bottom plate portion of the case in the second region, The photoelectric element and the optical component are fixed to the second region by fixing to the base substrate, the base substrate has a coefficient of thermal expansion equal to or greater than that of the bottom plate, and the bottom plate has a thermal expansion coefficient equal to or greater than that of the bottom plate. The expansion may be characterized by outward bending with the base substrate.

(10) The optical subassembly according to any one of (1) to (9), further comprising an electrical interface whose position relative to said second region of said case is fixed. It may be characterized by

(11) An optical module according to the present invention is the optical subassembly according to any one of (1) to (10), and outputs the electrical signal converted from the input optical signal. an optical subassembly comprising at least one of an optical receiving subassembly and an optical transmitting subassembly outputting the optical signal converted from the input electrical signal; and a circuit board electrically connected to the optical subassembly. , is characterized by having

1 is a perspective view of an optical module according to a first embodiment; FIG. 1 is a schematic diagram showing the configuration of an optical transmission device equipped with an optical module according to a first embodiment; FIG. 2 is a side view of the optical subassembly according to the first embodiment; FIG. 1 is an exploded perspective view of an optical subassembly according to a first embodiment; FIG. 1 is a schematic diagram of an optical subassembly according to a first embodiment; FIG. It is a figure which shows the expanded optical component which concerns on a reference example. Fig. 3 shows an expanded optical component according to the first embodiment; FIG. 5 is a schematic diagram of an optical subassembly according to Modification 1 of the first embodiment; FIG. 5 is a schematic diagram of an optical subassembly according to Modification 2 of the first embodiment; FIG. 5 is a perspective view showing optical components of an optical subassembly according to a second embodiment; FIG. 8 is an exploded perspective view of an optical subassembly according to a second embodiment;

BEST MODE FOR CARRYING OUT THE INVENTION Below, embodiments of the present invention will be described specifically and in detail based on the drawings. Members denoted by the same reference numerals in all drawings have the same or equivalent functions, and repeated description thereof will be omitted. Note that the size of the figure does not necessarily match the magnification.

[First embodiment]
FIG. 1 is a perspective view of an optical module according to the first embodiment. The optical module 100 is an optical receiver (optical transceiver) having a bit rate of 100 Gbit/s class and a transmission function and a reception function. Standard based. Optical module 100 includes housing 102 with pull tab 104 and slider 106 .

FIG. 2 is a schematic diagram showing the configuration of an optical transmission device equipped with the optical module 100 according to the first embodiment. A plurality of optical modules 100 are attached to the optical transmission device by electrical connectors 108, respectively. Optical transmission devices are, for example, large-capacity routers and switches. An optical transmission device has, for example, a switching function, and is installed in a base station or the like.

The optical transmission device acquires data for reception (electrical signal for reception) from the optical module 100, uses a driver IC (integrated circuit) 110 or the like to determine what data is to be transmitted to where. It generates credit data (electrical signal for transmission) and transmits the data to the corresponding optical module 100 .

The optical module 100 comprises a plurality of optical subassemblies 10 for converting at least one of optical and electrical signals to the other. The plurality of optical subassemblies 10 includes an optical transmitter optical subassembly (TOSA) having an optical transmission function, an optical receiver optical subassembly (ROSA) having an optical reception function, and a bidirectional subassembly having an optical transmission/reception function. assembly (BOSA: Bi-directional Optical Subassembly). An optical fiber 112 is connected to the optical subassembly 10 for the input and output of optical signals.

An electrical signal is transmitted to the circuit board 114 from the optical receiver subassembly 10A. Electrical signals are transmitted from the circuit board 114 to the optical transmission subassembly 10B. The circuit board 114 is a rigid board without flexibility.

3 is a side view of the optical subassembly according to the first embodiment; FIG. FIG. 4 is an exploded perspective view of the optical subassembly according to the first embodiment.

The optical subassembly 10 has a case 12 made of metal (kovar, stainless steel (SUS), CuW, etc.) having a thermal expansion coefficient of about 5×10 ⁻⁶ /K to 17×10 ⁻⁶ /K, for example. The case 12 has a bottom plate portion 14 including a first area A1 and a second area A2 adjacent to each other. The case 12 has a first wall portion 16 rising from the bottom plate portion 14 in the first area A1. The first wall portion 16 has a shape surrounding the first area A1 except for the connecting portion with the second area A2.

The optical subassembly 10 has a lid 18 made of metal or resin. The lid 18 has a coefficient of thermal expansion equal to or greater than that of the case 12 . The lid 18 has an upper plate portion 20 that covers the case 12 . The lid 18 has a second wall portion 22 that hangs down from the upper plate portion 20 next to the first wall portion 16 and faces the second area A2. The second wall portion 22 has a shape surrounding the second area A2 except for the connecting portion with the first area A1. A housing is configured by the case 12 and the lid 18 .

The optical subassembly 10 has an adhesive 24 made of resin. Adhesive 24 bonds case 12 and lid 18 together. The adhesive 24 bonds the upper end surface of the upper plate portion 20 and the first wall portion 16 . Adhesive 24 includes first adhesive 26 . A first adhesive 26 is between the mutually facing side end surfaces of the first wall 16 and the second wall 22 . Adhesive 24 includes a second adhesive 28 . The second adhesive 28 is between the lower end surface of the second wall portion 22 and the second area A2 of the bottom plate portion 14 . The first adhesive 26 fixes the first wall portion 16 and the second wall portion 22 against the upward and downward forces.

The optical interface 30 has a fixed position relative to the first area A1 of the case 12 . The optical interface 30 has a receptacle 32, a receptacle holder 34 and a lens holder 36 in which a collimating lens 38 (FIG. 5) is held.

The electrical interface 40 has a fixed position relative to the second area A2 of the case 12 . The electrical interface 40 is a printed circuit board (eg flexible board). For example, in the case of ROSA, an amplifier 42 such as a preamplifier and a chip capacitor 44 are fixedly mounted on the case 12 with an adhesive or the like. Note that description of wires for electrical connection is omitted.

FIG. 5 is a schematic diagram of an optical subassembly according to the first embodiment. The optical subassembly 10 has an optoelectronic device 46 for converting at least one of optical and electrical signals to the other. The optical subassembly 10 is an optical receiving subassembly that outputs an electrical signal converted from an input optical signal if the photoelectric element 46 is a light receiving element. Alternatively, if optoelectronic device 46 is a light emitting device, optical subassembly 10 is an optical transmission subassembly that outputs an optical signal converted from an input electrical signal. A plurality of optical input/output units 48 are monolithically integrated in the photoelectric element 46 so as to correspond to a plurality of channels. The photoelectric device 46 has a light input/output portion 48 facing upward. The photoelectric element 46 is fixed to the second area A2 of the case 12 .

The optical subassembly 10 has an optical component 50 . The optical component 50 has a lens 52 for narrowing down (for condensing) the optical signal to a desired beam diameter. The optical component 50 has a mirror 54 for redirecting the light at the point of reflection. Mirror 54 bends the optical path between lens 52 and mirror 54 by, for example, 90°. The optical component 50 integrally has a lens 52 and a mirror 54 . Optical component 50 has a pair of legs 56 . A pair of legs 56 are on opposite sides of the photoelectric element 46 . The lens 52 may be provided only on the side facing the photoelectric element 46, or may be provided on both sides of the light input/output.

The optical component 50 is fixed in the second area A2 so that the lens 52 is closer to the first area A1 than the mirror 54 is. Here, the entire lower portion of the optical component 50 is fixed as a fixing portion 66 . The optical component 50 is arranged such that the mirror 54 is positioned above the photoelectric element 46 . The fixed portion 66 of the optical component 50 is not adjacent to the first wall portion 16 but adjacent to the second wall portion 22 in a direction perpendicular to the direction between the lens 52 and the mirror 54 . The optical component 50 is made of resin (polyetherimide, acrylic, etc.) having a thermal expansion coefficient of about 5×10 ⁻⁵ /K, for example.

The optical multiplexer/demultiplexer 58 is mounted in the first area A1 so as to be optically coupled with the optical component 50 via the lens 52 . Here, the optical multiplexer/demultiplexer 58 is placed at a position where the height of the optical axis is adjusted by a pedestal 59 or the like. The pedestal 59 is fixed to the first area A1 by a fixing portion 67. As shown in FIG. Note that the optical multiplexer/demultiplexer 58 may be fixed directly without the pedestal 59 intervening. In the optical receiving subassembly, the optical multiplexer/demultiplexer 58 is an optical demultiplexer that demultiplexes wavelength-multiplexed optical signals into optical signals corresponding to respective channels. The first area A1 has a fixed position relative to the optical axis of light passing between the optical interface 30 and the lens 52 .

FIG. 6 is a diagram showing an expanded optical component 50 according to a reference example. Optical component 50 expands due to heat. The mirror 54 of the expanded optical component 50 rises from its original position P, thereby causing optical coupling degradation. The center of expansion at this time is the center position of the fixed portion 66 .

FIG. 7 is a diagram showing an expanded optical component 50 according to the first embodiment. As described above, the first adhesive 26 (FIG. 3) secures the first wall 16 and the second wall 22 against upward and downward forces. Also, the second adhesive 28 ( FIG. 3 ) is present between the lower end surface of the second wall portion 22 and the second area A<b>2 of the bottom plate portion 14 .

A force due to thermal expansion of the second adhesive 28 is applied from the second wall portion 22 to the bottom plate portion 14 . The force acts to widen the distance between the lower end surface of the second wall portion 22 and the second area A2 as the distance from the first adhesive 26 (or the first area A1) increases. Due to the thermal expansion of the second adhesive 28, the second area A2 is displaced downward on the side away from the first area A1, as shown in FIG. Alternatively, the bottom plate portion 14 bends. This raises the tilt of the mirror 54 .

According to this embodiment, even if the height of the mirror 54 fluctuates due to the thermal expansion of the optical component 50, the thermal expansion of the second adhesive 28 tilts the bottom plate portion 14 and changes the angle of reflection on the mirror 54. Occurrence of optical axis misalignment can be suppressed. More specifically, as shown in the reference example of FIG. 6, the reflected light from the mirror 54 and the light input/output unit 48 are shifted leftward in FIG. 6 due to thermal expansion. According to the present embodiment, since the bottom plate portion 14 is displaced in the downward direction as shown in FIG. 7, the angle of reflection at the mirror 54 changes, and the reflected light is directed to cancel out the leftward shift in FIG. It can be directed to the optical input/output unit 48 . This is due to the structure of the case 12 and the lid 18 and the arrangement position of the optical component 58 . By forming the lid 18 with a material having a larger coefficient of thermal expansion than the case 12, the displacement of the bottom plate portion 14 can be increased, and the effect of suppressing deterioration of optical coupling due to thermal expansion can be improved. Further, in the present embodiment, since the fixing portion 66 of the optical component 50 is arranged at a position surrounded by the second wall portion 22, the change in the angle of reflection on the mirror 54 caused by the deformation of the bottom plate portion 14 can be increased.

[Modification 1 of the first embodiment]
FIG. 8 is a schematic diagram of an optical subassembly according to Modification 1 of the first embodiment. This modification differs from the first embodiment in that the area of the fixing portion 166 of the optical component 150 does not extend over the entire optical component 150 and part of the optical component 150 is included in the first area A1. different. All the fixing portions 166 of the optical component 150 are included in the second area A2. Also in this modification, since the fixed portion 166 is included in the second region A2, the change in the reflection angle of the mirror 54 due to the deformation of the bottom plate portion 14 of the case 12 due to thermal expansion described in FIG. It is possible to suppress deterioration of optical coupling.

[Modification 2 of the first embodiment]
FIG. 9 is a schematic diagram of an optical subassembly according to Modification 2 of the first embodiment. This modification differs from the first embodiment in that part of the optical multiplexer/demultiplexer 58 is included in the second area A2. In this modified example as well, since the fixing portion 66 is included in the second region A2, the change in the reflection angle of the mirror 54 caused by the deformation of the bottom plate portion 14 of the case 12 due to thermal expansion described in FIG. It is possible to suppress deterioration of optical coupling.

As described above, if the fixing portions 66, 166 of the optical components 50, 150 are arranged only within the second area A2, the effects of the present invention can be obtained.

[Second embodiment]
FIG. 10 is a perspective view showing optical components of an optical subassembly according to the second embodiment. FIG. 11 is an exploded perspective view of the optical subassembly according to the second embodiment. In this embodiment, the base substrate 260 is firmly adhered to the bottom plate portion 214 of the case 212 in the second area A2. The optoelectronic device and optical component 250 are fixed in the second area A2 by being fixed to the base substrate 260 .

The base substrate 260 has a larger coefficient of thermal expansion than the bottom plate portion 214 . Therefore, since the base substrate 260 stretches well, the bottom plate portion 214 bends outward together with the base substrate 260 due to thermal expansion. Therefore, the effects described in the first embodiment can be promoted. Other contents correspond to the contents described in the first embodiment. However, even if the thermal expansion coefficients of the base substrate 260 and the case 12 are the same, the effects described in the first embodiment can be obtained.

The present invention is not limited to the above-described embodiments, and various modifications are possible. For example, the configurations described in the embodiments can be replaced with configurations that are substantially the same, configurations that produce the same effects, or configurations that can achieve the same purpose.

10 optical subassembly, 10A optical receiver subassembly, 10B optical transmitter subassembly, 12 case, 14 bottom plate, 16 first wall, 18 lid, 20 upper plate, 22 second wall, 24 adhesive, 26 second 1 adhesive, 28 second adhesive, 30 optical interface, 32 receptacle, 34 receptacle holder, 36 lens holder, 38 collimating lens, 40 electrical interface, 42 amplifier, 44 chip capacitor, 46 photoelectric element, 48 optical input/output Part 50 Optical Part 52 Lens 54 Mirror 56 Leg 58 Optical Multiplexer/Demultiplexer 59 Pedestal 66 Fixing Part 67 Fixing Part 100 Optical Module 102 Housing 104 Pull Tab 106 Slider 108 Electrical Connector 110 driver IC, 112 optical fiber, 114 circuit board, 150 optical component, 166 fixing portion, 212 case, 214 bottom plate portion, 250 optical component, 260 base substrate, A1 first area, A2 second area, P position.

Claims (9)

a photoelectric element with an optical input/output portion facing upward, for converting at least one of an optical signal and an electrical signal to the other;
an optical component integrally having a mirror and made of resin, the optical component having the mirror above the photoelectric element;
a bottom plate portion including a first region and a second region adjacent to each other; and a first wall portion rising from the bottom plate portion in the first region, wherein the photoelectric element and the optical component are located in the second region. a fixed, metallic case;
a lid made of metal or resin, having an upper plate portion that covers the case, and a second wall portion that hangs from the upper plate portion adjacent to the first wall portion and faces the second region;
an adhesive made of a resin that bonds the case and the lid;
an optical interface having a fixed position relative to the first region of the case;
has
The adhesive includes a first adhesive between the mutually facing side end surfaces of the first wall portion and the second wall portion, a lower end surface of the second wall portion and the second region of the bottom plate portion. and a second adhesive between
The first adhesive fixes the first wall portion and the second wall portion so as to resist the force of vertical displacement,
A force due to thermal expansion of the second adhesive is applied from the second wall portion to the bottom plate portion, and the distance between the lower end surface of the second wall portion and the second region increases as the distance from the first adhesive increases. acts to widen the
the first region has a fixed position relative to an optical axis of light passing between the optical interface and the mirror;
The position of the mirror rises due to thermal expansion of the optical component,
The optical subassembly, wherein the thermal expansion of the second adhesive displaces the second region downward on a side away from the first region, causing the tilt of the mirror to rise. An optical subassembly according to claim 1 , comprising:
The optical subassembly, wherein the lid has a larger coefficient of thermal expansion than the case. An optical subassembly according to claim 1 or 2 ,
The optical subassembly, wherein the adhesive adheres the top surface of the upper plate portion and the first wall portion. An optical subassembly according to any one of claims 1 to 3 ,
The first wall has a shape surrounding the first region except for a connection portion with the second region,
The optical subassembly, wherein the second wall portion has a shape surrounding the second region except for a connection portion with the first region. An optical subassembly according to any one of claims 1 to 4 ,
A fixing portion of the optical component to the case is characterized in that it is not adjacent to the first wall portion but adjacent to the second wall portion in a direction orthogonal to a direction between the optical interface and the mirror. and optical subassemblies. An optical subassembly according to any one of claims 1 to 5 ,
An optical subassembly, further comprising an optical multiplexer/demultiplexer mounted in said first region for optical coupling with said optical component. An optical subassembly according to any one of claims 1 to 6 ,
further comprising a base substrate bonded to the bottom plate portion of the case in the second region;
the photoelectric element and the optical component are fixed to the second region by fixing to the base substrate;
the base substrate has a coefficient of thermal expansion equal to or greater than that of the bottom plate;
The optical subassembly, wherein the bottom plate portion bends outward together with the base substrate due to thermal expansion. An optical subassembly according to any one of claims 1 to 7 ,
An optical subassembly further comprising an electrical interface having a fixed position relative to said second region of said case. 9. An optical subassembly according to any one of claims 1 to 8 , wherein an optical receiving subassembly for outputting said electrical signal converted from said input optical signal and converting from said input electrical signal. at least one optical subassembly of optical transmission subassemblies for outputting the optical signal;
a circuit board electrically connected to the optical subassembly;
An optical module characterized by comprising:

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