阅读说明：本技术 光模块 (Optical module ) 是由 原弘 于 2020-01-22 设计创作，主要内容包括：一个实施方式所涉及的光模块具有：基板,其具有平面状的安装面；光回路元件,其具有对光进行传输的光波导、及将经过光波导的光作为平行光而射出的反射面；以及受光元件,其安装于安装面上,具有对从反射面射出的光进行聚光的透镜、及对由透镜聚光后的光进行受光的受光层。光相对于透镜的顶点的切平面而垂直地射入。射出光的光回路元件的反射面和透镜的顶点之间的距离设定为比规定值短。在从安装面的法线方向观察时,光的光轴和透镜的顶点之间的距离被设定为规定的偏移量。(An optical module according to an embodiment includes: a substrate having a planar mounting surface; an optical circuit element having an optical waveguide for transmitting light and a reflecting surface for emitting the light passing through the optical waveguide as parallel light; and a light receiving element mounted on the mounting surface and having a lens for collecting light emitted from the reflecting surface and a light receiving layer for receiving the light collected by the lens. Light is incident perpendicularly with respect to the tangent plane of the apex of the lens. The distance between the reflecting surface of the light return element from which the light is emitted and the vertex of the lens is set to be shorter than a predetermined value. The distance between the optical axis of the light and the vertex of the lens is set to a predetermined offset amount when viewed from the normal direction of the mounting surface.)

1. An optical module, comprising:

a substrate having a planar mounting surface;

an optical circuit element having an optical waveguide for transmitting an optical signal in a transmission direction parallel to the mounting surface, and a reflection surface for reflecting the optical signal transmitted in the optical waveguide and emitting the optical signal as a light beam toward the substrate;

a support member that supports the optical circuit element above the mounting surface; and

a light receiving element that is provided on the mounting surface and has a condensing lens that condenses the light beam on an upper surface of the light receiving layer and a light receiving layer that is parallel to the mounting surface,

the light flux emitted from the reflecting surface enters the condenser lens in a direction perpendicular to a tangential plane to a vertex of the condenser lens,

the light beam travels along an optical path from the reflection surface to the tangent plane, the optical path having a minimum distance set shorter than a prescribed value,

the light flux has an optical axis that is offset from a vertex of the condenser lens by a predetermined offset amount when viewed from a direction perpendicular to the mounting surface.

2. The light module of claim 1,

the height of the support member coincides with the distance between the mounting surface and the optical circuit element,

adjusting the minimum distance by changing a height of the support member.

3. The light module according to claim 1 or 2,

the offset is set to a distance longer than a beam diameter of the light beam.

4. The light module according to any one of claims 1 to 3,

the minimum distance is set shorter than a rayleigh length of the light beam.

5. The light module according to any one of claims 1 to 4,

the light beam is collimated light.

6. The light module according to any one of claims 1 to 5,

the reflecting surface is a reflecting surface that forms an angle of 45 ° with respect to the mounting surface and reflects the optical signal toward the mounting surface.

7. The light module according to any one of claims 1 to 6,

the offset amount is shorter than a difference distance between the radius of the condenser lens and the radius of the light beam.

8. The light module according to any one of claims 1 to 7,

the light receiving device further includes a support member provided on the mounting surface, and the light receiving element is provided on the support member.

9. The light module according to any one of claims 1 to 8,

when viewed from a direction perpendicular to the mounting surface, a center point of the light-receiving layer coincides with a center point of the condenser lens.

10. The light module according to any one of claims 1 to 9,

the support member is a parallelepiped.

Technical Field

One aspect of the present invention relates to an optical module.

Background

Japanese patent application laid-open No. 2017-32731 describes a wavelength multiplexing optical receiving module. The wavelength-division multiplexing optical receiving module divides wavelength-division multiplexing light including a plurality of signal lights having different wavelengths into a single signal light and reproduces signals included in the respective signal lights. The wavelength multiplexing optical receiving module includes: an optical receptacle connected with an external optical fiber; and a package that houses the light receiving element. The optical splitter and the mirror are housed inside the package. The optical splitter splits wavelength-multiplexed light emitted from a collimator lens disposed inside the optical receptacle into a plurality of signal lights having different wavelengths from each other. The reflecting mirror reflects the branched signal light. A lens array that condenses light reflected by the mirror and a PD (Photo Diode) that receives light condensed by the lens array are disposed inside the package. The PD has: a single lens for receiving light from the lens array; a light receiving layer for receiving light transmitted through the single lens; and a reflective layer located at a lower portion of the light receiving layer.

Disclosure of Invention

An optical module according to an aspect of the present invention includes: a substrate having a planar mounting surface; an optical circuit element having an optical waveguide for transmitting light and a reflecting surface for emitting the light passing through the optical waveguide as parallel light; a support member that supports the optical circuit element on the mounting surface; and a light receiving element mounted on the mounting surface and having a lens for collecting light emitted from the reflecting surface and a light receiving layer for receiving the light collected by the lens. Parallel light is incident perpendicularly with respect to the tangential plane at the apex of the lens. The distance between the reflecting surface of the light return element that emits the parallel light and the vertex of the lens is set to be shorter than a predetermined value. The distance between the optical axis of the parallel light and the vertex of the lens is set to a predetermined offset amount when viewed from the normal direction of the mounting surface.

Drawings

Fig. 1 is a perspective view showing an optical module according to an embodiment of the present invention.

Fig. 2 is a side view of the light module of fig. 1.

Fig. 3 is a diagram showing an optical circuit element of the optical module of fig. 1.

Fig. 4 is an enlarged side view of the substrate, the light receiving element, and the optical circuit element of the optical module of fig. 1.

Fig. 5 is an enlarged side view of the light receiving element of fig. 4 with a lens.

Fig. 6 is a plan view showing a lens of the light receiving element of fig. 4 and a light flux from the optical circuit element.

Fig. 7 is a diagram schematically showing light emitted from the optical circuit element of fig. 3.

Fig. 8 is a side view showing a light receiving element and an optical circuit element of an optical module of a comparative example.

Fig. 9 is a side view showing a light receiving element and an optical circuit element of an optical module of a comparative example different from fig. 8.

Detailed Description

[ detailed description of the embodiments ]

Next, a specific example of the optical module according to the embodiment will be described with reference to the drawings. The present invention is not limited to the following examples, but is defined by the claims and encompasses all modifications within the scope equivalent to the claims. In the description of the drawings, the same or corresponding elements are denoted by the same reference numerals, and overlapping description is omitted as appropriate. In the drawings, parts may be simplified or exaggerated for the purpose of facilitating understanding, and the dimensional ratios and angles are not limited to those described in the drawings.

Fig. 1 is a perspective view showing an optical module 1 according to an embodiment, fig. 2 is a side view showing the optical module 1, as shown in fig. 1 and 2, the optical module 1 includes a substrate 2 on which a circuit for processing an electric signal is mounted and which has a planar mounting surface 2b, a support member 3 mounted on the mounting surface 2b, an optical circuit element 4 for demultiplexing a multiplexed optical signal, and a plurality of light receiving elements 5 for receiving lights L demultiplexed by the optical circuit element 4, the light receiving elements 5 are, for example, PD (Photo Diode) photodiodes, the substrate 2 may be mounted with a circuit for transmitting an optical signal and a light emitting element (not shown) for receiving an incident light L0 multiplexed from an optical fiber, and the optical circuit element 4 demultiplexes the multiplexed incident light L0 into the respective lights L, the optical module 1 may be mounted with a circuit for transmitting an optical signal and a light emitting element (not shown), the optical module 1 may be mounted with a circuit for transmitting and receiving an optical signal and the optical transceiver, the optical transceiver 5 may be mounted on the mounting surface 2b of the substrate 2b, and the optical module 1 may be referred to the direction of the substrate 2, and the direction of which is referred to the direction of the TIA 2, and the direction of the TIA 2 is referred to the TIA 7, and the direction of the TIA 2, which is referred to the direction of the TIA 7, and the direction of the TIA 7, which is referred to the TIA 7, and the TIA 7, which is referred to the TIA 7.

Fig. 3 is a bottom view of the optical circuit element 4 as viewed from below, the optical circuit element 4 illustrated in fig. 3 includes an Arrayed Waveguide type diffraction Grating element (AWG), the optical circuit element 4 includes, for example, an optical Waveguide for transmitting light from an optical fiber, and in the optical circuit element 4, as the optical Waveguide, there are formed an input Waveguide 4b to which wavelength multiplexing light of 4 wavelengths is input, an input-side plate Waveguide 4c, an Arrayed Waveguide 4d, an output-side plate Waveguide 4f, and 4 output waveguides 4g, the input Waveguide 4b, the input-side plate Waveguide 4c, the Arrayed Waveguide 4d, the output-side plate Waveguide 4f, and the output Waveguide 4g are formed on a lower surface 4h of the optical circuit element 4 opposite to the mounting surface 2b, incident light L0 input from the optical fiber to the input Waveguide 4b, the incident light L input to the Arrayed Waveguide 4d via the input-side plate Waveguide 4c is split into light L, L, 36, 23, 73723, and 7374 g, and the light waves input to the Arrayed Waveguide 4b are split into light L, 364 f, the respective optical circuit elements, and output light beams 19, 35, and the output waveguides 3, 6854 f, and the external optical circuit element 4f, and the output waveguides 3, the optical circuit element 4g, the optical circuit element 4f, the optical circuit element 4b, the Waveguide 3, the optical circuit element 4f, the optical circuit element 4b, the Waveguide 3.

Fig. 4 is a side view showing an emitting portion of light L of the optical circuit element 4, the substrate 2, the light receiving element 5, the PD holder 6, the TIA 7, and the lead wire 8, for example, as shown in fig. 4, a reflection surface 4j is formed at an end portion of the optical circuit element 4, the reflection surface 4j is set to be a cut surface of a tapered surface (taper) forming an angle of 45 ° with respect to the vertical direction when the lower surface 4h of the optical circuit element 4 is 90 ° with respect to the vertical direction, and the traveling direction of the light L transmitted through the optical waveguide formed on the lower surface 4h is bent by 90 ° with respect to the vertical direction, that is, the reflection surface 4j reflects light L transmitted along the lower surface 4h of the optical circuit element 4 downward, the reflection surface 4j emits light L passing through each output waveguide 4g of the optical circuit element 4 as parallel light, the light emitted from the reflection surface 4j to the light receiving element 5, the support member 3 is formed in a shape of, for example, the support member 3 has an upper surface 3a contact with the optical circuit element 4h, and a lower surface 3b, which is capable of emitting light from the optical axis direction of being parallel to the lower surface of the optical circuit element 4h, and a lower surface of being formed so as to be capable of emitting from the substrate 3b, and a direction of emitting surface of being parallel to be capable of emitting from the substrate 3b, and a support member 3.

The light receiving element 5 is mounted on the mounting surface 2b of the substrate 2 via the PD holder 6, the light receiving element 5 includes a lens 5b that condenses the parallel light L emitted from the reflection surface 4j of the optical circuit element 4, and a light receiving layer 5c that receives the light L condensed by the lens 5b, the light receiving layer 5c is, for example, a circular plate, the lens 5b is, for example, a convex lens projecting toward the optical circuit element 4 side, and has a curved surface (a spherical surface as an example) opposing the reflection surface 4j in the upper and lower direction, 387 the light entering the lens 5b is condensed at the lens 5b, the light L condensed by the lens 5b enters the light receiving layer 5c, the light L entering the light receiving layer 5c is converted into an electric signal (photocurrent) and transmitted to the TIA 7 via the wire 8, the light L from the reflection surface 4j enters perpendicularly to the incident position of the lens 5b with respect to the tangent plane S of the vertex 5d, the light L is separated from the vertex 5d of the lens 5b by a predetermined amount of shift, i.e.g., the light shift amount in the optical axis X8678 direction when the incident position is observed from the vertex 5 d.

In the optical module 101 of the comparative example, as shown in fig. 8, light L from the reflection surface 104j of the optical circuit element 104 enters perpendicularly to the tangent plane S of the vertex 105d of the light receiving element 105 and enters the vertex 105d toward the light L of the lens 105b, and the light L enters the lens at different positions in the optical module 101 and the optical module 1, and the same is true in other respects, in the case of the optical module 101, the lens 105b has a spherical shape and the light L enters perpendicularly to the vertex 105d, that is, the tangent plane S becomes a lens surface perpendicular to the light L, the light L entering perpendicularly to the lens 105b is reflected by 180 ° at the lens 105b (the vertex 105d), and thus there is a possibility of a return light to the optical circuit element 104, and in the optical module 101, as described above, the light L becomes a return light to the optical circuit element 104, and there is a possibility of a problem that an OR L (optical return loss L) increases.

As a countermeasure against the above problem, for example, as shown in fig. 9, it is conceivable to use an optical circuit element 204 having a reflection surface 204j inclined at an angle other than 45 ° (40 ° as an example) with respect to the mounting surface 2b instead of the optical circuit element 104, thereby changing the emission direction of the light L toward the lens 105b so as to incline the optical axis X from the vertical direction, in which case the light L does not enter perpendicularly to the tangent plane of the vertex 105d of the light receiving element 105, but even when the emission direction of the light L is changed as described above, there is still a tangent plane in which the emission direction of the light L is equal to the normal direction on the curved surface of the lens 105b, and therefore there is a possibility that the light L of this component will be returned to the optical circuit element 204, and therefore, even when the emission direction of the light L is changed using the optical circuit element 204, there is still a possibility that the problem of increase in OR L arises.

Therefore, in the present embodiment, OR L is reduced by a method different from that of fig. 9, fig. 5 is a side view showing the light L, the lens 5b of the light receiving element 5, and the light receiving layer 5c according to the present embodiment, fig. 6 is a plan view schematically showing the light L and the lens 5b viewed from the normal direction of the mounting surface 2b in the present embodiment, and fig. 5 and 6 show that the light L is emitted from the reflecting surface 4j to the lens 5b as parallel light having a constant beam diameter R, the distance D in the vertical direction between the reflecting surface 4j and the vertex 5D of the lens 5b is set shorter than a predetermined value, for example, a rayleigh length described later, as shown in the above, the light L as parallel light is incident on the lens 5b perpendicularly to the tangent plane S of the vertex 5D, and the light L is incident on the portion of the lens 5b other than the vertex 5D, and therefore, in the range on the curved surface of the lens 5b, the light L is not incident, and the light is not emitted in the direction of the optical axis L, and thus, the light path is not shifted from the tangent direction of the lens 5b, and is not shifted from the optical axis X5D, and thus, and the optical axis X is not changed appropriately as long as a circle, the optical axis of the optical axis X-ray path of the optical axis of the lens 5b, and.

As an example, the aperture a1 of the lens 5b is 100 μm, the radius of curvature a2 of the lens 5b is 70 μm, for example, the beam diameter R of the light L is 10 μm, the offset amount F of the optical axis X from the vertex 5d of the lens 5b is 10 μm or more, and when the offset amount F is 10 μm, the incident angle of the light L with respect to the lens 5b is 4.0 ° or more and 12.6 ° or less, and therefore, the return of the light L to the optical circuit element 4 is suppressed, and from the viewpoint of the incidence of the light L to the lens 5b, the upper limit of the offset amount F may be 45 μm, the chip thickness A3 of the light receiving element 5 is 150 μm, and the diameter a4 of the light receiving layer 5c of the light receiving element 5 is 15 μm.

Fig. 7 is a side view schematically showing light L emitted from the reflection surface 4j, light L as parallel light is emitted from the reflection surface 4j as described above, light L forms a beam waist W in the vicinity of the emission portion of the reflection surface 4j, and travels in front and rear thereof as plane waves (collimated light) of a beam diameter R, and if light L is separated from the emission portion of the reflection surface 4j to be longer than the rayleigh length, light L is gently diverged, in the present embodiment, the length of light L in the direction of the optical axis X of light L as a plane wave is set to the rayleigh length which is proportional to the square of the radius of the beam waist W, the radius of the beam waist W is smaller than the beam diameter, but the radius of the beam waist W may be set to R as an approximation, and the distance between the reflection surface 4j and the lens 5b is set to be shorter than the rayleigh length, whereby light L can be incident on the lens 5b in a state of traveling with the beam diameter R.

In this embodiment, an experiment was performed to estimate the rayleigh length using a surface-incident type PD (photo diode) having a light receiving diameter of 50 μm of the light receiving layer 11, in which the light receiving sensitivity of the PD was obtained by first setting the optical axis X of the light L of the light receiving layer 11 and the optical circuit element 4 at the center of the light receiving diameter of the light receiving layer 11 and changing the distance from the optical circuit element 4 of the light receiving layer 11, and as a result, the light receiving sensitivity of the PD started to decrease when the distance Y between the optical circuit element 4 and the light receiving layer 11 was greater than or equal to 75 μm, and therefore, 75 μm was estimated to be a value longer than the rayleigh length, whereas the light receiving sensitivity of the PD did not decrease when the distance Y between the optical circuit element 4 and the light receiving layer 11 was less than or equal to 50 μm, and therefore, 50 μm was considered to be a value shorter than the rayleigh length.

Through the above experiment, as shown in fig. 4, the distance D between the reflecting surface 4j of the optical circuit element 4 that emits the light L and the apex 5D of the lens 5b is preferably shorter than 50 μm, which is the rayleigh length of the present embodiment, that is, the distance between the exit position of the light L from the optical circuit element 4 and the lens 5b of the light receiving element 5 is shorter than the distance that detects the spread of the light L emitted as parallel light, for example, less than or equal to 50 μm, the distance D can be appropriately changed by, for example, adjusting the height H of the support member 3 mounted on the mounting surface 2b, and the height H of the support member 3 is equal to the distance between the upper surface 3a and the lower surface 3 b.

Next, the operation and effect obtained by the optical module 1 according to the present embodiment will be described in detail, in the optical module 1, the optical circuit element 4 is supported on the planar mounting surface 2b of the substrate 2 via the supporting member 3, the optical circuit element 4 has an input waveguide 4b which is an optical waveguide through which the incident light L0 propagates, an input-side slab waveguide 4c, an array waveguide 4D, an output-side slab waveguide 4f, an output waveguide 4g, and a reflection surface 4j which reflects the light L passing through the output waveguide 4g, and light L which is parallel light is emitted from the reflection surface 4j, and light L emitted from the reflection surface 4j is incident on the lens 5b, and a distance D between the reflection surface 4j and a vertex 5D of the lens 5b is set to be shorter than a predetermined value, and if parallel light which is transmitted to a distant place is extended, there is a possibility that loss of light is generated, and if parallel light which is incident on the lens 5b is extended, there is a possibility that the loss of light from the reflection surface 4j of the light emitting the light L and the reflection surface 5b is increased by a predetermined value, and thus the possibility that the reflection loss of light from the reflection surface 5b is increased, and the reflection surface L is set to be increased.

In the optical module 1, the light L from the reflecting surface 4j enters perpendicularly to the tangential plane S of the vertex 5d of the lens 5b, and the distance between the position of the vertex 5d of the lens 5b and the optical axis X of the light L when viewed from the normal direction (i.e., the vertical direction) of the attachment surface 2b is set to a predetermined offset amount f.

The predetermined value may be determined by the height H of the support member 3. In this case, the distance D between the reflecting surface 4j and the vertex 5D of the lens 5b is determined by the height H of the supporting member 3 interposed between the substrate 2 and the optical circuit element 4. Therefore, by placing the support member 3 with the adjusted height H on the substrate 2, the distance D between the reflecting surface 4j and the vertex 5D of the lens 5b can be determined. This makes it possible to easily and accurately set the distance D between the reflecting surface 4j and the vertex 5D of the lens 5 b.

The shift amount F may also be greater than OR equal to the beam diameter R of the light L in which case the shift amount F of the optical axis X of the light L from the vertex 5d of the lens 5b is greater than OR equal to the beam diameter R, so the light L can be reliably prevented from entering the vertex 5d of the lens 5b, and therefore the light L can be prevented from entering the vertex 5d of the lens 5b, so the OR L can be more effectively reduced.

In this case, the distance D between the reflecting surface 4j and the apex 5D of the lens 5b is shorter than the rayleigh length, and therefore the light L can be made incident on the lens 5b before the light L from the reflecting surface 4j expands, and therefore the generation of the vertically incident light on the curved surface of the lens 5b can be more reliably suppressed, and therefore the OR L can be more effectively reduced.

The embodiments of the optical module according to the present invention have been described above. However, the present invention is not limited to the above-described embodiments. That is, the present invention can be variously modified and changed within the scope of the gist of the present invention described in the claims, and it is easily understood by those skilled in the art. For example, in the above-described embodiment, an example in which the reflecting surface 4j is provided at the end of the optical circuit element 4 is described. However, the position of the reflecting surface can be changed as appropriate. In the above-described embodiment, the optical circuit element 4 as the AWG is described. However, the type of the optical circuit element can be changed as appropriate.

In the above-described embodiment, an example in which 4 light receiving elements 5 are mounted on the mounting surface 2b of the substrate 2 via the PD holder 6, the TIA 7 is mounted on the mounting surface 2b of the substrate 2, and the optical circuit element 4 is mounted on the mounting surface 2b of the substrate 2 via the support member 3 has been described. However, the mounting method of the support member, the optical circuit element, and the light receiving element mounted on the mounting surface 2b of the substrate 2 can be changed as appropriate. In the above-described embodiment, the optical module 1 as an optical receiver is described. However, the present invention can also be applied to an optical module other than an optical receiver, such as an optical transmitter.