JP2016018146A - Optical module and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical module having thin thickness capable of easily adjusting an optical axis and a method for manufacturing the optical module.SOLUTION: An optical module 10 includes: a planar optical waveguide circuit 22 arranged on a substrate 21; a groove 107 arranged on the surface being opposite side from the surface on which the planar optical waveguide circuit 22 of the substrate 21 is arranged; and an optical device 105 arranged in the grieve 107 for making light incident to the planar optical waveguide circuit 22, and for receiving light outgoing from the planar optical waveguide circuit 22.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an optical module in which optical elements are integrated and mounted at high density and a method for manufacturing the same.

  As an optical module in which a planar lightwave circuit (PLC) and a plurality of optical devices are integrated, for example, optical modules shown in Patent Document 1 and Patent Document 2 can be cited. Patent Document 1 discloses an optical module in which an optical device is disposed on a PLC disposed on a substrate. Patent Document 2 shows an optical module in which an optical device is arranged at an end of a PLC. When an optical device is arranged on a layer constituting the PLC, the optical device is guided in the optical waveguide of the PLC, and the optical path of the optical signal emitted from the optical waveguide is directed toward the optical device arranged on the PLC. Convert. Specifically, the light guided inside the PLC and the optical device are optically coupled using a micromirror.

  FIG. 1A shows an example of an optical module in which an optical device 105 and an electronic device 106 are arranged on a PLC 22. The optical module in FIG. 1A includes a mirror structure 104, a PLC 22, a substrate 21, an optical device 105, and an electronic device 106. Reference numeral 108 denotes a bonding wire. The bonding wire 108 electrically connects the optical device 105 and the electronic device 106. In the optical module of FIG. 1A, the PLC 22 is formed on the substrate 21, and the optical device 105 and the electronic device 106 are disposed on the PLC 22. Tp1 is the thickness of the optical device 105 or the electronic device 106, Tw1 is the thickness of the PLC 22, and Tsub1 is the thickness of the substrate 21.

  FIG. 1B shows an example of an optical module in which the optical device 105 and the electronic device 106 are arranged on the substrate 21. The optical module in FIG. 1B includes a mirror structure 104, a PLC 22, a substrate 21, a support substrate 23, an optical device 105, and an electronic device 106. Reference numeral 108 denotes a bonding wire. The bonding wire 108 electrically connects the optical device 105 and the electronic device 106. In the optical module of FIG. 1B, after the PLC 22 is formed on the substrate 21, the optical device 105 and the electronic device 106 are arranged on the substrate 21 with the PLC 22 as the lower surface side. Tp2 is the thickness of the optical device 105 or the electronic device 106, Tw2 is the thickness of the PLC 22, Tsub2 is the thickness of the substrate 21, and Tsup2 is the thickness of the support substrate 23.

  The total thickness of the optical module shown in FIG. 1A is the sum of Tp1, Tw1, and Tsub1, and the total thickness of the optical module shown in FIG. 1B is Tp2, Tw2, It is the sum of Tsub2 and Tsup2. Since it is not easy to reduce the thickness of the optical device 105 and the electronic device 106, it is not easy to reduce Tp1 and Tp2. In addition, it is not easy to reduce the thicknesses Tsub1 and Tsub2 of the substrate 21 and the thickness Tsup2 of the support substrate 23 while maintaining the mechanical strength. For this reason, there is a problem that the optical module becomes large.

  FIG. 2 shows an example of an optical module in which the optical device 105 is arranged at the end of the optical waveguide. The optical module shown in FIG. 2 includes a PLC 22, a substrate 21, an optical device 105, and an optical bench 31. The PLC 22 includes an upper clad 22c, a core 22b, a lower clad 22a, and an end face 22d. The core 22b has a higher refractive index than the upper cladding 22c and the lower cladding 22a. The core 22b sandwiched between the upper clad 22c and the lower clad 22a functions as an optical waveguide. Reference numeral 41 denotes an optical path of light that is guided through the core 22b and emitted from the end face 22d, and light that enters the core 22b from the end face 22d. When the optical device 105 is disposed at the end of the PLC 22 as shown in FIG. 2, the PLC 22 and the optical device 105 must be optically coupled. Therefore, the optical device 105 is arranged on the optical bench 31 or the like, and the heights of the active layers of the core 22b and the optical device 105 are made to coincide. Then, the light passing through the optical path 41 is incident on the active layer of the optical element included in the optical device 105. Further, the light emitted from the optical device 105 is incident on the core 22b from the end face 22d.

  However, when the temperature changes, the heights of the active layers of the core 22b and the optical device 105 may not match due to the difference between the thermal expansion coefficients of the substrate 21 and PLC 22 and the optical bench 31. If it does so, the problem that the light radiate | emitted from the core 22b and propagates the optical path 41 will not enter into the active layer 102 of the optical element with which the optical apparatus 105 is provided arises. There is also a problem that light emitted from the optical device 105 does not enter the core 22b. Furthermore, the light emitted from the core 22b may not enter the active layer of the optical element included in the optical device 105 or the light emitted from the optical device 105 may not enter the core 22b due to warpage of the substrate. There was also a problem.

JP 2008-009302 A Japanese Patent Laid-Open No. 2004-177707

  In order to solve the above-described problems, an object of the present invention is to provide an optical module that is thinner than a conventional optical module and that can easily adjust an optical axis, and a method for manufacturing the same.

  In order to achieve the above object, in the optical module of the present invention, an optical device is disposed inside a groove provided in a substrate. The optical module manufacturing method of the present invention is an optical module manufacturing method of the present invention.

  Specifically, the optical module of the present invention includes a planar optical waveguide circuit disposed on a substrate, a groove provided on a surface of the substrate opposite to the surface on which the planar optical waveguide circuit is disposed, An optical device disposed inside the groove and configured to receive light incident on the planar optical waveguide circuit or to receive light emitted from the planar optical waveguide circuit.

  The optical module according to the present invention can reduce the thickness of the optical module by providing the substrate with a groove and disposing the optical device inside the groove. Since the optical device is arranged inside the substrate, the optical axis deviation between the planar optical waveguide circuit and the optical device due to temperature change is small compared to the case where the optical device is arranged on a different material such as an optical bench. In addition, since the place where the optical device inside the groove is disposed can be freely formed, the optical axis adjustment between the planar optical waveguide circuit and the optical device can be facilitated. Therefore, the present invention can provide an optical module that is thinner than a conventional optical module and that allows easy adjustment of the optical axis.

  In the optical module of the present invention, the planar optical waveguide circuit penetrates from the upper surface to the lower surface, connects the upper surface of the planar optical waveguide circuit and the groove, and between the planar optical waveguide circuit and the optical device. A mirror that is inserted into an optical path and reflects light from the optical device and makes the light incident on the planar optical waveguide circuit, or reflects light from the planar optical waveguide circuit and makes the light enter the optical device; , May be further provided.

  In the optical module of the present invention, the groove may include a plurality of bottom portions having different depths.

  In the optical module of the present invention, an end surface of the planar optical waveguide circuit that contacts the through hole may be inclined with respect to the optical axis direction of the planar optical waveguide circuit on which the end surface is disposed.

  Specifically, the optical module manufacturing method of the present invention includes a planar optical waveguide circuit forming step of forming a planar optical waveguide circuit on a substrate, a groove forming step of forming a groove in the substrate, and the planar optical waveguide. An optical device installation step in which an optical device that makes light incident on the circuit or receives light emitted from the planar optical waveguide circuit is installed inside the groove;

  Since the groove forming step and the optical device installing step are included, the groove can be formed on the substrate, and the optical device can be installed inside the groove. Therefore, an optical module with a small thickness can be manufactured. In the optical device installation process, since the optical device is installed on the substrate, the optical axis shift between the planar optical waveguide circuit and the optical device due to temperature change is smaller than when the optical device is installed on a different material such as an optical bench. can do. Further, in the groove forming step, a place where the optical device inside the groove is disposed can be freely formed, so that the optical axis adjustment between the planar optical waveguide circuit and the optical device can be facilitated. Therefore, the present invention can provide a method of manufacturing an optical module that is thinner than a conventional optical module and that allows easy adjustment of the optical axis.

  The optical module manufacturing method of the present invention is formed by penetrating from the upper surface to the lower surface of the planar optical waveguide circuit formed in the planar optical waveguide circuit forming step, and formed in the upper surface of the planar optical waveguide circuit and the groove forming step. A through-hole forming step for forming a through-hole that connects the grooves, and a light path between the planar optical waveguide circuit and the optical device to reflect light from the planar optical waveguide circuit to the optical device And a mirror installation step of installing a mirror that enters or reflects the light from the optical device and enters the planar optical waveguide circuit, after the groove forming step.

  In the method for manufacturing an optical module of the present invention, a plurality of bottom portions having different depths may be formed in the groove forming step.

  In the method for manufacturing an optical module according to the present invention, in the through hole forming step, an end surface in contact with the through hole may be inclined with respect to the optical axis direction of the planar optical waveguide circuit on which the end surface is arranged.

  The above inventions can be combined as much as possible.

  According to the present invention, it is possible to provide an optical module that is thinner than a conventional optical module and that can easily adjust the optical axis, and a method for manufacturing the same.

FIG. 2 is a configuration diagram of a surface-mount optical module related to the present invention, where (a) shows an example of an optical module in which an optical device 105 and an electronic device 106 are arranged on a PLC 22, and (b) 1 shows an example of an optical module in which the optical device 105 and the electronic device 106 are arranged. The block diagram of an example of the end surface mounting type optical module relevant to this invention is shown. It is a block diagram of the optical module which concerns on 1st embodiment of this invention, (a) shows an example of sectional drawing of the optical module 10 which concerns on 1st embodiment of this invention, (b) is 104z An enlarged view of an example of the indicated area is shown. It is a permeation | transmission figure of the optical module 10 which concerns on 1st embodiment of this invention, (a) shows an example of arrangement | positioning of the groove | channel 107 which has the same influence on the two optical waveguides of the Mach-Zehnder interferometer 24, ( b) shows an example of the arrangement of the grooves 107 that have different influences on the two optical waveguides of the Mach-Zehnder interferometer 24, and (c) shows line symmetry with respect to the portion of the optical waveguide that is not the Mach-Zehnder interferometer 24. (D) shows an example of the arrangement of the grooves 107 arranged axisymmetrically with respect to the portion of the optical waveguide that is not the Mach-Zehnder interferometer 24. It is a block diagram of an example of the optical module 10 which concerns on 1st embodiment of this invention, (a) shows the height of the wall 107a of the part with the bonding wire 108 between the optical apparatus 105 and the electronic apparatus 106. It is an example of a figure, (b) is an example of the figure which shows the height of the wall 107a of the part which does not have the bonding wire 108. FIG. It is a block diagram of an example of the optical module which concerns on 2nd embodiment of this invention, (a) shows sectional drawing, (b) shows a bottom view. The block diagram of an example of the end surface 22d of PLC22 of the optical module which concerns on 3rd embodiment of this invention is shown. The block diagram of an example of the end surface 22d of PLC22 of the optical module relevant to 3rd embodiment of this invention is shown. It is a block diagram of an example of a DP-QPSK (Dual Polarization Quadrature Phase Shift Keying) receiving module using the optical module according to the first embodiment, the second embodiment, or the third embodiment of the present invention, (A) shows a top view and (b) shows a bottom view.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to embodiment shown below. These embodiments are merely examples, and the present invention can be implemented in various modifications and improvements based on the knowledge of those skilled in the art. In the present specification and drawings, the same reference numerals denote the same components.

(First embodiment)
FIG. 3A shows a cross-sectional view of the optical module 10 according to the first embodiment of the present invention. FIG. 3B shows an enlarged view of the area indicated by 104z. The optical module 10 according to the present embodiment includes a substrate 21, a PLC 22, a mirror structure 104, an optical device 105, and an electronic device 106. The PLC 22 includes an end face 22d.

  The PLC 22 is disposed on the substrate 21. One surface of the PLC 22 in contact with the substrate 21 is a lower surface of the PLC 22, and the other surface of the PLC 22 is an upper surface of the PLC 22. One surface of the substrate 21 that contacts the PLC 22 is the upper surface of the substrate 21. The PLC 22 guides light. The substrate 21 and the PLC 22 include a through hole 109. The through hole 109 penetrates the upper surface and the lower surface of the PLC 22. The PLC 22 includes an end face 22 d that makes light incident on the PLC 22 incident or emits light emitted from the PLC 22 at a portion where the PLC 22 and the through hole 109 are in contact with each other.

  The through hole 109 functions as an optical path of light emitted from the end face 22d of the PLC 22 and an optical path of light incident on the PLC 22 from the end face 22d. The mirror structure 104 includes a mirror 104a. The mirror 104a is disposed with an inclination with respect to the upper surface of the substrate 21, reflects light emitted from the end face 22d, and changes the optical path of the light from the optical path 42a (horizontal direction) to the optical path 42b (vertical direction). The mirror 104a reflects the light incident on the end face 22d, and converts the optical path of the light from the optical path 42b to the optical path 42a.

  The shape of the through hole 109 is arbitrary. However, in the through hole 109, the light path 42a emitted from the PLC 22 is reflected by the mirror 104a and incident on the optical device 105, and the light path 42a emitted from the optical device 105 is reflected by the mirror 104a and reflected on the PLC 22. It is necessary to have a shape that does not attenuate in the path to the incidence. For example, the light path 42 a emitted from the PLC 22 should not be shaped so as to be scattered by hitting the side surface of the through hole 109.

  The substrate 21 includes a groove 107. The groove 107 is provided on the lower surface of the substrate 21, which is a surface opposite to the upper surface of the substrate 21 on which the PLC 22 is disposed, and accommodates the optical device 105 and the electronic device 106. A through hole 109 that penetrates the upper surface and the lower surface of the PLC 22 connects the upper surface of the PLC 22 and the groove 107. D 1 is the depth of the groove 107. Here, the depth of the groove 107 is a distance from the lower surface of the substrate 21 to the bottom 107 b of the groove 107. The bottom 107b of the groove 107 is a surface and functions as a bottom.

  The optical device 105 includes, for example, a photodiode (PD: Photo Diode) or a laser diode (LD: Laser Diode). The optical device 105 emits light incident on the PLC 22 and receives light emitted from the PLC 22. The optical device 105 may include a lens 105a on the light incident / exit surface. When the optical device 105 includes the lens 105a, light emitted from the optical element in the optical device 105 enters the PLC 22 via the lens 105a. The light propagating through the PLC 22 is incident on an optical element (not shown) in the optical device 105 through the lens 105a.

  The electronic device 106 includes, for example, a Trans-Impedance Amplifier (TIA). The electronic device 106 performs predetermined electrical conversion on the electrical signal output from the optical device 105 or the electrical signal input to the optical device 105. Reference numeral 108 denotes a bonding wire. The bonding wire 108 electrically connects the optical device 105 and the electronic device 106.

  The PLC 22 is formed on, for example, a semiconductor single crystal substrate 21. Examples of the material of the substrate 21 include semiconductor single crystal substrates such as Si single crystal, GaAs single crystal, and InP single crystal, glass, ceramic, plastic, and metal. The thickness of the substrate 21 is approximately 500 μm or more and 1000 μm or less. The thickness of the optical element constituting the optical device 105 and the electronic component constituting the electronic device 106 is about several hundred μm. That is, the thickness of the substrate 21 is several times the thickness of the optical elements and electronic components that constitute the optical device 105 and the electronic device 106.

  As shown in FIG. 3A, at least a part of the optical device 105 and the electronic device 106 can be accommodated in a groove 107 provided in the substrate 21. The substrate 21 also has mechanical strength for housing and holding the optical device 105 and the electronic device 106. That is, by disposing the optical device 105 or the like in the space where the groove 107 is formed, the thickness as the optical module 10 can be reduced by about several hundred μm compared to the case where the optical device 105 or the like is disposed on the upper surface of the PLC 22. . If the optical elements and electronic components constituting the optical device 105 and the electronic device 106 are completely accommodated in the groove 107, the thickness of the optical module is equal to the thickness of the optical device 105 or the electronic device 106, the PLC 22 and the substrate 21. Is the sum of the thicknesses of the PLC 22 and the substrate 21. Therefore, in order to reduce the thickness of the optical module, the depth of the groove 107 is made deeper than the height of the optical device 105 and the electronic device 106. The optical device 105 and the electronic device 106 are accommodated in the groove 107. However, it is not an essential requirement to make the depth of the groove 107 deeper than the height of the optical device 105 and the electronic device 106.

  The depth D1 of the groove 107 where the optical device 105 is disposed is as deep as possible. This is not only for completely accommodating the optical device 105 and the electronic device 106 in the groove 107 but also for shortening the distance between the optical device 105 and the mirror 104a. By shortening the distance between the optical device 105 and the mirror 104a, the optical path 42b is shortened. As the optical path 42b is longer, the light passing through the optical path 42b is diffused, and the optical axis adjustment of the optical device 105 and the mirror structure 104 becomes difficult. Therefore, as the depth of the groove 107 where the optical device 105 is disposed is deeper, the optical axis of the optical device 105 and the mirror structure 104 can be adjusted easily. For example, the groove 107 may reach from the lower surface of the PLC 22 to a position of about 50 μm that is substantially equal to the thickness of the PLC 22.

  When the groove 107 is arranged, the position of the optical waveguide in the PLC 22 is taken into consideration. This is because the effective refractive index of the optical waveguide may be affected depending on where the groove 107 is disposed. For example, assume that two optical waveguides constitute a Mach-Zehnder interferometer. In that case, the groove 107 is disposed at a position that affects the two optical waveguides constituting the Mach-Zehnder interferometer symmetrically or evenly, or at a position that does not affect the two optical waveguides. Place. Here, to affect the two optical waveguides symmetrically or evenly means, for example, that the same effective refractive index change is exerted.

  The position where the groove 107 is disposed will be described with reference to FIG. FIG. 4 is a perspective view of the PLC 22 as viewed from above. Reference numeral 24 denotes a Mach-Zehnder interferometer. The Mach-Zehnder interferometer 24 includes an optical waveguide 24b and an optical waveguide 24c as two optical waveguides. An optical waveguide 24a and an optical waveguide 24d are disposed at a portion where the optical waveguides 24b and 24c intersect. The optical waveguide 24a and the optical waveguide 24d are not in contact but are arranged in the same straight line. The distance from the straight line L0 connecting the optical waveguide 24a and the optical waveguide 24d is the same for the optical waveguide 24b and the optical waveguide 24c. L1 is the distance from L0 to the side wall surface of the groove 107 in the direction of the optical waveguide 24b. L2 is the distance from L0 to the side wall surface of the groove 107 in the direction of the optical waveguide 24c. The through hole 109 is disposed inside the groove 107.

  FIG. 4A shows an arrangement example of the optical waveguide 24b which is the two optical waveguides constituting the Mach-Zehnder interferometer 24 and the groove 107 which affects the optical waveguide 24c symmetrically or equally. In FIG. 4A, the groove 107 is arranged at a position where L1 and L2 are equal. Since L1 and L2 are equal, the groove 107 is arranged symmetrically with respect to the optical waveguide 24d. Since the groove 107 is arranged symmetrically with respect to the optical waveguide 24d, the effective refractive index change of the optical waveguides 24b and 24c due to the arrangement of the groove 107 is the same. However, the groove 107 should not be arranged as shown in FIG. This is because, in FIG. 4B, L2 is larger than L1, and the effective refractive index is different between the optical waveguide 24b and the optical waveguide 24c.

  FIG. 4C and FIG. 4D show an example of arrangement of the optical waveguide 24b, which is the two optical waveguides constituting the Mach-Zehnder interferometer 24, and the groove 107 that does not affect the optical waveguide 24c. 4C and 4D, the groove 107 is disposed at a position that does not overlap the optical waveguide 24b and the optical waveguide 24c. If the Mach-Zehnder interferometer 24 has no influence on the characteristics, or if the optical waveguide has a slight change in the effective refractive index and does not affect the characteristics of the Mach-Zehnder interferometer 24, the groove 107 may be arranged at any location. . For example, as shown in FIG. 4D, even if L1 and L2 are not equal, the characteristics of the Mach-Zehnder interferometer 24 are not affected.

  In arranging the grooves 107, the substrate 21 is designed so as not to have a portion having a weak mechanical strength such as a chipping of the substrate 21, and the thickness of the substrate 21 capable of maintaining the mechanical strength is ensured. In order to increase the mechanical strength of the substrate 21, a wall 107 a may be provided inside the groove 107. Further, the inside of the groove 107 may be divided into two locations by the wall 107a, where the optical device 105 is disposed and where the electronic device 106 is disposed.

FIG. 5 shows an example in which the wall 107 a is disposed in the groove 107. When the optical device 105 and the electronic device 106 are completely accommodated in the groove 107, it is desirable that the height H ₁₀₇ of the wall 107a is set to a height at which the bonding wire 108 does not contact as shown in FIG. . For example, the height _{H 107} of the wall 107 with a height less than _{H 106} height _{H 105} and the electronic device 106 of the optical device 105. Note that as in FIG. 5 (a), the height _{H 107} of the wall 107a, may be a constant height _{H 106} of the height _{H 105} and the electronic device 106 of the optical device 105.

Further, as shown in FIG. 5B, the height H ₁₀₇ of the wall 107 a may be equal to the depth D 1 of the groove 107. Thereby, since the groove | channel 107 is supported by the wall 107a, a deformation | transformation of the board | substrate 21 with which the groove | channel 107 is arrange | positioned can be prevented. In this case, in order not to bring the bonding wire 108 into contact with the wall 107, it is desirable to provide an opening or a cutout for allowing the bonding wire 108 to pass through the wall 107a.

  In addition, since the groove 107 in which the optical device 105 is disposed is disposed on the lower surface of the substrate 21 and the PLC 22 is disposed on the upper surface of the substrate 21, the influence of expansion and contraction of the substrate 21 due to temperature change is affected by the PLC 22 and the optical device. It is equal to 105. As described above, in the present embodiment, the optical device 105 is disposed inside the groove 107, so that the optical axis shift between the PLC 22 and the optical device 105 due to temperature change can be optically applied to different materials such as the optical bench 31. Compared with the case where the apparatus 105 is arrange | positioned, it can be made small.

  Further, it is desirable to form the portion where the mirror structure 104 is disposed and the portion where the optical device 105 is disposed by etching. This is because the shape, position, and size of the arrangement site can be processed with high precision by etching. For this reason, it is easy to make a shape in which the portion where the mirror structure 104 is arranged or the portion where the optical device 105 is arranged can be fitted, or to form an alignment marker. By this processing, the mirror structure 104 and the optical device 105 can be arranged at predetermined positions, so that the optical axis can be easily adjusted. In addition, for example, it is easy to form a frame structure that matches the shape of the mirror structure 104 or the optical device 105 in a portion where the mirror structure 104 or the optical device 105 is disposed. Therefore, if the mirror structure 104 and the optical device 105 are fitted in a frame, the optical axis can be easily adjusted.

(Second embodiment)
FIG. 6 shows a cross-sectional view and a bottom view of an optical module 40 according to the second embodiment of the present invention. The difference between the optical module 10 according to the first embodiment of the present invention and the optical module 40 according to the second embodiment of the present invention is the depth of the groove 107. In the optical module 10 according to the first embodiment shown in FIG. 3A, the depth of the groove 107 where the optical device 105 and the electronic device 106 are arranged is the same at D1. However, in the optical module 40 according to this embodiment shown in FIG. 6, the groove 107 has a plurality of bottom portions, the optical device 105 is disposed on one bottom portion, and the electronic device 106 is disposed on one bottom portion. Is done. The depth of the groove 107 where the optical device 105 is disposed is D1, while the depth of the groove 107 where the electronic device 106 is disposed is D2. The height _{H 105} of the optical device 105 is higher than the height _{H 106} of the electronic device 106, D1 is greater than D2.

It is desirable to make the depth D1 that is the maximum depth of the plurality of bottom portions as deep as possible. By increasing the depth D1 of the groove 107, the optical device 105 and the electronic device 106 are completely accommodated in the groove 107, and the distance between the optical device 105 and the mirror 104a can be shortened. However, the optimum D2 varies depending on the height of the electronic component included in the electronic device 106. Specifically, it is desirable that D2 has such a depth that the optical device 105 and the electronic device 106 can be connected by the bonding wire 108 and the length of the bonding wire 108 can be shortened. For example, D2 is determined so that the heights of the lower surfaces of the optical device 105 and the electronic device 106 are substantially the same. For example, the difference between D1 and _D2, and _{H 105,} equal to the difference between the _{H 106.} The depth of the groove 107 is only one type of D1 in FIG. 3A, and is two types of D1 and D2 in FIG. When the electronic device 106 includes a plurality of elements, etc., the depth of the groove 107 is not limited to one type or two types, but may have any number of types of the depth of the groove 107. Moreover, you may arrange | position the wall 107a in the groove | channel 107 similarly to 1st embodiment.

  In the optical module 10 according to the first embodiment and the optical module 40 according to the present embodiment, the light guided through the PLC 22 is emitted from the end face 22d, passes through the optical path 42a, is reflected by the mirror 104a, passes through the optical path 42b, The light enters the optical device 105. The light incident on the PLC 22 is emitted from the optical device 105, passes through the optical path 42b, is reflected by the mirror 104a, passes through the optical path 42a, and enters the PLC 22 from the end face 22d.

  Here, in the optical module 10 and the optical module 40, when light propagates between the PLC 22 and the optical device 105, the interfaces having different refractive indexes through which the light passes are the interface between the PLC 22 and the air formed by the end face 22d, and the optical device. Desirably, there are only two interfaces, 105 and air. For example, when the through hole 109 of the optical module 10 and the optical module 40 is filled with resin, the interface with different refractive index through which light passes is the interface between the PLC 22 and the resin in addition to the interface between the optical device 105 and the air. It becomes an interface between resin and air, and increases by one.

  In addition, when a transparent substrate for fixing the optical element 105 is further disposed between the optical element 105 and the substrate 21 of the optical module 10 and the optical module 40, the interfaces having different refractive indexes through which light passes are In addition to the interface between the optical device 105 and the air, the interface between the PLC 22 and the resin, the interface between the resin and the transparent substrate, and the interface between the transparent substrate and the air are further increased by one. As the number of interfaces having different refractive indexes through which light passes increases, light reflection and loss increase. Therefore, the optical module 10 and the optical module 40 having two interfaces having different refractive indexes through which light passes can suppress reflection and loss of propagating light.

(Third embodiment)
FIG. 7 shows an example of the inclined end face 22d of the optical module according to the third embodiment of the present invention. In the present embodiment, the angle of the inclined end surface 22d is α1, and the angle of the mirror 104a is β1. α1 is an angle formed by the upper surface of the PLC 22 and the end surface 22d of the PLC 22, and β1 is an angle formed by the upper surface of the mirror structure 104 and the surface on which the mirror 104a is disposed. Here, the upper surface of the mirror structure 104 is a surface facing the surface of the mirror structure 104 where the mirror structure 104 and the substrate 21 are in contact.

  As shown in FIG. 8, when the angle β1 of the mirror 104a is 45 degrees, the light 43a emitted from the PLC 22 enters the optical device 105 perpendicularly. For this reason, the light 43a is reflected by the optical device 105, becomes light 43b, and may enter the PLC 22. In this case, if the incident surface or the exit surface of the optical device 105 shown in FIG. 8 is arranged to be inclined with respect to the incident light 43a, the problem of the light 43b entering the PLC 22 can be solved. However, since the optical device 105 is fixed to the substrate 21 with solder or an adhesive, it is not easy to accurately place the incident surface or the light emitting surface of the optical device 105 with respect to the light 43a.

  Therefore, in this embodiment, the end face 22d is inclined as shown in FIG. The inclined end surface 22d is perpendicular to the optical path surface formed by the light 43a and the light 43b, and is inclined so that an angle formed with the upper surface of the PLC 22 is α1. The angle of the mirror 104a is β1. α1 and β1 are angles smaller than 90 degrees, for example, 80 degrees and 45 degrees. The angles α1 and β1 are determined so that the optical coupling between the PLC 22 and the optical device 105 is maximized.

  In the present embodiment, since the PLC 22 includes the inclined end surface 22d, the light 43a is incident on the optical device 105 at an angle, and the reflected light 43b is incident on the end surface 22d off the waveguide core 22b of the PLC 22. It can prevent entering into the waveguide core 22b of PLC22. Therefore, in the present embodiment, the PLC 22 having the inclined end face 22d can prevent the signal propagating in the PLC 22 from deteriorating.

  The inclined end surface 22d according to this embodiment can be used in combination with the optical module 10 according to the first embodiment and the optical module 40 according to the second embodiment.

(Fourth embodiment)
FIG. 9 shows a configuration diagram of an example of the optical module 50 according to the present embodiment. The optical module 50 according to the present embodiment is an example in which the optical module according to the first to third embodiments of the present invention is applied to a dual polarization quadrature phase shifting keying (DP-QPSK) module.

  The optical module 50 includes an optical signal processing unit 51, an OE (Optical / Electrical) conversion unit 52, a wiring board 511, and a flexible printed circuit (FPC) 512. The optical signal processor 51 includes a polarization beam splitter (PBS) 501, a beam splitter (BS) 502, a 90-degree optical hybrid 503, and a mirror structure 104. Although not explicitly shown in FIG. 9, the mirror structure 104 includes a mirror 104a. The OE conversion unit 52 includes an optical device 105 and an electronic device 106.

  Of the optical signal processing unit 51, the PBS 501, the BS 502, and the 90-degree optical hybrid 503 are arranged in the PLC 22. The OE converter 52 is disposed in the groove 107 provided on the surface opposite to the surface on which the PLC 22 is disposed.

Of the signal light and local light input to the optical module 50, the signal light is incident on the PBS 501 and the local light is incident on the BS 502. The PBS 501 separates and outputs the TE polarization component and the TM polarization component of the incident signal light. The BS 502 divides the input local light into two so that the light intensities are equal and outputs the light. The TE polarization component from the PBS 501 and the local light from the BS 502 are input to the 90-degree optical hybrid 503TE.
The TM polarization component from the PBS 501 and the local light from the BS 502 are input to the 90-degree optical hybrid 503TM. The 90-degree optical hybrids 503TE and 503TM combine and output incident light. The respective output lights from the 90-degree optical hybrids 503TE and 503TM are guided to the surface opposite to the surface on which the PLC 22 is arranged by the mirror 104a included in the mirror structure 104 and input to the optical device 105. Light incident on the optical device 105 is converted into an electrical signal and input to the electronic device 106. An output signal of the electronic device 106 is output to the flexible substrate 512 via the wiring substrate 511.

  The device included in the OE converter 52 is accommodated in the groove 107. Therefore, the thickness of the optical module 50 is thinner than when the device included in the OE converter 52 is disposed on the surface of the substrate 21.

(Fifth embodiment)
This embodiment is a method for manufacturing the optical module 10 according to the first embodiment of the present invention and the optical module 40 according to the second embodiment. Moreover, this embodiment can also be applied to manufacture of the inclined end surface 22d of the optical module according to the third embodiment of the present invention. The method for manufacturing an optical module according to the present embodiment includes a planar optical waveguide circuit forming step, a groove forming step, a through hole forming step, a mirror installation step, and an optical device installation step. In the planar optical waveguide circuit forming step, the PLC 22 is formed. In the groove forming step, the groove 107 is formed. In the through hole forming step, the through hole 109 is formed. In the mirror installation step, the mirror structure 104 including the mirror 104a is installed.

  First, a planar optical waveguide circuit forming process that is a process of forming the PLC 22 will be described. This process is a process common to the optical module 10 according to the first embodiment and the optical module 40 according to the second embodiment. In the planar optical waveguide circuit forming step, an optical waveguide circuit and an optical circuit included in the PLC 22 are formed.

  First, a lower clad layer 22a made mainly of quartz glass or the like is laminated on a substrate such as Si. Next, a core layer 22b having a refractive index higher than that of the lower cladding layer 22a is laminated on the lower cladding layer 22a. Next, a necessary waveguide pattern is formed in the core layer 22b. Next, the upper cladding layer 22c is laminated. A waveguide type optical functional circuit and a waveguide region are produced on the substrate 21 by such a procedure.

  In producing the waveguide type optical functional circuit and the waveguide region of the PLC 22, the position of the orientation flat (orientation flat) indicating the crystal axis direction of the wafer is used as a reference. Since the degree of freedom in designing the waveguide pattern is high, the waveguide pattern is formed in consideration of the installation position of the optical device 105 and the like. The signal light propagates in the waveguide manufactured through the process as described above. Note that the end face 22d of the PLC 22 may be formed in the planar optical waveguide circuit forming step. When the end surface 22d is inclined, the inclined end surface 22d is inclined with respect to the optical axis direction of the PLC 22 perpendicular to the optical path surface. Further, after the optical waveguide circuit and the optical circuit included in the PLC 22 are formed, electrical wiring may be formed on the upper clad layer 22c.

  Next, a groove forming process that is a process of forming the groove 107 will be described. In the groove forming step, a groove 107 for installing at least the optical device 105 and the electronic device 106 is formed. This process is different between the optical module 10 according to the first embodiment and the optical module 40 according to the second embodiment. First, the groove forming process of the optical module 10 according to the first embodiment having no step inside the groove 107 will be described. First, in accordance with the shape of the waveguide type optical functional circuit in the PLC 22 on the upper surface and the waveguide region, the position where the optical device 105 on the lower surface side is installed is determined.

  Next, a groove 107 is formed from the lower surface of the substrate 21 by etching or cutting at a place where the optical device 105 or the like on the lower surface of the substrate 21 is installed. Since the groove 107 is formed from the lower surface of the substrate 21, an opening of the groove 107 is formed on the lower surface of the substrate 21. Examples of the etching method include dry etching by the BOSCH method and wet etching. The groove 107 is formed based on the position of the orientation flat of the wafer. The groove 107 is formed on the lower surface of the substrate 21 on which the PLC 22 is formed on the upper surface. Further, since the PLC 22 and the groove 107 are formed based on the position of the orientation flat of the wafer, the alignment when forming the groove 107 can be easily performed based on the position of the orientation flat or the arrangement of the optical circuit or the like. Can do.

  The depth of the groove 107 (distance from the lower surface of the substrate 21 to the bottom of the groove) is D1. Further, a through hole for electrical wiring that penetrates from the lower surface of the substrate 21 to the surface of the PLC 22 may be formed simultaneously with the formation of the groove 107 or after the formation of the groove 107. The groove 107 formed from the lower surface of the substrate 21 extends from the lower surface of the PLC 22 to a position of about 50 μm, which is substantially equal to the thickness of the PLC 22.

  Electrical wiring may be formed on the lower surface of the substrate 21 before the groove forming step or after the groove forming step. Here, the electrical wiring to be formed is, for example, an in-module wiring for driving the optical device 105 and the electronic device 106 and for signal transmission. In addition, the electrical wiring and the optical device 105 and the electronic device 106 and the electrical wiring and other chips mounted on the module are connected by wire bonding or solder bumps.

  Further, an alignment marker may be formed in order to facilitate alignment when installing the optical device 105. Further, the installation location of the optical device 105 may be a shape that allows the optical device 105 to be fitted together. A wall 107a may be formed inside the groove.

  Next, the groove forming process of the optical module 40 according to the second embodiment will be described. The difference between the groove forming process used by the optical module 10 according to the first embodiment and the optical module 40 according to the second embodiment is that etching or cutting is performed at a location where the optical device 105 or the like on the lower surface of the substrate 21 is installed. This is a portion where the groove 107 is formed from the lower surface of the substrate 21. In the optical module 10 according to the first embodiment, as shown in FIG. 3A, the depth of the groove 107 is only one level D1, but the groove 107 provided in the optical module 40 according to the second embodiment. As shown in FIG. 6, it has a depth of two steps of grooves D1 and D2. The depth of the groove 107 may be a three-stage structure or more.

  The optical module 40 according to the second embodiment having the depths of the plurality of grooves 107 performs etching a plurality of times in order to form the grooves 107. The etching method is the same as the groove forming step of the optical module 10 according to the first embodiment. The step structure determines the number of steps, the step size, the depth of the groove, and the like in consideration of the size of the optical device 105 and electronic device 106 and the relationship with the external terminals. Note that electrical wiring may be formed on the lower surface of the substrate 21 before or after the groove forming step. Further, an alignment marker may be formed in order to facilitate alignment when installing the optical device 105. Further, the installation location of the optical device 105 may be a shape that allows the optical device 105 to be fitted together. A wall 107a may be formed inside the groove.

  Next, a through hole forming process, which is a process of forming a through hole penetrating from the upper surface of the PLC 22 to the groove 107, will be described. This process is a process common to the optical module 10 according to the first embodiment and the optical module 40 according to the second embodiment. In the through hole forming step, as shown in FIG. 3B, a through hole 109 that functions as an optical path of light emitted from the PLC 22 and an optical path of light incident on the PLC 22 is formed.

  A predetermined position of the PLC 22 on the groove 107 is etched from the upper surface side of the PLC 22. By etching, a through hole 109 connecting the upper surface of the PLC 22 and the groove 107 and the end surface 22d of the PLC 22 are formed from the upper surface of the PLC 22 through the lower surface of the PLC 22 and the substrate 21.

  In the next mirror installation step, the PLC 22 where the mirror structure 104 is installed is also removed by etching. Alternatively, the through hole 109 may be formed by penetrating the substrate 21 by etching after removing the PLC 22 above the through hole 109 and the PLC 22 at the installation location of the mirror structure 104 by etching. Further, in order to facilitate the arrangement of the mirror structure 104, the alignment marker may be formed after removing the PLC 22 where the mirror structure 104 is installed. Further, the installation location of the mirror structure 104 may be a shape that allows the mirror structure 104 to be fitted together.

  When the inclined end surface 22d according to the third embodiment is used in combination with the optical module 10 according to the first embodiment and the optical module 40 according to the second embodiment, the end surface 22d is further processed, An inclined end face 22d may be formed as shown in FIG. For example, the end surface 22d of the PLC 22 is shaved by dry etching or wet etching, so that the end surface 22d becomes an end surface 22d that is perpendicular to the optical path surface and inclined with respect to the optical axis direction.

  Next, a mirror installation process that is a process of installing the mirror structure 104 including the mirror 104a in the groove 107 and an optical apparatus installation process that is a process of installing the optical device 105 and the like in the groove 107 will be described. This process is a process common to the optical module 10 according to the first embodiment and the optical module 40 according to the second embodiment. The mirror structure installation step is a step of installing the mirror structure 104 including the mirror 104 a on the substrate 21. The optical device installation step is a step of installing the optical device 105 in the groove 107.

  First, the mirror installation process will be described. As shown in FIG. 3B, the mirror structure 104 is installed on the portion of the substrate 21 where the PLC 22 is removed. Specifically, the mirror structure 104 is installed at a predetermined position using an alignment marker, an installation frame, or the like as a mark. If an adhesive (such as an ultraviolet curable resin or a thermosetting resin) is applied in advance to the place where the mirror structure 104 is installed, the mirror structure is adjusted by irradiating the adhesive with ultraviolet rays or heat treatment after adjusting the optical axis. The body 104 can be easily fixed. The part from which the PLC 22 is removed is provided in the through hole forming step. A commercial product may be used for the mirror structure 104. When the mirror structure 104 is manufactured, the mirror 104a is formed by, for example, vapor deposition of a metal film after forming an inclined surface for forming the mirror 104a in the mirror structure 104 by etching or the like.

  Next, the optical device installation process will be described. As shown in FIG. 3A, the optical device 105 is installed in the groove 107. Although the installation of the optical device 105 has been described here, the electronic device 106 may be installed at the same time as the optical device 105.

  The optical device 105 is installed inside the groove 107 instead of on the optical bench 31 or the like. The groove 107 in which the optical device 105 is installed is installed on the lower surface of the substrate 21, and the PLC 22 is installed on the substrate 21. The optical device 105 can be fixedly installed inside the groove 107 in the same process as the mirror structure 104. Therefore, since the optical device 105 is installed inside the groove 107, the optical axis shift between the PLC 22 and the optical device 105 due to temperature change is caused when the optical device 105 is arranged on a different material such as the optical bench 31. Smaller than that.

  The order of installation of the mirror structure 104 and installation of the optical device 105 may be changed according to the optical element provided in the optical device 105. For example, in the case of an optical element such as a PD that does not require strict optical axis alignment, after the mirror structure 104 having the mirror 104a having a reflection surface of 45 degrees with respect to the surface of the substrate 21 is first installed, May be installed.

  On the other hand, when an optical element such as an LD is used, after the LD is installed, the direction of the mirror structure 104 is adjusted, and the mirror 104a is fixed at an optimal position. Here, the optimum position is a position where the amount of light emitted from the optical device 105, reflected by the mirror 104a, and propagated through the PLC 22 is maximum, or propagated through the PLC 22 and reflected by the mirror 104a. This is the position where the amount of light incident on the optical device 105 is maximized.

  The optical module and the manufacturing method thereof of the present invention can be applied to the communication industry.

10: optical module 102: active layer 104 of optical element: mirror structure 104a: mirror 104z: mirror structure peripheral portion 105: optical device 105a: lens 106: electronic device 107: groove 107a: wall 107b provided in the groove : Groove bottom 108: Bonding wire 109: Through hole 21: Substrate 22: PLC
22a: lower clad 22b: core 22c: upper clad 22d: end face 23: support substrate 24: Mach-Zehnder interferometers 24a, 24b, 24c, 24d: optical waveguide 31: optical bench 40: optical module 41: optical path 42a: optical path 42b: Optical path 43a: Light 43b: Light 50: DP-QPSK reception module 51: Optical signal processing unit 52: OE conversion unit 501: Polarization separator 502: Two branching unit 503: 90 degree optical hybrid 511: Wiring board 512: Flexible board

Claims (8)

A planar optical waveguide circuit disposed on a substrate;
A groove provided on a surface of the substrate opposite to the surface on which the planar optical waveguide circuit is disposed;
An optical device disposed inside the groove and receiving light incident on the planar optical waveguide circuit or receiving light emitted from the planar optical waveguide circuit;
An optical module comprising: A through hole penetrating from the upper surface to the lower surface of the planar optical waveguide circuit, and connecting the upper surface of the planar optical waveguide circuit and the groove;
Inserted in the optical path between the planar optical waveguide circuit and the optical device, reflects light from the optical device and enters the planar optical waveguide circuit, or reflects light from the planar optical waveguide circuit A mirror for making light incident on the optical device;
Further comprising
The optical module according to claim 1. The groove includes a plurality of bottom portions having different depths.
The optical module according to claim 1 or 2. An end surface in contact with the through hole in the planar optical waveguide circuit is inclined with respect to the optical axis direction of the planar optical waveguide circuit on which the end surface is disposed.
The optical module according to claim 1. A planar optical waveguide circuit forming step of forming a planar optical waveguide circuit on the substrate;
A groove forming step of forming a groove in the substrate;
An optical device installation step of installing an optical device that makes light incident on the planar optical waveguide circuit or receives light emitted from the planar optical waveguide circuit inside the groove;
In order,
Optical module manufacturing method. A through-hole that penetrates from the upper surface to the lower surface of the planar optical waveguide circuit formed in the planar optical waveguide circuit forming step, and connects the upper surface of the planar optical waveguide circuit and the groove formed in the groove forming step. A through hole forming step to be formed;
In the optical path between the planar optical waveguide circuit and the optical device, the light from the planar optical waveguide circuit is reflected and incident on the optical device or the light from the optical device is reflected to reflect the planar optical waveguide circuit. A mirror installation process for installing a mirror to be incident on the mirror;
After the groove forming step,
The optical module manufacturing method according to claim 5. In the groove forming step, a plurality of bottom portions having different depths are formed.
The optical module manufacturing method according to claim 5 or 6. In the through-hole forming step, an end surface in contact with the through-hole is inclined with respect to the optical axis direction of the planar optical waveguide circuit on which the end surface is disposed.
The optical module manufacturing method in any one of Claim 5 to 7.

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