Optical module and method for mounting optical module

Abstract

Provided is an optical module 10 comprising an optical waveguide substrate 12 that is provided with an arrayed waveguide grating, and a laser diode 11 that couples an optical signal to the arrayed waveguide grating, wherein the arrayed waveguide grating is configured from a slab waveguide 14a having a coupling surface 14aa to which laser light of the laser diode 11 is coupled, a plurality of arrayed waveguides 19a connected with the slab waveguide 14a, and a slab waveguide 14b connected with the plurality of arrayed waveguides 19a, and the slab waveguide 14a is disposed such that, when viewed from above, at least part of the coupling surface 14aa is in contact with an end surface 12 facing the laser diode 11 of the optical waveguide substrate 12, or the coupling surface 14aa is located in a space outside the optical waveguide substrate 12 and the end surface 12 crosses the slab waveguide 14. This makes it possible to provide an optical module that achieves a reduction in the number of components by using a planar light wave circuit type filter, thereby being favorable for size reduction, simplification of a mounting process, and improvement in manufacturing yield.

Description

[Technical field]

[0001] The present invention relates to an optical module and a method for mounting an optical module. [Background technology]

[0002] As data communication speeds and volumes increase, optical communication devices and optical interconnection technologies are becoming more advanced. In optical communication devices, instead of using single-function optical devices such as conventional laser diodes (LD), photodiodes (PD), and optical waveguide filters, there is an increasing need for multi-channel, multi-function, and highly functional integrated modules that combine multiple elements and house them in one package. In addition, there is a demand for these modules to be compact and low-cost.

[0003] 1 is a diagram for explaining a known optical module, and shows the top surface of an optical transmission module 100. The optical transmission module 100 includes a plurality of laser diodes 110a to 110d each having a different wavelength, a planar lightwave circuit (PLC) type filter 112 for multiplexing the laser beams, and a plurality of lenses 111 for focusing the laser beams on the planar lightwave circuit type filter 112, all of which are housed in a package 150. The planar lightwave circuit type filter 112 includes an input waveguide 113a to which the laser beam is input, an output waveguide 113b from which the laser beam input to the waveguide is output, a plurality of arrayed waveguides 119 disposed between the input waveguide 113a and the output waveguide 113b, and slab waveguides 114a and 114b disposed at both ends of the arrayed waveguide 119.

[0004] The beam diameters of the lights output from the laser diodes 110a to 110d are converted via a lens 111 and are coupled to an input waveguide 113a. The light multiplexed through the arrayed waveguide is output from an output waveguide 113b and coupled to an optical fiber 118 via lenses 115 and 117, an isolator 116, etc. In addition, the optical transmission module 100 includes an electric circuit for controlling the operation of the laser diodes, a temperature controller, etc., which are not shown.

[0005] Such planar lightwave circuit type filters are described in, for example, Non-Patent Document 1 and Non-Patent Document 2. Both Non-Patent Document 1 and Non-Patent Document 2 aim at miniaturizing optical assemblies, and Patent Document 1 describes a configuration using a TFF (thin film filter) using multilayer film reflection instead of a planar lightwave circuit type filter. Although FIG. 1 describes a configuration in which four laser diodes are integrated, when the number of integrated laser diodes is further increased, a configuration using a planar lightwave circuit type filter is more advantageous than a TFF in terms of reducing variations in optical characteristics and miniaturization. Non-Patent Document 2 describes an arrayed waveguide grating as a planar lightwave circuit type filter. A Demux (Demultiplexer) circuit using an arrayed waveguide grating is composed of a plurality of input waveguides, a slab waveguide, an arrayed waveguide, a slab waveguide, and an output waveguide, and output light from the laser diode is coupled to a waveguide end face of the planar lightwave circuit via a lens. Since the numerical aperture (NA) of optical semiconductors and that of planar lightwave circuit waveguides differ greatly, low-loss connection is difficult, and SSCs (Spot Size Converters) are introduced to the end faces of bulk lenses, optical semiconductors, and quartz PLC waveguides.

[0006] In the example of the optical transmission module 100 shown in Fig. 1, for example, laser light output from one laser diode 110a is converted into a parallel beam by two lenses 111, 111, and focused on an input waveguide 113a. However, the configuration of the optical coupling section A, which is the portion between the laser diode 111 and the input waveguide 113a (shown by the dashed line), is not limited to the example shown in Fig. 1, and may be, for example, a configuration including one lens or a configuration including three lenses.

[0007] However, if only one lens is used to focus the laser light on the input waveguide in the optical coupling section A in order to miniaturize the package, the tolerance for the allowable error for component mounting deviation becomes strict, the mounting becomes more difficult, and it becomes difficult to improve the manufacturing yield of the optical module. In addition, if the number of lenses is increased, the space required for installing the lens components in the package of the optical module becomes large, which hinders miniaturization. Furthermore, the number of components increases, which increases the component cost, mounting cost, and mounting process, which is also disadvantageous for cost reduction. Furthermore, the configuration in which an optical waveguide is used to input the laser light to the planar lightwave circuit type filter 112 requires space to route the input waveguide 113a to the slab waveguide 114a so as not to cause bending loss, which is also disadvantageous for miniaturization of the optical module.

[0008] In recent years, the wavelength interval of integrated laser light has become narrower. Accordingly, high accuracy of the oscillation wavelength of laser diodes has been required. Also, high accuracy of the transmission wavelength and high rectangular filter characteristics have been required for the filter characteristics of arrayed waveguides. If the oscillation wavelength of the laser diode and the transmission wavelength of the arrayed waveguide deviate from the design, the combined optical characteristics will deteriorate, but the narrowing of the wavelength interval of the signal light has made it more difficult to match the two. It is considered that the central wavelengths of the laser and the filter will deviate due to manufacturing errors. Therefore, in the future, even higher accuracy of the oscillation wavelength and filter characteristics of laser diodes will be required, and with the expansion of the signal band, the tolerance of the oscillation wavelength of the laser diode and the transmission wavelength of the arrayed waveguide diffraction grating is also becoming stricter. For this reason, the performance of optical modules is also required to have high-precision control of the filter wavelength in wavelength division multiplexing communication and high-precision control of the oscillation wavelength of the laser diode. However, miniaturization of optical modules requires more sophisticated assembly and alignment of laser diodes and arrayed waveguide diffraction gratings, making it difficult to match the oscillation wavelength and transmission wavelength with high precision. [Prior art documents] [Non-patent literature]

[0009] [Non-Patent Document 1] Shigeru Kanazawa et al., “High Output Power and Compact LAN-WDM EADFB Laser TOSA for 4 × 100-Gbit / s / λ 40-km Fiber-Amplifier Less Transmission”, OFC 2020, M1F.2 [Non-Patent Document 2] Yoshiyuki Doi et al., “Compact ROSA for 100-Gb / s (4 × 25 Gb / s) Ethernet with a PLC-based AWG demultiplexer”, NW1J.5.pdf OFC / NFOEC Technical Digest. Summary of the Invention

[0010] The present invention has been made in consideration of the above points, and relates to an optical module and a mounting method thereof, which uses a planar lightwave circuit type filter to reduce the number of parts, which is advantageous in terms of miniaturization, simplification of the mounting process, and improvement of manufacturing yield, and which is capable of adjusting the oscillation wavelength and transmission wavelength during the mounting process even if the oscillation wavelength of the laser and the transmission wavelength of the filter deviate slightly from the design values ​​due to manufacturing errors of the parts.

[0011] In order to achieve the above object, an optical module according to an embodiment of the present disclosure includes an optical waveguide substrate having an arrayed waveguide grating, and a waveguide for transmitting an optical signal to the arrayed waveguide grating. a light-emitting element for outputting an optical signal from the arrayed waveguide grating or a light-receiving element for inputting an optical signal from the arrayed waveguide grating and, wherein the arrayed waveguide grating is signal a first slab waveguide having a coupling surface to which the first slab waveguide is coupled, a plurality of arrayed waveguides connected to the first slab waveguide, and a second slab waveguide connected to a plurality of the arrayed waveguides, the first slab waveguide having a coupling surface in a space outside the optical waveguide substrate in a top view, Light receiving element or light emitting element The end surface of the insulating film 10 is disposed so as to intersect with the end surface of the insulating film 10 facing the insulating film 1.

[0012] According to one embodiment of the present disclosure, there is provided an optical module mounting method for mounting an optical module comprising: an optical waveguide substrate including an arrayed waveguide grating; and an optical element that couples an optical signal to the arrayed waveguide grating, the arrayed waveguide grating including a first slab waveguide having a coupling surface to which light of the optical element is coupled, a plurality of arrayed waveguides connected to the first slab waveguide, and a second slab waveguide connected to the arrayed waveguide, the first slab waveguide having at least a part of the coupling surface in contact with an end surface of the optical waveguide substrate facing the optical element, or the coupling surface is in a space outside the optical waveguide substrate and is disposed so as to intersect with the end surface, the method comprising the steps of: measuring an oscillation wavelength of the optical element; measuring a transmission wavelength of the arrayed waveguide grating; and deriving a mounting position of the optical element based on the oscillation wavelength and the transmission wavelength.

[0013] According to the above-mentioned embodiment, it is possible to provide an optical module and a mounting method thereof, which use a planar lightwave circuit type filter, and which is advantageous in terms of reducing the number of parts, miniaturizing the device, simplifying the mounting process, and improving the manufacturing yield, and which can adjust the oscillation wavelength and the transmission wavelength with high precision. In addition, since the oscillation wavelength and the transmission wavelength can be adjusted during the mounting process, it is possible to improve the yield of parts and the optical characteristics of the module. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a diagram for explaining a known optical module. [Diagram 2] FIG. 2 is a diagram for explaining an optical module according to a first embodiment of the present disclosure. [Diagram 3] 3A is an enlarged top view of the area indicated by the dashed line in FIG. 2, and FIG. 3B is a cross-sectional view taken along the arrow indicated in FIG. [Figure 4] FIG. 1A is a top view of a region including a slab waveguide of another configuration of the first embodiment, and FIG. 1B is a cross-sectional view taken along the arrow shown in FIG. [Diagram 5]1A is a diagram for explaining a mounting method of the optical module according to the first embodiment, and FIG. 1B is a cross-sectional view taken along the arrow shown in FIG. [Figure 6] FIG. 13(a) is a top view showing a region including a slab waveguide of a second embodiment, and (b) is a cross-sectional view taken along the arrow in (a). [Figure 7] FIG. 13(a) is a top view showing a region including a slab waveguide of a third embodiment, and (b) is a cross-sectional view taken along the arrow in (a). [Figure 8] FIG. 13(a) is a top view showing a region including a slab waveguide of a fourth embodiment, and (b) is a cross-sectional view taken along the arrow in (a). [Figure 9] FIG. 13(a) is a top view showing a region including a slab waveguide of a fifth embodiment, and (b) is a cross-sectional view taken along the arrow in (a). [Figure 10] FIG. 13(a) is a top view showing a region including a slab waveguide of a sixth embodiment, and (b) is a cross-sectional view taken along the arrow in (a). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] [First embodiment] Hereinafter, the first to sixth embodiments of the present disclosure will be described. The drawings used in the first to sixth embodiments are intended to explain the technical ideas, configurations, relationships, actions, effects, and functions of the present disclosure, and do not limit the configuration or shape of the present disclosure. For this reason, the scale, aspect ratio, thickness, height, width, and the like shown in the drawings are not necessarily accurate, and some parts may be enlarged or omitted for the purpose of explanation. In addition, in the drawings of the present embodiment, the same symbols are attached to the same parts, and their explanations may be partially omitted.

[0016] (Optical module) FIG. 2 is a diagram for explaining an optical module 10 according to a first embodiment of the present disclosure, and is a top view of the optical module 10. The optical module 10 is configured as an optical transmission module, and is a planar lightwave circuit type filter using an optical waveguide substrate 12 made of quartz. In the coordinate system shown in FIG. 2, the first embodiment will be described below with the Z axis as the input / output direction of light, the X axis as the direction perpendicular to the input / output direction of light, and the Y axis as the direction perpendicular to the main surface (XZ plane) of the optical waveguide substrate 12. The planar lightwave circuit type filter in the first embodiment includes an optical waveguide substrate 12 and an arrayed waveguide grating formed in the optical waveguide substrate 12, and the arrayed waveguide grating includes an arrayed waveguide group 19 including slab waveguides 14a (first slab waveguide) and 14b (second slab waveguide), a plurality of arrayed waveguides 19a connected to the slab waveguides 14a and 14b, and an output waveguide 13 connected to the slab waveguide 14b.

[0017] The optical module 10 also has laser diodes 11a, 11b, 11c, and 11d, which are optical elements, and the laser diodes 11a, 11b, 11c, and 11d each output laser light of a different wavelength. In the first embodiment, when there is no need to distinguish between the laser diodes, they will be simply referred to as laser diodes 11. In the first embodiment, an InP laser chip is used for the laser diode 11, but the material of the laser chip is arbitrary. The laser light from each laser diode 11 is coupled to the input side slab waveguide 14a of the arrayed waveguide grating. The slab waveguide 14a has an end face 14ab connected to the arrayed waveguide 19a and a coupling face 14aa on the side where the light is coupled. The laser light incident on the slab waveguide 14a from the end face of the planar lightwave circuit chip is coupled to the arrayed waveguide 19a at the end face 14ab, passes through the arrayed waveguide 19a and enters the slab waveguide 14b, is collected in the slab waveguide portion 14b, and is coupled to the output waveguide 13 and then coupled to the fiber 23 via the lenses 15 and 17 and the isolator 16.

[0018] In the first embodiment, a laser diode 11 is provided separated from the arrayed waveguide grating by a space, and a cylindrical lens 20 is provided in the space between the laser diode 11 and the slab waveguide 14a. Therefore, the laser light output from the laser diode 11 passes through the space and the cylindrical lens 20, is input to the coupling surface 14aa of the slab waveguide 14a, and is then coupled to the arrayed waveguide at another pair of slab end surfaces 14ab.

[0019] The optical module 10 also includes lenses 15, 17 and an isolator 16 for coupling the laser light from the optical module 10 to the fiber 18. The lens 15 and the isolator 16 are provided inside the ceramic package 25, and the lens 17 is provided outside the ceramic package 25. The lenses 15, 17 are a pair of collimating lenses that collimate the laser light output from the output waveguide 13 into a parallel light beam. The isolator 16 is disposed between the lenses 15, 17. The fiber 18 is protected by a resin member 23. The laser light enters the arrayed waveguide 19a from the free space of the slab waveguide 14a. The lengths of the arrayed waveguides 19a differ by ΔL. The laser light that has passed through the arrayed waveguide 19a enters the output waveguide 13 from the slab waveguide 14b and interferes so that only a specific wavelength is output. The laser light is then focused on the fiber 18 by the lenses 15, 17 and output from the ceramic package 25. Furthermore, the optical module 10 may also be equipped with a temperature controller (not shown), an RF circuit for driving the laser diode 11, a power meter for monitoring the power of the laser diode 11, and the like.

[0020] As described above, the arrayed waveguide grating includes a slab waveguide 14a having coupling surfaces 14aa and 14ab, a plurality of arrayed waveguides 19a connected to the slab waveguide 14a, and a slab waveguide 14b connected to the plurality of arrayed waveguides 19a. The slab waveguide 14a is arranged such that, in top view, at least a part of the coupling surface 14aa contacts the end surface 12a of the optical waveguide substrate 12 facing the laser diode 11, or the coupling surface 14aa is in the space outside the optical waveguide substrate 12 and intersects with the end surface 12a.

[0021] This configuration will be described in more detail with reference to Figures 3(a) and 3(b). Figure 3(a) is a top view showing an enlarged view of the area B shown by the dashed line in Figure 2, and Figure 3(b) is a cross-sectional view taken along the arrows IIIb and IIIb in Figure 3(a). As shown in Figure 3(b), the laser diode 11 is composed of a laser chip 28 and a subassembly 22. The multiple laser diodes 11 are arranged such that the central axes of the laser chips 28 form an angle with each other. Hereinafter, this state will also be referred to as the laser diodes 11 being radially arranged. The spot size of the laser light output from the laser chip 28 in a top view is ω LD , the spacing between the laser chips 28 is P LD As shown in Fig. 3(a), the slab waveguide 14a of the first embodiment is disposed so that its coupling surface 14aa is in the space outside the optical waveguide substrate 12 and intersects with the end surface 12a facing the laser diode 11 in a top view. As shown in Fig. 3(a), the slab waveguide 14a is disposed so that its coupling surface 14aa is a curved surface and the start and end points of the curve of the surface intersect with the end surface 12a. However, the degree of intersection between the slab waveguide 14a and the end surface 12a, that is, the degree to which the slab waveguide 14a is exposed from the optical waveguide substrate 12, is arbitrary.

[0022] By arranging the slab waveguide 14a so that the slab waveguide 14a intersects with the end face 12a, the first embodiment can bring the coupling surface 14aa close to the end face 12a and expose it from the end face 12a. With this configuration, the laser diode 11 is arranged sufficiently close to the coupling surface 14aa, and the laser light L p to the coupling surface 14aa. Furthermore, since the input waveguide 113a is not provided, a space for routing the input waveguide 113a is not required, so that the ceramic package 25 can be made smaller, and therefore the optical module 10 can be made smaller.

[0023] In the first embodiment, in which the input waveguide 113a is not required, the laser diode 11 is disposed with a space between it and the coupling surface 14aa, and the light from the laser diode 11 passes through the space, enters the slab from the coupling surface 14aa, and is coupled to the arrayed waveguide 19 at the coupling surface 14ab. p It is known that when coupling the laser light L to the coupling surface 14aa, the spot sizes of the laser chip 28 and the end face of the slab waveguide 14a are made equal to each other to reduce coupling loss. For this reason, in the first embodiment, a cylindrical lens 20 is provided between the laser diode 11 and the coupling surface 14aa, and the laser light L p The optical module 10 may adjust the spot size of the laser light L from the laser diode 11 having a large NA. p However, in the direction perpendicular to the main surface of the optical waveguide substrate 12 (Y direction in the figure), the laser light L p Therefore, in the first embodiment, the cylindrical lens 20 is used to focus the laser light L p Concentrate the power of in the Y-axis direction.

[0024] In the first embodiment described above, the lenses 111 and the input waveguide 113a shown in Fig. 1 are not required, so that it is possible to reduce the number of parts in the ceramic package 25 and to miniaturize the optical module 1. In particular, since the waveguide requires an installation space that does not cause bending loss, the effect of miniaturization achieved by omitting the waveguide is remarkable. In addition, since the assembly and alignment processes of the lenses 111 are not required, the cost associated with assembling and mounting the optical module 10 can be reduced, and the work can be simplified to increase the production yield.

[0025] The optical module 10 shown in Fig. 3(a) and Fig. 3(b) is manufactured, for example, by depositing an undercladding layer of about several tens of micrometers on a Si substrate, depositing a core layer of several micrometers with a different refractive index, forming an arrayed waveguide grating pattern by known exposure and etching techniques, and then depositing an overcladding layer of several tens of micrometers. In this case, when manufacturing a curved coupling surface 14aa as shown in Fig. 3(a), one end surface of the slab waveguide 14a is exposed by etching. Therefore, in the manufacturing process of the slab waveguide 14a shown in Fig. 3(a), it is necessary to add an etching process after forming the slab waveguide 14a.

[0026] 4(a) and 4(b) are diagrams for explaining a configuration in which the coupling surface 14aa is not exposed from the optical waveguide substrate. FIG. 4(a) is a top view of a region including the slab waveguide 14a in which the coupling surface 14aa is not exposed from the optical waveguide substrate 12, and FIG. 4(b) is a cross-sectional view taken along the arrows IV and IV in FIG. 4(a). As shown in FIG. 4(a), an example of such an optical module has a configuration in which the coupling surface 14aa of the slab waveguide 14a contacts the end face 12a. In the example shown in FIG. 4(a), the coupling surface 14aa is a curved surface, and the slab waveguide 14a is disposed so that a part of the coupling surface 14aa contacts the end face 12a.

[0027] It should be noted that the first embodiment is not limited to the configuration described above. For example, the optical element includes not only a light emitting element such as the laser diode 11 but also a light receiving element. An optical module using a light receiving element is configured to receive and output light that is coupled with the coupling surface of the slab waveguide. For example, a photodiode is used as the light receiving element. Also, the laser light L of the slab waveguide 14a is p The adjustment of the spot size is not limited to using the cylindrical lens 20, and may be performed using, for example, a spot size converter. The spot size converter may be provided near the output end of the laser light from the laser diode 11, near the end face of the arrayed waveguide grating on the input side of the laser light, or both. The material of the optical waveguide substrate 12 is not limited to quartz, and may be other materials such as a silicon photonics waveguide.

[0028] (Optical module mounting method) Next, a method for mounting the optical module of the first embodiment described above will be described. The mounting method of the first embodiment makes it possible to finely adjust the shift in the transmission wavelength of the arrayed waveguide grating by adjusting the mounting positions of the laser diode 11 and the optical module 10. When active operation is possible while injecting a current into the laser diode 11, the power of the laser light output from the fiber 18 is monitored, and the laser diode 11 is mounted at a position where the monitored power is maximum, that is, where the oscillation wavelength of the laser light and the transmission wavelength of the arrayed waveguide grating match.

[0029] Furthermore, if it is difficult to perform active alignment while injecting a current into the laser diode 11, mounting is performed by utilizing mounting marks formed on the optical module 10.

[0030] FIG. 5(a) is a top view showing the mounting mark of the optical module 10, and FIG. 5(b) is a cross-sectional view taken along the arrows Xb and Xb in FIG. 5(a). In this case, in order to evaluate the characteristics of the arrayed waveguide grating alone, the glass layer of the optical waveguide substrate 12 is removed by etching to form a removed region 95. The coupling surface 14aa of the slab waveguide 14a is exposed by etching the glass layer, and the laser diode 11 is mounted in the removed region 95. In addition, a marker 91 for aligning the laser diode 11 is formed in the removed region 95. However, the marker 91 may be formed on the optical waveguide substrate 12 where the glass layer has not been removed. By forming the marker 91 during the exposure process when forming the arrayed waveguide grating, the arrayed waveguide group 19 and the marker 91 can be aligned on the submicron order.

[0031] Next, the mounting process of the optical module 10 will be described. In the mounting process, first, the oscillation wavelength of each laser diode 11 and the transmission wavelength of the arrayed waveguide grating are measured in advance. The mounting position of the laser diode 11 is determined under the condition that both the oscillation wavelength and the transmission wavelength are consistent with the design wavelength. If the oscillation wavelength or the transmission wavelength is deviated from the design wavelength, the laser diode 11 is mounted by shifting the mounting position by the deviation from the design wavelength, using the marker 91 formed on the optical module 10 as a reference. With this method, the first embodiment can mount both the arrayed waveguide grating and the laser diode 11 so that their oscillation wavelengths match each other.

[0032] For example, when the transmission wavelength of the arrayed waveguide grating is shifted by Δλ from the design wavelength λ, the laser diode 11 is mounted shifted by Δα from the designed mounting position. In this case, for example, the marker 91 is formed in accordance with the designed mounting position, and the mounting position of the laser diode 11 is shifted by Δα with the marker 91 as the reference.

[0033] The relationship between the design wavelength λ, the wavelength deviation Δλ, and the mounting position deviation Δα is given by the following formula (1): In formula (1), Nc is the core refractive index of the arrayed waveguide grating, ns is the refractive index of the slab waveguide 14a, d is the spacing between the arrayed waveguides 19a (FIG. 2), ΔL is the waveguide length difference of the arrayed waveguide 19a, and f is the focal length of the slab waveguide 14a.

[0034]

number

[0035] Furthermore, the alignment of the laser diode 11 and the arrayed waveguide grating may be performed by oscillating the laser diode 11 using the electrode 92 for the laser diode 11 and attaching the inspection port 93 to the coupling surface 14aa. In such a case, the laser diode 11 is mounted at a position where the oscillation wavelength of the laser diode 11 and the transmission wavelength of the arrayed waveguide grating coincide with each other and the laser light output from the inspection port 93 is at a maximum value. The common port 94 is used to monitor the deviation of the transmission wavelength of the arrayed waveguide grating alone. According to the mounting method of the optical module of the first embodiment, the oscillation wavelength of the laser diode 11 can be adjusted to the transmission wavelength of the arrayed waveguide grating when the laser diode 11 is mounted, so that the transmission wavelength of the arrayed waveguide grating and the oscillation wavelength of the laser diode 11 can be adjusted with high accuracy. Moreover, the mounting method of the first embodiment can ease the requirements for the accuracy of the wavelength and the shape of the arrayed waveguide grating. This improves the manufacturing yield of the arrayed waveguide grating and the optical module.

[0036] The mounting process described above is a method for mounting the optical module 10 of the first embodiment described in Fig. 2 to Fig. 4(b). The mounting method of the first embodiment includes a step of measuring the oscillation wavelength of the laser diode 11, a step of measuring the transmission wavelength of the arrayed waveguide grating, and a step of deriving the mounting position of the laser diode 11 based on the oscillation wavelength and the transmission wavelength. Such a mounting method can be performed automatically and collectively by using, for example, an apparatus including a wavelength measuring unit that measures the oscillation wavelength and the transmission wavelength, and a computer that calculates the deviation amount between the designed wavelengths of both, and calculates the difference between the designed mounting position and the actual mounting position.

[0037] Moreover, the mounting method of the first embodiment further includes a step of mounting the laser diode 11 at the mounting position derived in the deriving step. Such a step may be automatically performed by combining the device having the computer with a robot hand, a manipulator, or the like.

[0038] [Second embodiment] Next, a second embodiment of the present disclosure will be described. The second embodiment differs from the first embodiment in that not only the end face of the slab waveguide 14a but also a larger portion thereof is exposed from the optical waveguide substrate 12. FIG. 6(a) is a top view showing a region including a slab waveguide 54 of the second embodiment, and FIG. 6(b) is a cross-sectional view taken along the arrows Vb, Vb in FIG. 6(a). As shown in FIG. 6(a), the slab waveguide 54 is exposed from the optical waveguide substrate 12 up to the vicinity of the arrayed waveguide group 19, whereas the configuration shown in FIG. 3(a) of the first embodiment exposes the end face of the slab waveguide 14a from the optical waveguide substrate 12. In this second embodiment, the laser light L shown in FIG. 6(b) is also exposed from the optical waveguide substrate 12. p The slab waveguide 54 is disposed so that a coupling surface 54a where the light is coupled contacts the end surface 12a. The end surface of the slab waveguide 54 opposite the coupling surface 54a is referred to as an end surface 54b.

[0039] The second embodiment can be realized by forming the slab waveguide 14a, the arrayed waveguide 19a, the slab waveguide 14b, and the output waveguide 13 in the optical waveguide substrate 12, and then etching more portions than in the first embodiment, as in the first embodiment. The slab waveguide 14a is processed into the slab waveguide 54 by etching. In the second embodiment, the length of the slab waveguide 54 in the Z-axis direction is further shortened, which is more advantageous for miniaturizing the optical module. Also in the second embodiment, a cylindrical lens 20 or a spot size converter (not shown) may be provided to adjust the spot size of the laser diode 11 and the spot size of the slab waveguide 14a.

[0040] [Third embodiment] Next, a third embodiment of the present disclosure will be described. Figures 7(a) and (b) are diagrams for explaining the third embodiment, where Figure 7(a) is a top view showing a region including the slab waveguide 14a of the third embodiment, and Figure 7(b) is a cross-sectional view along the arrows VIb and VIb in Figure 7(a). The third embodiment is different from the first embodiment in that the laser diode 11 is disposed farther away from the coupling surface 14aa than in the first embodiment, and a plurality of lenses 61 are provided between the laser diode 11 and the cylindrical lens 20. The plurality of laser diodes 11 are radially disposed, and the coupling surface 14aa is a curved surface. The plurality of lenses 61 are disposed corresponding to each of the laser diodes 11. The lens 61 converts the light of the corresponding laser diode 11 into collimated light. The collimated light is collected in the Y direction by the cylindrical lens 20 and coupled to the coupling surface 14aa.

[0041] Here, the effects of arranging the laser diode 11 farther away from the coupling surface 14aa than in the first embodiment will be described. One of the effects is that the degree of freedom in arranging the laser diode 11 is increased. For example, if it is necessary to arrange the laser diodes 11 with intervals due to electrical wiring or the like, it becomes impossible to arrange the laser diodes 11 within the range of the width of the slab waveguide 14a in the X direction. To solve this problem, in the third embodiment, the laser light that spreads beyond the width of the slab waveguide 14a is collimated by a lens 61 into a collimated light L pp and then coupled to the coupling surface 14aa. In the third embodiment, the laser light is coupled to the coupling surface 14aa via the lens 61, so that the interval between the incidence positions 14ap of the multiple laser lights can be narrowed, and the focal length f1 of the input waveguide can be shortened, thereby shortening the length of the slab waveguide 14a in the Z direction. This is advantageous for miniaturizing the optical module 10.

[0042] [Fourth embodiment] Next, a fourth embodiment of the present disclosure will be described. The fourth embodiment differs from the third embodiment in that the laser diodes 11 are arranged in parallel to each other, in that the laser diodes 11 are arranged radially. The fourth embodiment also differs from the third embodiment in that the coupling surface 14ca of the slab waveguide 14c is a flat surface. Such a fourth embodiment is effective in cases where it is difficult to arrange the laser diodes 11 radially due to electrical wiring and the like, and where it is necessary to avoid the complication of the structure caused by exposing the coupling surface of the slab waveguide.

[0043] 8(a) and 8(b) are diagrams for explaining the fourth embodiment, in which FIG. 8(a) is a top view showing a region including the slab waveguide 14c of the fourth embodiment, and FIG. 8(b) is a cross-sectional view taken along the arrows VIIb and VIIb in FIG. 8(a). In the fourth embodiment, the laser diode 11 is disposed farther away from the arrayed waveguide grating than in the third embodiment. In the example shown in FIG. 8(a) and FIG. 8(b), the laser diode 11 is disposed outside the Si substrate 21 that supports the optical waveguide substrate 12. The optical module of the fourth embodiment includes a plurality of lenses 61 disposed corresponding to each of the plurality of laser diodes 11, as in the third embodiment. However, the lenses 61 of the fourth embodiment are disposed on a straight line along the X-axis in the figure. In addition, the optical module of the fourth embodiment includes a cylindrical lens 20 between the lens 61 and the arrayed waveguide grating, which focuses the laser light in the Y direction. In the fourth embodiment, the position of each lens 61 is set to be parallel to the center line P of the corresponding laser diode 11 in the X direction. x By shifting the beam in the -X direction from pp The traveling direction of the laser beam is bent, and all the laser beams are focused at one point on the coupling surface 14ca of the slab waveguide 14c. In the fourth embodiment, as shown in Fig. 8(b), the distance from the laser diode 11 to the lens 61 and the distance from the lens 61 to the end face of the optical waveguide substrate 12 are both focal length f1. According to the fourth embodiment, even if the laser diode 11 is disposed so that the optical axis is parallel to the Z axis in the figure, it is possible to focus the laser beam at an appropriate focal length.

[0044] [Fifth embodiment] Next, a fifth embodiment of the present disclosure will be described. The fifth embodiment is different in that the fourth embodiment includes a plurality of lenses 61 corresponding to the laser diodes 11, whereas the fifth embodiment includes one lens 81. FIGS. 9(a) and 9(b) are diagrams for explaining the fifth embodiment, in which FIG. 9(a) is a top view showing a region including the slab waveguide 14c of the fifth embodiment, and FIG. 9(b) is a cross-sectional view taken along the arrows VIIIb and VIIIb in FIG. 9(a). The lens 81 of the fifth embodiment transmits all the laser beams output from the plurality of laser diodes 11 between the laser diode 11 and the cylindrical lens 20. The cylindrical lens is disposed so as to be in contact with the end face of the optical waveguide substrate 12, and focuses the laser beam in the Y direction in the figure. The spot size in the X direction of the laser beam coupled to the coupling surface 14ca is indicated by ω in the figure. LD It is written as follows.

[0045] According to the fifth embodiment, since the plurality of lenses 61 are replaced with one lens, it is possible to reduce the number of parts of the optical module, relax the assembly precision requirements, and avoid a complicated structure.

[0046] Sixth embodiment Next, a sixth embodiment of the present disclosure will be described. The sixth embodiment differs from the fifth embodiment in that the slab waveguide 54 of the second embodiment is provided instead of the slab waveguide 14c of the fifth embodiment. Figures 10(a) and (b) are diagrams for explaining the sixth embodiment, where Figure 10(a) is a top view showing a region including the slab waveguide 54 of the sixth embodiment, and Figure 10(b) is a cross-sectional view taken along the arrows IXb and IXb in Figure 10(a). The laser diodes 11 are arranged parallel to each other, and the laser light is collimated by a lens 81 into a collimated light L pp A cylindrical lens 20 is disposed between the lens 81 and the slab waveguide 54 to focus the laser light in the Y direction. The laser light is focused at different positions on the linear coupling surface 54a.

[0047] In the fourth and fifth embodiments, the distance from the laser diode 11 to the arrayed waveguide grating was twice the focal length f1. However, in the sixth embodiment, the distance from the laser diode 11 to the lens 81 is shortened, so that the distance from the laser diode 11 to the arrayed waveguide grating is set to the focal length f1. In the sixth embodiment, the laser light is made incident in a widened state on the end face behind the coupling surface 54a of the slab waveguide 54, thereby making the focal length shorter than in the fourth and fifth embodiments in which the laser light is widened and then focused to be incident on the slab waveguide 14c, and this is advantageous in terms of miniaturizing the optical module. [Explanation of symbols]

[0048] 10,100 Optical Modules 11 Laser Diode 12 Optical waveguide substrate 12a End face 13 Output waveguide 14a, 14b, 14c, 54 Slab waveguide 14aa, 14ca, 54a bonding surface 14ap incident position 15, 17, 61, 81 Lenses 16 Isolator 18 Fiber 19 Arrayed Waveguide 19a Arrayed Waveguide 20 Cylindrical Lens 21. Silicon substrate 22 Subassembly 23 Resin parts 25 Ceramic Package 26 Support part 28 Laser Chip 91 Marker 92 electrodes 93 Inspection Port 95 Removal area

Claims

1. An optical module comprising: an optical waveguide substrate having an arrayed-waveguide grating; and a light-emitting element for outputting an optical signal to the arrayed-waveguide grating or a light-receiving element for inputting an optical signal from the arrayed-waveguide grating, an optical module, wherein the arrayed waveguide diffraction grating includes a first slab waveguide having a coupling surface to which the optical signal is coupled, a plurality of arrayed waveguides connected to the first slab waveguide, and a second slab waveguide connected to a plurality of the arrayed waveguides, the first slab waveguide being disposed such that, in a top view, the coupling surface is in a space external to the optical waveguide substrate and intersects with an end face of the optical waveguide substrate facing the light receiving element or the light emitting element.

2. The optical module according to claim 1 , wherein the light receiving element or the light emitting element is disposed across a space from the coupling surface, and the optical signal is coupled to the coupling surface through the space.

3. a spot size adjusting unit disposed between the arrayed waveguide grating and the light receiving element or the light emitting element, the spot size adjusting unit adjusting a spot size of an end face of the arrayed waveguide grating, or of the light receiving element or the light emitting element; 3. The optical module according to claim 1, wherein the spot size adjuster includes at least one of a cylindrical lens and a spot size converter that condenses light in a direction perpendicular to a main surface of the optical waveguide substrate.

4. 4. The optical module according to claim 1, further comprising a lens disposed between the arrayed waveguide grating and the light receiving element or the light emitting element, for converting the optical signal into collimated light.

5. 1. A method for mounting an optical module comprising: an optical waveguide substrate having an arrayed waveguide grating; and an optical element for coupling an optical signal to the arrayed waveguide grating, the arrayed waveguide grating including a first slab waveguide having a coupling surface to which light of the optical element is coupled, a plurality of arrayed waveguides connected to the first slab waveguide, and a second slab waveguide connected to the arrayed waveguide, the first slab waveguide being disposed such that, in a top view, at least a part of the coupling surface is in contact with an end surface of the optical waveguide substrate facing the optical element, or the coupling surface is in a space outside the optical waveguide substrate and intersects with the end surface, measuring an oscillation wavelength of the optical element; measuring a transmission wavelength of the arrayed waveguide grating; and deriving a mounting position of the optical element based on the oscillation wavelength and the transmission wavelength.

6. 6. The method for mounting an optical module according to claim 5, further comprising the step of mounting the optical element at the mounting position derived in the step of deriving the mounting position.

7. 7. The method for mounting an optical module according to claim 6, wherein a marker formed on the optical module is used in the step of mounting the optical element.

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