WO2023095224A1

WO2023095224A1 - Optical module and optical module mounting method

Info

Publication number: WO2023095224A1
Application number: PCT/JP2021/043084
Authority: WO
Inventors: 藍柳原; 賢哉鈴木; 慶太山口; 慈金澤
Original assignee: 日本電信電話株式会社
Priority date: 2021-11-24
Filing date: 2021-11-24
Publication date: 2023-06-01
Also published as: JPWO2023095224A1

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

Optical module and mounting method of optical module

The present invention relates to an optical module and an optical module mounting method.

With the increasing speed and capacity of data communication, optical communication devices and optical interconnection technology are becoming more sophisticated. In optical communication devices, rather than using conventional single-function optical devices such as laser diodes (LDs), photodiodes (PDs), and optical waveguide filters, these multiple elements are combined. There is an increasing need for multi-channel, multi-function, high-performance integrated modules housed in a single package. In addition, there is a demand for miniaturization and cost reduction for these modules.

FIG. 1 is a diagram for explaining a known optical module, showing the upper surface of an optical transmission module 100. FIG. The optical transmission module 100 includes a plurality of laser diodes 110a to 110d with different wavelengths, a planar light wave circuit (PLC) filter 112 for combining the laser beams, and a planar light wave circuit filter 112. and a plurality of lenses 111 for condensing laser light, which are housed in a package 150 . The planar lightwave circuit filter 112 is arranged between an input waveguide 113a to which laser light is input, an output waveguide 113b to which the laser light input to the waveguide is output, and between the input waveguide 113a and the output waveguide 113b. and

slab waveguides

114 a and 114 b provided at both ends of the arrayed waveguide 119 .

Light output from the laser diodes 110a to 110d passes through the lens 111 to convert the beam diameter of the laser light and is coupled to the input waveguide 113a. Also, the light multiplexed through the arrayed waveguide is emitted from the output waveguide 113b and coupled to the optical fiber 118 through the

lenses

115 and 117, the isolator 116, and the like. In addition, although not shown, the optical transmission module 100 includes an electric circuit for driving and controlling the laser diode, a temperature controller, and the like.

Such planar lightwave circuit filters are described in Non-Patent Document 1 and Non-Patent Document 2, for example. Non-Patent Document 1 and Non-Patent Document 2 both aim to reduce the size of the optical assembly, and Patent Document 1 uses a TFF (thin film filter) that utilizes multilayer film reflection instead of a planar lightwave circuit type filter. configuration is described. In FIG. 1, a configuration in which four laser diodes are integrated was explained, but when the number of integrated laser diodes is further increased, a planar lightwave circuit type filter is used rather than a TFF from the viewpoint of reducing variations in optical characteristics and downsizing. It is more advantageous to have a Non-Patent Document 2 describes an arrayed waveguide grating as a planar lightwave circuit filter. A Demux (Demultiplexer) circuit using an arrayed waveguide grating consists of a plurality of input waveguides, slab waveguides, arrayed waveguides, slab waveguides and output waveguides. It is coupled to the waveguide end face of the lightwave circuit. Optical semiconductors and waveguides of planar lightwave circuits have large numerical apertures (NA), making low-loss connections difficult. SSCs (Spot Size Converters) are introduced into bulk lenses, optical semiconductors, and quartz PLC waveguide end faces. .

In the example of the optical transmission module 100 shown in FIG. 1, for example, laser light output from one laser diode 110a is collimated by two

lenses

111, 111 and condensed into an input waveguide 113a. However, the configuration of the optical coupling portion A, which is the portion (indicated by the dashed line) between the laser diode 111 and the input waveguide 113a, is not limited to the example shown in FIG. , or alternatively, a configuration including three lenses is conceivable.

However, in the optical coupling section A, if only one lens is used to focus the laser light onto the input waveguide in order to reduce the size of the package, the tolerance for component mounting misalignment becomes severe, and mounting difficulty increases. As a result, it is difficult to improve the manufacturing yield of optical modules. Moreover, if the number of lenses is increased, the space for installing the lens components in the package of the optical module becomes large, which hinders miniaturization. Moreover, since the number of parts increases, the parts cost, the mounting cost, and the mounting process also increase, which is disadvantageous for cost reduction. Furthermore, the configuration using an optical waveguide for inputting laser light to the planar lightwave circuit type filter 112 requires a space for routing from the input waveguide 113a to the slab waveguide 114a so as not to cause bending loss. This point is also disadvantageous for miniaturization of the optical module.

In recent years, the wavelength interval of the integrated laser light has become narrower. Along with this, a high precision of the oscillation wavelength of the laser diode has been required. Also, regarding the filter characteristics of arrayed waveguides, there is a demand for high accuracy of transmission wavelength and highly rectangular filter characteristics. If the oscillation wavelength of the laser diode and the transmission wavelength of the arrayed waveguide deviate from the design, the optical characteristics of the multiplexed waves will deteriorate. It's becoming It is conceivable that the central wavelengths of the laser and the filter are shifted due to manufacturing errors. Therefore, in the future, there will be a demand for higher precision in the oscillation wavelength and filter characteristics of laser diodes, and along with the expansion of the signal band, the tolerance between the oscillation wavelength of laser diodes and the transmission wavelength of arrayed waveguide diffraction gratings will become stricter. ing. For this reason, optical modules are required to have high-precision control of filter wavelengths and high-precision control of laser diode oscillation wavelengths in wavelength division multiplexing communications. However, miniaturization of optical modules has made assembly and alignment of laser diodes and arrayed waveguide diffraction gratings more sophisticated, making it difficult to precisely match the oscillation wavelength and the transmission wavelength.

The present invention has been made in view of the above points, and is advantageous in reducing the number of parts, miniaturizing, simplifying the mounting process, and improving the manufacturing yield by using a planar lightwave circuit type filter. An optical module capable of adjusting the oscillation wavelength and the 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, and a mounting method thereof. Regarding.

To achieve the above object, an optical module according to one aspect of the present disclosure is an optical module having 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 diffraction grating includes a first slab waveguide having a coupling surface to which light from the optical element is coupled, a plurality of arrayed waveguides connected to the first slab waveguide, and a plurality of a second slab waveguide connected to the arrayed waveguide, wherein the first slab waveguide has at least a portion of the coupling surface facing the optical element of the optical waveguide substrate when viewed from the top. They are in contact with each other, or arranged such that the coupling surface is in a space outside the optical waveguide substrate and intersects with the end surface.

An optical module mounting method according to one embodiment of the present disclosure includes an optical waveguide substrate including an arrayed waveguide grating, and an optical element that couples an optical signal to the arrayed waveguide grating. is a first slab waveguide having a coupling surface to which light from 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; At least a portion of the coupling surface of the first slab waveguide is in contact with an end surface of the optical waveguide substrate facing the optical element, or the coupling surface extends outside the optical waveguide substrate when viewed from above. 3, an optical module mounting method for mounting an optical module arranged to intersect with the end surface, the method comprising: measuring an oscillation wavelength of the optical element; and transmitting a wavelength of the arrayed waveguide diffraction grating. and deriving the mounting position of the optical element based on the oscillation wavelength and the transmission wavelength.

According to the above embodiment, the planar lightwave circuit type filter is used, which is advantageous in reducing the number of parts, reducing the size, simplifying the mounting process, and improving the manufacturing yield. A tunable optical module and a mounting method thereof can be provided. In addition, since the transmission wavelength and the transmission wavelength can be matched during the mounting process, it is possible to improve the yield of parts and the optical characteristics of the module.

It is a figure for demonstrating a well-known optical module. 1 is a diagram for explaining an optical module according to a first embodiment of the present disclosure; FIG. (a) is a top view showing an enlarged range indicated by broken lines in FIG. 2, and (b) is a cross-sectional view taken along the arrow shown in (a). (a) is a top view of a region including a slab waveguide having another configuration according to the first embodiment, and (b) is a cross-sectional view taken along the arrow shown in (a). (a) is a diagram for explaining a mounting method of the optical module of the first embodiment. (b) is a cross-sectional view along the arrow shown in (a). (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). (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). (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). (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). (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).

[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 for the purpose of explaining the technical idea, configuration, relationship of each member, action, effect, and function of the present disclosure, and do not limit the configuration and shape of the present disclosure. . Therefore, the scales, aspect ratios, thicknesses, heights, widths, etc. shown in the drawings are not necessarily accurate, and may be partly enlarged or partly omitted for the sake of explanation. Also, in the drawings of the present embodiment, the same members are denoted by the same reference numerals, and the description thereof may be partly omitted.

(optical module)
FIG. 2 is a diagram for explaining the optical module 10 according to the first embodiment of the present disclosure, and is a top view of the optical module 10. FIG. 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, in the first embodiment, hereinafter, the Z axis is the light input/output direction, the X axis is the direction orthogonal to the light input/output direction, and the Y axis is the main surface of the optical waveguide substrate 12 ( XZ plane). The planar lightwave circuit filter referred to in the first embodiment includes an optical waveguide substrate 12 and an arrayed waveguide diffraction grating formed on the optical waveguide substrate 12. The arrayed waveguide diffraction grating includes a slab waveguide 14a (first slab waveguide), 14b (second slab waveguide), an arrayed waveguide group 19 composed of a plurality of arrayed waveguides 19a connected to the

slab waveguides

14a and 14b, and an output waveguide connected to the slab waveguide 14b. Including 13.

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 output laser beams of different wavelengths. In the first embodiment, hereinafter, the laser diodes 11 are simply referred to when there is no need to distinguish between the laser diodes. Although an InP laser chip is used for the laser diode 11 in the first embodiment, any material can be used for the laser chip. Laser light from each laser diode 11 is coupled to an input-side slab waveguide 14a of the arrayed waveguide grating. The slab waveguide 14a has an end surface 14ab connected to the arrayed waveguide 19a and a coupling surface 14aa on the light coupling side. A laser beam incident on the slab waveguide 14a from the end surface of the planar lightwave circuit chip is coupled to the arrayed waveguide 19a at the end surface 14ab, passes through the arrayed waveguide 19a, enters the slab waveguide 14b, and is collected at the slab waveguide portion 14b. The light is then coupled into output waveguide 13 and through

lenses

15 , 17 and isolator 16 into fiber 23 .

In the first embodiment, the laser diode 11 is provided with a space from the arrayed waveguide diffraction grating, and the 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.

The optical module 10 also includes

lenses

15 and 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 contained in the ceramic package 25, and the lens 17 outside the

Lenses

15 and 17 are a pair of collimating lenses that collimate the laser beam output from output waveguide 13 into parallel beams. The isolator 16 is arranged between the

lenses

15,17. Fiber 18 is protected by resin member 23 . Laser light enters the arrayed waveguide 19a from the free space of the slab waveguide 14a. The lengths of the arrayed waveguides 19a are different by ΔL. After passing through the arrayed waveguide 19a, the laser light is input from the slab waveguide 14b to the output waveguide 13, and interferes so that only a specific wavelength is output. The laser light is then condensed into the fiber 18 by the

lenses

15 and 17 and output from the ceramic package 25 . Furthermore, the optical module 10 may be mounted together 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.

As described above, the arrayed waveguide diffraction grating is connected to the slab waveguide 14a having the coupling surfaces 14aa and 14ab, the plurality of arrayed waveguides 19a connected to the slab waveguide 14a, and the plurality of arrayed waveguides 19a. It includes a slab waveguide 14b. In the slab waveguide 14a, when viewed from above, at least a part of the coupling surface 14aa is in contact with 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 is arranged to intersect with the end surface 12a.

Such a configuration will be described in more detail with reference to FIGS. 3(a) and 3(b). FIG. 3(a) is a top view showing an enlarged range B indicated by a dashed line in FIG. 2, and FIG. 3(b) is a sectional view taken along arrows IIIb and IIIb shown in FIG. 3(a). As shown in FIG. 3B, the laser diode 11 is composed of a laser chip 28 and a subassembly 22. As shown in FIG. The plurality of laser diodes 11 are arranged such that the central axes of the laser chips 28 form an angle with each other. Such a state is hereinafter also referred to as the laser diodes 11 being arranged radially. The spot size of the laser light output from the laser chip 28 when viewed from above is ω _LD , and the interval between the laser chips 28 is P _LD . As shown in FIG. 3A, in the slab waveguide 14a of the first embodiment, the coupling surface 14aa is located in the space outside the optical waveguide substrate 12 and intersects the end surface 12a facing the laser diode 11 when viewed from above. are arranged to As shown in FIG. 3A, the slab waveguide 14a has a curved coupling surface 14aa, and is arranged so that the start and end points of the curve on the surface intersect the end surface 12a. However, the degree of intersection between the slab waveguide 14a and the end face 12a, that is, the extent to which the slab waveguide 14a is exposed from the optical waveguide substrate 12 is arbitrary.

By arranging the slab waveguide 14a so that the slab waveguide 14a intersects the end face 12a, the first embodiment can bring the coupling surface 14aa closer to the end face 12a and expose it from the end face 12a. According to such a configuration, the laser diode 11 can be arranged sufficiently close to the coupling surface 14aa, and the laser light _Lp can be input to the coupling surface 14aa without providing the input waveguide 113a shown in FIG. Become. Since the input waveguide 113a is not provided, a space for routing the input waveguide 113a is not required, and the ceramic package 25 can be miniaturized, and the optical module 10 can be miniaturized.

In the first embodiment, which does not require the input waveguide 113a, the laser diode 11 is spaced apart from the coupling surface 14aa, and the light from the laser diode 11 passes through the space and enters the slab from the coupling surface 14aa. It is coupled to the arrayed waveguide 19 at the coupling surface 14ab. In the optical module 10, when the laser light _Lp output from the laser diode 11 is coupled to the coupling surface 14aa, the spot size of the laser chip 28 and the end surface of the slab waveguide 14a can be matched to reduce the coupling loss. Are known. Therefore, in the first embodiment, a cylindrical lens 20 may be provided between the laser diode 11 and the coupling surface 14aa to adjust the spot size of the laser light _Lp . Such an optical module 10 is configured to receive laser light _Lp from a laser diode 11 with a large NA by an array waveguide with a large aperture. However, in the direction perpendicular to the main surface of the optical waveguide substrate 12 (the Y direction in the figure), it is possible to reduce the optical loss by condensing the laser light _Lp . Therefore, in the first embodiment, the cylindrical lens 20 is used to concentrate the power of the laser light _Lp in the Y-axis direction.

The first embodiment described above eliminates the need for the plurality of lenses 111 and the input waveguide 113a shown in FIG. Become. In particular, since a waveguide requires an installation space that does not cause bending loss, the effect of size reduction by omitting the waveguide is remarkable. In addition, since the process of assembling and aligning the plurality of lenses 111 is unnecessary, the cost of assembling and mounting the optical module 10 can be reduced, the work can be facilitated, and the production yield can be increased.

The optical module 10 shown in FIGS. 3(a) and 3(b) is formed by, for example, depositing an under-cladding layer of about several tens of μm on a Si substrate, depositing a core layer of several μm with a different refractive index, and performing a known exposure method. It is manufactured by forming the pattern of the arrayed waveguide grating by an etching technique and then depositing an overcladding layer of several tens of μm. At this time, when manufacturing a curved coupling surface 14aa as shown in FIG. 3A, 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. 3A, it is necessary to add an etching process after forming the slab waveguide 14a.

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 where the coupling surface 14aa is not exposed from the optical waveguide substrate 12, and FIG. It is a sectional view. As shown in FIG. 4A, an example of such an optical module has a configuration in which a coupling surface 14aa of a slab waveguide 14a is in contact with an end surface 12a. Further, in the example shown in FIG. 4A, the coupling surface 14aa is a curved surface, and the slab waveguide 14a is arranged so that a part of the coupling surface 14aa is in contact with the end surface 12a.

In addition, 1st Embodiment is not limited to the structure demonstrated above. For example, optical elements include not only light-emitting elements such as the laser diode 11 but also light-receiving elements. An optical module using a light receiving element is configured to receive and output light coupled with a coupling surface of a slab waveguide. For example, a photodiode is used as the light receiving element. Further, adjustment of the spot size of the laser light _Lp in the slab waveguide 14a is not limited to using the cylindrical lens 20, and for example, a spot size converter may be used. The spot size converter may be provided near the laser light output end of the laser diode 11, near the laser light input side facet of the arrayed waveguide grating, or both. The optical waveguide substrate 12 is not limited to being made of quartz, and may be made of other materials such as a silicon photonics waveguide.

(Mounting method of optical module)
Next, a method for mounting the optical module of the first embodiment described above will be described. The mounting method of the first embodiment can finely adjust the transmission wavelength shift 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 position where the monitored power takes the maximum value, that is, the oscillation wavelength of the laser light and the array A laser diode 11 is mounted at a position where the transmission wavelengths of the waveguide grating match.

Also, if active alignment while injecting current into the laser diode 11 is difficult, mounting is performed using mounting marks formed on the optical module 10 .

FIG. 5(a) is a top view showing mounting marks for the optical module 10, and FIG. 5(b) is a cross-sectional view taken along arrows Xb and Xb in FIG. 5(a). In such a case, in order to evaluate the characteristics of the single arrayed waveguide diffraction grating, the glass layer of the optical waveguide substrate 12 is removed by etching to form a removed region 95 . The etching of the glass layer exposes the coupling surface 14aa of the slab waveguide 14a and mounts the laser diode 11 in the removed area 95. FIG. A marker 91 for alignment of the laser diode 11 is formed in the removed region 95 . However, the marker 91 may be formed on the optical waveguide substrate 12 from which the glass layer has not been removed. By creating the markers 91 during the exposure process when creating the arrayed waveguide diffraction grating, the arrayed waveguide group 19 and the markers 91 can be aligned on the order of submicrons.

Next, the process of mounting 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 diffraction 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 match the design wavelength. When the oscillation wavelength or transmission wavelength deviates from the design wavelength, the laser diode 11 is mounted with the mounting position shifted by the deviation from the design wavelength with reference to the marker 91 formed on the optical module 10. . With such a method, the first embodiment can be implemented so that the oscillation wavelength of the arrayed waveguide grating and the transmission wavelength of the laser diode 11 match.

For example, if the transmission wavelength of the arrayed waveguide diffraction grating is shifted by Δλ from the design wavelength λ, the laser diode 11 is mounted with a shift of Δα from the design mounting position. At this time, for example, the marker 91 may be formed in accordance with the designed mounting position, and the mounting position of the laser diode 11 may be shifted by Δα with respect to the marker 91 .

The relationship between the design wavelength λ, the wavelength shift amount Δλ, and the mounting position shift amount Δα is given by the following formula (1). In equation (1), Nc is the core refractive index of the arrayed waveguide diffraction grating, ns is the refractive index of the slab waveguide 14a, d is the distance between the arrayed waveguides 19a (FIG. 2), and ΔL is the arrayed waveguide 19a. and f is the focal length of the slab waveguide 14a.

Furthermore, the alignment of the laser diode 11 and the arrayed waveguide diffraction grating may be performed by oscillating the laser diode 11 using the electrode 92 for the laser diode 11 and attaching an 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 match and the laser light output from the inspection port 93 takes the maximum value. Incidentally, the common port 94 is used for monitoring the deviation of the transmission wavelength of the single arrayed waveguide diffraction grating. According to the optical module mounting method of the first embodiment, the oscillation wavelength can be matched with the transmission wavelength of the arrayed waveguide grating when the laser diode 11 is mounted. It becomes possible to adjust the oscillation wavelength of the laser diode 11 with high precision. Moreover, the mounting method of the first embodiment can relax the requirements for the wavelength accuracy and shape of the arrayed waveguide grating. As a result, the production yield of the arrayed waveguide diffraction grating and thus the optical module is improved.

The mounting process described above is a method for mounting the optical module 10 of the first embodiment described with reference to FIGS. 2 to 4(b). The mounting method of the first embodiment includes steps of measuring the oscillation wavelength of the laser diode 11, measuring the transmission wavelength of the arrayed waveguide diffraction grating, and measuring the transmission wavelength of the laser diode 11 based on the oscillation wavelength and the transmission wavelength. and deriving the mounting position. Such a mounting method includes, for example, a wavelength measurement unit that measures the oscillation wavelength and the transmission wavelength, a computer that calculates the amount of deviation from the design wavelengths of both, and calculates the difference between the design mounting position and the actual mounting position. can be performed automatically and collectively by using a device equipped with

In addition, the mounting method of the first embodiment further includes the step of mounting the laser diode 11 at the mounting position derived in the deriving step. It is conceivable that such processes are automatically performed by combining the above-described computer-equipped device with a robot hand, a manipulator, or the like.

[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 more portions are exposed from the optical waveguide substrate 12. FIG. FIG. 6(a) is a top view showing a region including the slab waveguide 54 of the second embodiment, and FIG. 6(b) is a cross-sectional view taken along arrows Vb and Vb in FIG. 6(a). As shown in FIG. 6(a), the slab waveguide 54 exposes the end surface of the slab waveguide 14a from the optical waveguide substrate 12 in the configuration shown in FIG. 3(a) of the first embodiment. Furthermore, the vicinity of the arrayed waveguide group 19 is also exposed from the optical waveguide substrate 12 . Also in the second embodiment, the slab waveguide 54 is arranged such that the coupling surface 54a to which the laser light _Lp is coupled shown in FIG. 6B is in contact with the end surface 12a. The end surface of the slab waveguide 54 opposite to the coupling surface 54a is defined as an end surface 54b.

In the second embodiment, as in the first embodiment, after the slab waveguide 14a, the arrayed waveguide 19a, the slab waveguide 14b, and the output waveguide 13 are formed on the optical waveguide substrate 12, more than the first embodiment. can be realized by etching the portion of The slab waveguide 14a is processed into a 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 downsizing 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.

[Third embodiment]
Next, a third embodiment of the present disclosure will be described. 7A and 7B are diagrams for explaining the third embodiment, and FIG. 7A is a top view and a diagram showing a region including the slab waveguide 14a of the third embodiment. 7(b) is a cross-sectional view along arrows VIb and VIb in FIG. 7(a). The third embodiment differs from the first embodiment in that the laser diode 11 is arranged farther 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 . Different from the form. The plurality of laser diodes 11 are arranged radially, and the coupling surface 14aa is a curved surface. Each of the plurality of lenses 61 is arranged corresponding to one of the laser diodes 11 . A lens 61 converts the light of the corresponding laser diode 11 into collimated light. The collimated light is condensed in the Y direction by the cylindrical lens 20 and coupled to the coupling surface 14aa.

Here, the effect of arranging the laser diode 11 farther 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 the laser diodes 11 need to be spaced apart due to electrical wiring or the like, the laser diodes 11 cannot be placed within the width of the slab waveguide 14a in the X direction. In order to solve this problem, in the third embodiment, the laser light that spreads beyond the width of the slab waveguide 14a is converted into the collimated light _Lpp by the lens 61 and then coupled to the coupling surface 14aa. In addition, in the third embodiment, by coupling the laser beams to the coupling surface 14aa via the lens 61, the interval between the incident positions 14ap of the plurality of laser beams can be narrowed, so that the focal length f1 of the input waveguide is As a result, the length of the slab waveguide 14a in the Z direction can be shortened. This point is advantageous for miniaturization of the optical module 10 .

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

8A and 8B are diagrams for explaining the fourth embodiment, and FIG. 8A is a top view and a diagram showing a region including the slab waveguide 14c of the fourth embodiment. 8(b) is a cross-sectional view taken along arrows VIIb and VIIb in FIG. 8(a). In the fourth embodiment, the laser diode 11 is arranged farther from the arrayed waveguide diffraction grating than in the third embodiment. In the examples shown in FIGS. 8A and 8B, the laser diode 11 is arranged 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 arranged corresponding to each of the plurality of laser diodes 11, similarly to the third embodiment. However, the lenses 61 of the fourth embodiment are arranged on a straight line along the X-axis in the figure. Further, the optical module of the fourth embodiment includes a cylindrical lens 20 between the lens 61 and the arrayed waveguide diffraction grating that converges laser light in the Y direction. In the fourth embodiment, the traveling direction of the collimated light L _pp is bent by shifting the position of each lens 61 from the center line P _x of the corresponding laser diode 11 in the X direction to the −X direction, thereby coupling the slab waveguide 14 c. All the laser beams are condensed at one point on the surface 14ca. In the fourth embodiment, as shown in FIG. 8B, the distances from the laser diode 11 to the lens 61 and from the lens 61 to the end surface of the optical waveguide substrate 12 are both the focal length f1. According to such a fourth embodiment, even when the laser diode 11 is arranged so that the optical axis is parallel to the Z-axis in the drawing, the laser light can be focused at an appropriate focal length. be possible.

[Fifth embodiment]
Next, a fifth embodiment of the present disclosure will be described. The fifth embodiment differs in that one lens 81 is provided while the fourth embodiment includes a plurality of lenses 61 corresponding to each of the laser diodes 11 . 9A and 9B are diagrams for explaining the fifth embodiment, and FIG. 9A is a top view showing a region including the slab waveguide 14c of the fifth embodiment; 9(b) is a cross-sectional view taken along arrows VIIIb and VIIIb in FIG. 9(a). The lens 81 of the fifth embodiment transmits all laser beams output from the plurality of laser diodes 11 between the laser diodes 11 and the cylindrical lens 20 . The cylindrical lens is arranged so as to be in contact with the end surface of the optical waveguide substrate 12, and converges the laser light in the Y direction in the figure. The spot size in the X direction of the laser light coupled to the coupling surface 14ca is denoted as ω _LD in the drawing.

According to the fifth embodiment, since the plurality of lenses 61 are replaced with one lens, the number of parts of the optical module can be reduced, the assembly accuracy can be relaxed, and the complication of the structure can be eliminated. can.

(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. 10(a) and 10(b) are diagrams for explaining the sixth embodiment, and FIG. 10(a) is a top view and a diagram showing a region including the slab waveguide 54 of the sixth embodiment. 10(b) is a cross-sectional view taken along arrows IXb and IXb in FIG. 10(a). The laser diodes 11 are arranged parallel to each other and the laser light is converted into collimated light _Lpp by the lens 81 . A cylindrical lens 20 is arranged between the lens 81 and the slab waveguide 54 to converge the laser light in the Y direction. The laser light is focused at different positions on the straight coupling surface 54a.

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, by shortening the distance from the laser diode 11 to the lens 81, the distance from the laser diode 11 to the arrayed waveguide grating is made the focal length f1. In such a sixth embodiment, the laser light is spread and made incident on the end surface behind the coupling surface 54a of the slab waveguide 54, so that the laser light is spread and condensed and made incident on the slab waveguide 14c. The focal length is shorter than in the fourth and fifth embodiments, which is advantageous for downsizing the optical module.

10, 100 optical module 11 laser diode 12 optical waveguide substrate 12a end surface 13

output waveguides

14a, 14b, 14c, 54 slab waveguides 14aa, 14ca, 54a coupling surface 14ap incidence positions 15, 17, 61, 81 lens 16 isolator 18 fiber 19 Arrayed waveguide 19a Arrayed waveguide 20 Cylindrical lens 21 Si substrate 22 Subassembly 23 Resin member 25 Ceramic package 26 Supporting portion 28 Laser chip 91 Marker 92 Electrode 93 Inspection port 95 Removal region

Claims

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 diffraction grating includes a first slab waveguide having a coupling surface to which light from the optical element is coupled, a plurality of arrayed waveguides connected to the first slab waveguide, and a plurality of the arrayed waveguides. a second slab waveguide connected to a wave path, wherein at least part of the coupling surface of the first slab waveguide is in contact with an end surface of the optical waveguide substrate facing the optical element, or , the optical module, wherein the coupling surface is in a space outside the optical waveguide substrate and arranged to intersect with the end surface.
The optical module according to claim 1, wherein the optical element is spaced apart from the coupling surface, and light from the optical element is coupled to the coupling surface through the space.
a spot size adjustment unit located between the arrayed waveguide grating and the optical element for adjusting the spot size of the end surface of the arrayed waveguide grating or the optical element;
3. The optical module according to claim 1, wherein said spot size adjuster includes at least one of a cylindrical lens and a spot size converter for condensing light in a direction perpendicular to the main surface of said optical waveguide substrate.
The optical module according to any one of claims 1 to 3, comprising a lens interposed between the arrayed waveguide diffraction grating and the optical element for converting light emitted by the optical element into collimated light.
An optical waveguide substrate having an arrayed waveguide grating, and an optical element for coupling an optical signal to the arrayed waveguide diffraction grating, the arrayed waveguide diffraction grating forming a coupling surface to which the light of the optical element is coupled. a first slab waveguide, a plurality of arrayed waveguides connected to the first slab waveguide, and a second slab waveguide connected to the arrayed waveguide, wherein the first slab waveguide has , 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 located in a space outside the optical waveguide substrate and is arranged to intersect with the end surface. An optical module mounting method for mounting an optical module with
a step of measuring the 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. The optical module mounting method according to claim 5, further comprising the step of mounting said optical element at the mounting position derived in said mounting position deriving step.
The method of 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.