Optical waveguide device, optical modulator, and optical transmission apparatus

Abstract

In an optical waveguide device provided with a lens for coupling an optical waveguide provided on an optical waveguide substrate and an optical fiber, an increase in optical coupling loss between the optical waveguide and the optical fiber due to a fixing structure of the optical waveguide substrate and the lens is suppressed. In an optical waveguide device (3) provided with an optical waveguide substrate (20) provided with an optical waveguide (30) and a plurality of lenses (42, 44, 52) optically coupling the optical waveguide (30) and optical fibers (10, 11), the optical waveguide (30) includes at least one input waveguide (36) into which input light enters and at least two output waveguides (38) from which output light forming output light exits. An end portion (32) of the input waveguide (36) and end portions (34, 35) of the output waveguides (38) are formed on the same end surface (22) of the optical waveguide substrate (20), at least three lenses (42, 44, 52) are disposed on the end surface (22) so as to correspond to each of the at least one input waveguide (36) and the at least two output waveguides (38), and the at least three lenses (42, 44, 52) are configured from a lens array (40) in which at least two lenses (42, 44) are integrally formed and a single lens (50).

Description

Technical Field

[0001] The present invention relates to an optical waveguide device, an optical modulator and an optical transmitting device. Background Art

[0002] In high-speed / large-capacity optical fiber communication systems, optical transmission devices equipped with waveguide optical elements (hereinafter referred to as optical modulators) for optical modulation are often used. Among them, optical modulators using LiNbO3 (hereinafter referred to as LN) with electro-optical effect as substrates can achieve optical modulation characteristics with less light loss and wideband compared to modulators using semiconductor materials such as indium phosphide (InP), silicon (Si) or gallium arsenide (GaAs), and are therefore widely used in high-speed / large-capacity optical fiber communication systems.

[0003] The modulation method in the optical fiber communication system has been influenced by the trend of increasing transmission capacity in recent years, and multi-value modulation such as QPSK (Quadrature Phase Shift Keying) and DP-QPSK (Dual Polarization - Quadrature Phase Shift Keying), or transmission standards that incorporate polarization wave multiplexing into multi-value modulation have become mainstream.

[0004] The popularity of Internet services in recent years has led to a further increase in the amount of communication information, and research on the continued high-speed and high-capacity optical communication systems is also progressing. On the other hand, the demand for miniaturization of devices remains unchanged. In addition to the miniaturization of optical modulators themselves, efforts are also being made to accommodate electronic circuits and optical modulators in one housing and integrate them into optical modulators.

[0005] For example, a light modulation device has been proposed in which a light modulation element and a high-frequency drive amplifier for driving the light modulation element are integrated and housed in a housing, and light input and output parts are arranged in parallel on one surface of the housing, thereby achieving miniaturization and integration.

[0006] As such an optical modulation device, there is conventionally known an optical modulation device in which a microlens array including a plurality of lenses integrally formed is provided on a light incident and output surface of a substrate provided with an optical waveguide constituting an optical modulation element (see Patent Document 1).

[0007] In the optical modulation device, input light incident from an input optical fiber is focused by a lens of a microlens array and incident on an input waveguide provided on the substrate. Furthermore, two output lights respectively emitted from two output waveguides provided on the substrate are collimated by two lenses of the microlens array.

[0008] In addition, in an optical modulator device in which a microlens array integrally equipped with a plurality of lenses is provided on the light incident and output surfaces of a substrate provided with an optical waveguide constituting an optical modulator, there is the following situation: by selecting the respective focal lengths of the microlens array and a coupling lens provided on the optical fiber, the beam diameters of the input light and the output light are transformed, and the optical fiber is coupled to the optical modulator via the lens array.

[0009] In this light modulation device, the microlens array is attached to the light modulation element via an adhesive.

[0010] However, in this light modulation device, when the microlens array is mounted on a substrate, the thickness of the adhesive in the focal direction of the microlens array may be non-uniform over the entire light incident and emission surface.

[0011] Therefore, in the optical modulation device, the microlens array may be mounted in a tilted state with respect to the light incident and exiting surfaces, which may increase the optical coupling loss between the optical modulation element and the optical fiber.

[0012] Prior Art Literature

[0013] Patent Literature

[0014] Patent Document 1: Japanese Patent Application Publication No. 2021-149036 Summary of the invention

[0015] Summary of the Invention

[0016] Problems to be solved by the invention

[0017] In view of the above background, in an optical waveguide device including a lens for coupling an optical waveguide provided on a substrate and an optical fiber, it is required to suppress an increase in optical coupling loss between the optical waveguide and the optical fiber caused by a fixing structure of the substrate and the lens.

[0018] Solutions to Solve Problems

[0019] One embodiment of the present invention relates to an optical waveguide device, comprising: an optical waveguide substrate provided with an optical waveguide; and a plurality of lenses for optically coupling the optical waveguide with an optical fiber, wherein the optical waveguide includes at least one input waveguide for inputting input light and at least two output waveguides for emitting output light forming output light, and ends of the input waveguide and ends of the output waveguide are formed on the same end face of the optical waveguide substrate, and at least three lenses are arranged on the end face corresponding to the at least one input waveguide and the at least two output waveguides, respectively, and the at least three lenses are composed of a lens array in which at least two lenses are integrally formed and a single lens.

[0020] According to another aspect of the present invention, in the lens array, the lens corresponding to the input waveguide and the lens corresponding to one of the output waveguides are formed integrally.

[0021] According to another aspect of the present invention, in the lens array, the lenses corresponding to the at least two output waveguides are formed integrally.

[0022] According to another aspect of the present invention, the optical waveguide substrate is provided with two output waveguides, and in the lens array, two lenses corresponding to the two output waveguides are formed integrally.

[0023] According to another aspect of the present invention, an angle of the input light relative to the optical axis of the input waveguide is smaller than an angle of the output light relative to the optical axis of the output waveguide.

[0024] According to another aspect of the present invention, the lenses corresponding to the two output waveguides respectively have a mounting surface, which is a surface mounted on the end surface opposite to the end surface, and the mounting surface is mounted on the end surface in such a way that reflected light of the output light from each of the output waveguides at the mounting surface is directed in a direction deviating from a direction in which the other output waveguides are present.

[0025] According to another aspect of the present invention, the optical waveguide substrate is joined to a supporting substrate, the lens has a mounting surface, which is a surface mounted on the end face opposite to the end face, and the mounting surface is mounted on the end face in such a way that reflected light of the output light from each of the output waveguides at the mounting surface is directed in a direction deviating from the supporting substrate.

[0026] Another aspect of the present invention relates to an optical modulator comprising: any one of the above-mentioned optical waveguide devices; a housing that accommodates the optical waveguide device; and an optical fiber that inputs or outputs a light wave to or from the optical waveguide from the outside of the housing.

[0027] Another aspect of the present invention relates to an optical transmission device including: the optical modulator described above; and an electronic circuit that outputs a modulation signal that causes the optical modulator to perform a modulation operation.

[0028] Effects of the Invention

[0029] According to the present invention, in an optical waveguide device including a lens for coupling an optical waveguide provided on a substrate and an optical fiber, an increase in optical coupling loss between the optical waveguide and the optical fiber caused by a fixing structure of the substrate and the lens can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a diagram showing the structure of the optical modulator according to the first embodiment of the present invention.

[0031] Figure 2 The diagram shows an optical waveguide device, an optical axis of an optical waveguide at an input end of an optical modulation element, and a light beam direction of a lens.

[0032] Figure 3 It is a diagram showing the structure of an optical waveguide device according to a modification of the first embodiment.

[0033] Figure 4 It is a diagram showing the structure of an optical waveguide device according to a modification of the first embodiment.

[0034] Figure 5 It is a diagram showing the structure of an optical modulator according to a second embodiment of the present invention.

[0035] Figure 6 It is a diagram showing the structure of the optical transmission device of the present invention. DETAILED DESCRIPTION

[0036] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0037] <First Embodiment>

[0038] First, the first embodiment will be described.

[0039] Figure 1 FIG. 1 is a diagram showing the structure of an optical modulator 1 using an optical modulator 4 which is an optical waveguide element according to the first embodiment of the present invention. Figure 1 In FIG. 4 , the wavelength plate for rotating the polarization direction of the output light from the lens 44 is omitted. Figure 1 to Figure 6 In the figure, for convenience of explanation, the adhesive 70 is indicated by dots.

[0040] like Figure 1 As shown, the optical modulator 1 includes a housing 2. An optical waveguide device 3 and a drive circuit element 6 are housed inside the housing 2.

[0041] An input optical fiber 10 and an output optical fiber 11 are provided on one side of the housing 2. The input optical fiber 10 is an optical fiber for introducing input light into the optical modulator 4. The output optical fiber 11 is an optical fiber for guiding modulated light (modulated light, output light) emitted from the optical modulator 4 to the outside of the housing 2. The input optical fiber 10 and the output optical fiber 11 are fixed to the housing 2 by holding members 12 and 13, respectively. The holding members 12 and 13 hold coupling lenses 14 and 15, respectively. The mode field diameters of the input optical fiber 10 and the output optical fiber 11 are, for example, 10 μm.

[0042] In the housing 2, an optical window 9 made of a light-transmitting material such as glass is provided at a position corresponding to the input optical fiber 10 and the output optical fiber 11 on the side surface where the input optical fiber 10 and the output optical fiber 11 are provided. By providing the optical window 9, the housing 2 becomes an airtight closed structure capable of ensuring airtightness.

[0043] The drive circuit element 6 is disposed adjacent to the light modulator element 4 included in the optical waveguide device 3, and includes a drive circuit that outputs a modulation signal for modulating the light modulator element 4. The drive circuit element 6 is connected to the light modulator element 4 via predetermined wiring such as wire bonding.

[0044] The optical waveguide device 3 includes a light modulation element 4 , a microlens array 40 , and a single-eye lens 50 .

[0045] The optical modulation element 4 is, for example, an optical functional element that performs optical modulation. The optical modulation element 4 has, for example, a DP-QPSK modulator structure. The optical modulation element 4 includes an optical waveguide substrate 20 provided with an optical waveguide 30. The optical waveguide substrate 20 is formed of LN, a semiconductor, or the like.

[0046] A ridge-type optical waveguide 30 is formed on the optical waveguide substrate 20. In the present embodiment, the dimension along the thickness direction of the optical waveguide substrate 20, that is, the height dimension of the optical waveguide 30 is set to, for example, 2 μm or less.

[0047] The optical waveguide 30 includes an input waveguide 36 for inputting input light and two output waveguides 38 for outputting output light. The optical waveguide 30 bends the propagation direction of light on the optical waveguide substrate 20 by 180 degrees.

[0048] Thus, the input end 32 which is the end of the input waveguide 36 and the first output end 34 and the second output end 35 which are the output ends of the two output waveguides 38 are arranged on one end surface 22 of the optical waveguide substrate 20 .

[0049] The input light enters the input end 32, and two outgoing lights forming the output light are emitted from the first output end 34 and the second output end 35. The end face 22 functions as a light incident and output face.

[0050] In the optical waveguide substrate 20 , the input waveguide 36 and the output waveguide 38 each extend from the end face 22 toward the end face 24 opposite to the end face 22 .

[0051] In the optical waveguide 30, a spot size converter 39 is provided at each of the input end 32 and the first output end 34 and the second output end 35. The spot size converter 39 changes the mode field diameter of the light wave propagating in the optical waveguide 30. The mode field diameter of the spot size converter 39 is formed to be 4 micrometers or less at the end portions located on the respective sides of the input end 32, the first output end 34 and the second output end 35.

[0052] It should be noted that in the present embodiment, the spot size converter 39 is formed on the optical waveguide substrate 20 , but the present invention is not limited to this, and a configuration in which the spot size converter 39 is not formed may be adopted.

[0053] In order to improve the mechanical strength of the light modulation element 4, a reinforcing substrate 26 ( Figure 4 The reinforcing substrate 26 is formed of a SiO2 substrate or the like, and has a thickness of, for example, about 1 mm. The reinforcing substrate 26 corresponds to the "supporting substrate" of the present disclosure.

[0054] A reinforcing member 28 ( Figure 4 The reinforcing member 28 is provided on a surface of the optical waveguide substrate 20 opposite to the surface to which the reinforcing substrate 26 is bonded. The reinforcing member 28 is formed of a semiconductor substrate such as LN, SiO2, Si, etc., and has a thickness dimension similar to that of the reinforcing substrate 26, for example.

[0055] In the optical waveguide substrate 20, a micro lens array 40 is arranged on one end face 22. Furthermore, coupling lenses 14 and 15 are arranged on the input optical fiber 10 and the output optical fiber 11, respectively. The micro lens array 40 is formed by integrating a plurality of lenses. The micro lens array 40 is an optical component that optically couples the optical waveguide 30 of the optical modulator 4 with the input optical fiber 10 and the output optical fiber 11 together with the coupling lenses 14 and 15. In the present embodiment, the micro lens array 40 is formed of a glass material and has two lenses 42 and 44. The two lenses 42 and 44 are arranged in the micro lens array 40 with a predetermined distance (pitch) between them.

[0056] The lenses 42 and 44 have substantially the same focal length. By selecting the focal lengths of the lenses 42 and 44 and the coupling lenses 14 and 15 , the mode field diameter of the spot size converter 39 can be converted into the mode field diameters of the input optical fiber 10 and the output optical fiber 11 .

[0057] The microlens array 40 includes a mounting surface 46 which is a flat surface extending in a direction intersecting the focal directions of the lenses 42 and 44. The microlens array 40 is mounted on the optical waveguide substrate 20 by bonding the mounting surface 46 to one end surface 22 via an adhesive 70 so as to face the mounting surface 46.

[0058] The adhesive 70 is, for example, a so-called photocurable resin that is cured by ultraviolet light or the like.

[0059] As described above, the reinforcing member 28 is disposed on one end surface 22 of the optical waveguide substrate 20, so that the microlens array 40 can be easily mounted on the end surface 22. Furthermore, by providing the reinforcing member 28, the bonding strength between the end surface 22 and the microlens array 40 in the optical waveguide substrate 20 is improved.

[0060] The lens 42 of the microlens array 40 mounted on the optical waveguide substrate 20 optically couples the input end 32 with the input optical fiber 10 together with the coupling lens 14 , and the lens 44 optically couples the first output end 34 with the output optical fiber 11 together with the coupling lens 15 .

[0061] Figure 2 1 is a diagram showing the optical axis L1 of the optical waveguide device 3 and the optical waveguide 30 at the end surface 22 of the optical waveguide substrate 20, and the light directions F1, F2, and F3 at the lenses 42, 44, and 52. Figure 2 In FIG. 1 , for convenience of explanation, the optical axis L1 is indicated by a two-dot chain line, and is indicated at positions passing through lenses 42, 44, and 52, respectively. Figure 2 In FIG. 1 , the light directions F1 , F2 , and F3 of the lenses 42 , 44 , and 52 are indicated by single-dot chain lines.

[0062] It should be noted that Figure 2 The light direction F1 shown indicates the optical axis direction of the input light incident on the lens 42 , and the light directions F2 and F3 indicate the optical axis directions of the outgoing light emitted from the lenses 44 and 52 , respectively.

[0063] When the microlens array 40 is mounted on the optical waveguide substrate 20, the mounting surface 46 is bonded to one end surface 22 in such a manner that the light direction F1 of the lens 42 extends in the same direction as the optical axis L1 of the optical waveguide 30. Figure 2 As shown, the microlens array 40 is mounted on the optical waveguide substrate 20 so that an angle θ1 formed between the optical axis L1 and the light direction F1 of the lens 42 is smaller than an angle θ2 formed between the optical axis L1 and the light direction F2 of the lens 44 .

[0064] As a result, in the optical waveguide device 3 , the coupling loss of the input light via the lens 42 of the microlens array 40 can be reduced, and thus the extinction ratio characteristic of the optical waveguide device 3 can be improved.

[0065] As described above, when the microlens array 40 is mounted on the optical waveguide substrate 20, the lens 44 is mounted so that the light direction F2 forms an angle θ2 with respect to the optical axis L1. The angle θ2 is determined based on the angle θ1, the tolerance of the spacing between the lens 42 and the lens 44, and the distance between the input end 32 and the first output end 34 in the longitudinal direction of the end face 22.

[0066] like Figure 1 As shown, in the optical waveguide substrate 20, a single-eye lens 50 is provided on one end surface 22. The single-eye lens 50 is an optical member including a lens 52 as a single lens, and optically couples the output waveguide 38 of the optical modulation element 4 and the output optical fiber 11 together with the coupling lens 15. The single-eye lens 50 is formed of a glass material.

[0067] The lens 52 has substantially the same focal length as the lenses 42 and 44 . By selecting the focal length of the coupling lens 15 , the beam diameter of the output optical fiber 11 can be made consistent with the beam diameter from the spot size converter 39 .

[0068] The single-eye lens 50 includes a mounting surface 56 as a flat surface on the opposite side of the convex surface of the lens 52. The single-eye lens 50 is mounted on the optical waveguide substrate 20 by bonding the mounting surface 56 to one end surface 22 via an adhesive 70 so as to face each other.

[0069] As described above, since the reinforcing member 28 is provided on the end surface 22 of the optical waveguide substrate 20 , the single-eye lens 50 can be easily attached to the end surface 22 .

[0070] The lens 52 of the monocular lens 50 , together with the coupling lens 15 , couples the second output end 35 to the output optical fiber 11 .

[0071] Inside the housing 2, a polarization combining unit 8 is arranged between the optical waveguide device 3 and the output optical fiber 11 to combine the polarization waves of the output lights emitted from the lens 44 and the lens 52. The output light combined by the polarization combining unit 8 is coupled to the output optical fiber 11 via the coupling lens 15 and becomes the output light of the optical modulator 1.

[0072] As described above, when the microlens array 40 is mounted on the optical waveguide substrate 20 , the lens 44 is mounted so that the light direction F2 forms an angle θ2 with respect to the optical axis L1 .

[0073] Here, when the lens 52 is integrally provided in the micro lens array 40, the angle θ3 formed by the optical axis L1 and the light direction F3 of the lens 52 is determined according to the tolerance of the spacing between the lens 42, the lens 44 and the lens 52 in the micro lens array 40. For example, when the focal lengths of the lenses 44 and 52 are 0.5 mm or less, an angle difference of about 1 degree or less is generated between the angles θ2 and θ3 of the output light from each lens, and when the two output lights are coupled to the output optical fiber 11, an increase in optical coupling loss of 1 dB or more is estimated.

[0074] like Figure 2 As shown, in the optical waveguide device 3 of the present embodiment, the lens 52 is divided from the lenses 42 and 44 and provided in the single-eye lens 50 which is an optical member different from the microlens array 40 .

[0075] Thus, in the optical waveguide device 3, the lens 52 can be mounted on the optical waveguide substrate 20 so as to be at a predetermined angle θ3 regardless of the angle θ2. Therefore, in the optical waveguide device 3, compared with the case where the lenses 42, 44, and 52 are provided as an integrated microlens array, the loss of the two output lights when coupled to the output optical fiber 11 can be suppressed.

[0076] As described above, the outgoing light emitted from the lens 44 and the lens 52 is combined by the polarization combining unit 8 and input to the output optical fiber 11. In this case, when the position of the so-called beam waist, which is the part where the diameter of the beam becomes the thinnest in the outgoing direction, is near the center of the coupling distance, the outgoing light emitted from the lens 44 and the outgoing light emitted from the lens 52 are in the best coupling state, and the coupling loss can be reduced. The position of the beam waist is determined by the distance between the first output end 34 and the lens 44 and the distance between the second output end 35 and the lens 52, in other words, by the distance between the first output end 34 and the mounting surface 46 and the distance between the second output end 35 and the mounting surface 56.

[0077] In the optical waveguide device 3 of the present embodiment, the lens 52 is provided in the single-eye lens 50 which is independent of the microlens array 40 in which the lens 44 is provided.

[0078] In the optical waveguide device 3, the lens 52 is separated from the lenses 42 and 44. Thus, in the optical waveguide device 3, for example, the mounting position and / or angle of the lens 44 can be adjusted so that the beam waist of the outgoing light emitted from the lens 44 is near the center of the coupling distance to the output optical fiber 11. In addition, in the optical waveguide device 3, the mounting position and / or angle of the lens 52 can be adjusted so that the beam waist of the outgoing light emitted from the lens 52 separately from the lens 44 is near the center of the coupling distance to the output optical fiber 11.

[0079] Therefore, in the optical waveguide device 3 , compared with a case where the lenses 42 , 44 , and 52 are provided as an integrated microlens array, the coupling loss between the lens 44 or the lens 52 and the output optical fiber 11 can be suppressed.

[0080] In the present embodiment, scattered light generated in the optical waveguide substrate 20 may enter the microlens array 40 and the single-eye lens 50 .

[0081] When the lenses 42, 44, and 52 are formed as an integrated microlens array, scattered light entering each lens may enter the other lens and deteriorate the extinction ratio of the optical waveguide device 3. In contrast, in this embodiment, the lenses 42, 44 and the lens 52 are formed independently, and an air gap is formed between the microlens array 40 and the single-eye lens 50.

[0082] Thus, in the optical waveguide device 3, even if scattered light generated by the optical waveguide substrate 20 enters the microlens array 40, it is possible to suppress the scattered light from entering the single-eye lens 50. Similarly, in the optical waveguide device 3, even if scattered light generated by the optical waveguide substrate 20 enters the single-eye lens 50, it is possible to suppress the scattered light from entering the microlens array 40. Therefore, in the optical waveguide device 3, the extinction ratio can be improved, and the so-called crosstalk can be improved.

[0083] Next, a modification of the present embodiment will be described.

[0084] Figure 3 FIG. 2 is a diagram showing the structure of an optical waveguide device 3 according to a first variation of the present embodiment. Figure 3 In FIG. 1 , the spot size converter 39 is omitted for convenience of explanation, and the reflected light L2 is indicated by an arrow.

[0085] In the optical waveguide device 3 of this modified example, the microlens array 40 is fixed to the optical waveguide substrate 20 at an angle to prevent the reflected light L2 generated by the lens 42 and the lens 44 from being directed toward the optical waveguide 30 coupled to the lens 52. Similarly, in the optical waveguide device 3, the single-eye lens 50 is fixed to the optical waveguide substrate 20 at an angle to prevent the reflected light L2 generated by the lens 52 from being directed toward the optical waveguide 30 coupled to the lenses 42 and 44.

[0086] Thus, in the optical waveguide device 3, crosstalk between the optical waveguides 30 can be suppressed. In particular, in this modification, crosstalk between the two output optical waveguides 30 coupled to the lenses 44 and 52 can be suppressed, so that more excellent optical waveguide device characteristics can be obtained.

[0087] In the present modification, the optical waveguide device 3 is formed so that the angle formed by the end face 22 and the mounting surface 56 and the angle formed by the end face 22 and the mounting surface 46 are both 10 degrees or less.

[0088] It should be noted that the angle formed by the end surface 22 and the mounting surface 56 and the angle formed by the end surface 22 and the mounting surface 46 may be less than 5 degrees, less than 3 degrees, or less than 1 degree.

[0089] Figure 4 It is a diagram showing the structure of an optical waveguide device 3 according to Modification 2 of the present embodiment.

[0090] like Figure 4 As shown, in this modification, the microlens array 40 and the single-eye lens 50 are mounted on the optical waveguide substrate 20 so as to reflect the light L2 toward the reinforcing member 28 .

[0091] Here, in the optical waveguide device 3, the single-eye lens 50 may be mounted on the optical waveguide substrate 20 so that the reflected light L2 is directed toward the reinforcing substrate 26. However, in such an optical waveguide device 3, the reflected light L2 propagates inside the reinforcing substrate 26, which may deteriorate the crosstalk characteristics.

[0092] The optical waveguide device 3 of this modification example is as follows Figure 4 By mounting the single-eye lens 50 on the optical waveguide substrate 20 in this manner, the reflected light L2 at the mounting surface 56 is directed away from the reinforcing substrate 26. Thus, in the optical waveguide device 3, degradation of crosstalk characteristics can be suppressed, and more excellent optical waveguide device characteristics can be obtained.

[0093] As described above, in the optical waveguide device 3 , the microlens array 40 is mounted on the optical waveguide substrate 20 so that reflected light at the mounting surface 46 is directed in a direction deviating from the reinforcing substrate 26 .

[0094] In addition, it can be achieved by simultaneously satisfying Figure 3 The slope and Figure 4 At least one of the microlens array 40 and the single-eye lens 50 is mounted on the optical waveguide substrate 20 in the manner of the slope as shown. As a result, in the optical waveguide device 3, the crosstalk characteristics are further improved.

[0095] <Second Embodiment>

[0096] Next, a second embodiment of the present invention will be described.

[0097] Figure 5 FIG. 2 is a diagram showing the structure of an optical waveguide device 100 according to a second embodiment of the present invention. Figure 5 In Figure 1 The same parts are denoted by the same reference numerals, and description thereof is omitted.

[0098] and Figure 1 The optical waveguide device 3 shown in FIG. Figure 5 The optical waveguide device 100 shown is provided in an optical modulator 1 and is housed in a housing 2 in which an input optical fiber 10 and an output optical fiber 11 are provided.

[0099] like Figure 5 As shown, in the optical waveguide device 100 of the present embodiment, the single-eye lens 50 includes the lens 42 , and the microlens array 40 includes the lens 44 and the lens 52 in an integrated manner.

[0100] In the optical waveguide device 100, the lens 44 of the microlens array 40 and the coupling lens 15 optically couple the first output end 34 to the output optical fiber 11. Similarly, the lens 52 of the microlens array 40 and the coupling lens 15 optically couple the second output end 35 to the output optical fiber 11.

[0101] The lens 42 of the monocular lens 50 , together with the coupling lens 14 , optically couples the input end 32 to the input optical fiber 10 .

[0102] Thus, in the optical waveguide device 100, the angle θ2 formed between the optical axis L1 and the light direction F2 of the lens 44 and the angle θ3 formed between the optical axis L1 and the light direction F3 of the lens 52 can be determined independently of the angle θ1 formed between the optical axis L1 and the light direction F1 of the lens 42. Therefore, in the optical waveguide device 100, the optical coupling loss of the lens 42 can be reduced.

[0103] In the lenses 44 and 52, each outgoing light is coupled to one output optical fiber 11, so it is necessary to adjust the angle and position of the lenses 44 and 52. In the optical waveguide device 100 of the present embodiment, the lenses 44 and 52 are independent of the lens 42, so it is possible to simplify the alignment of the lenses 44 and 52. Therefore, in the optical waveguide device 100, the incident intensity of the outgoing light emitted from each lens 44 and 52 to the output optical fiber 11 can be adjusted.

[0104] Here, as in the above-mentioned first and second embodiments, the configuration in which the spot size converter 39 is provided in the ridge-type optical waveguide 30 requires adjustment of the lens with higher precision.

[0105] Therefore, the optical waveguide device 3 or 100 having a degree of freedom in the amplitude of optical coupling adjustment is preferably an optical waveguide structure having a mode field diameter of 5 μm or less, 3 μm or less, or further 2 μm or less.

[0106] Figure 6 It is a diagram showing the structure of the optical transmission device 200 of the present invention.

[0107] like Figure 1 , Figure 5 As shown, in the above-mentioned embodiments 1 and 2, the above-mentioned optical waveguide device 3 and 100 are accommodated in the interior of the housing 2, and an optical fiber for inputting and outputting light waves to the outside of the housing 2 is provided in the optical waveguide 30 of the optical modulator 4, thereby forming the optical modulator 1.

[0108] like Figure 6As shown, in the above-mentioned embodiments 1 and 2, the optical modulator 1 includes a digital signal processor for generating an electrical signal input to the optical waveguide substrate 20, an electronic circuit 210 composed of a driver IC, a laser light source, a control circuit, etc., thereby constituting an optical transmitter 200. The electronic circuit 210 may be arranged inside the same housing 2 as the optical waveguide element, or may be arranged as shown in FIG. Figure 6 The configuration is shown on the outside of the housing 2.

[0109] However, the above-mentioned embodiment is one aspect of the present invention, and it is of course possible to appropriately change it within the scope not departing from the gist of the present invention. In addition, other embodiments can be configured by combining the respective structures described in the above-mentioned embodiments 1 and 2.

[0110] For example, in the above-mentioned first and second embodiments, a light source such as a light emitting element such as a laser diode may be mounted on the input end 32 instead of the input optical fiber 10 .

[0111] In the above-mentioned first and second embodiments, for example, one input end 32 and two output ends are provided on the optical waveguide substrate 20 . However, the present invention is not limited thereto, and a plurality of input ends and one or more than three output ends may be provided on the optical waveguide substrate 20 .

[0112] Unless otherwise specified, the horizontal and vertical directions, various numerical values, and shapes in the above-mentioned embodiments include a range in which the same functions and effects as those of these directions, numerical values, and shapes are exerted, that is, a so-called equivalent range.

[0113] Description of Reference Numerals

[0114] 1…optical modulator, 2…housing, 3, 100…optical waveguide device, 4…optical modulation element, 9…optical window, 10…input optical fiber (optical fiber), 11…output optical fiber (optical fiber), 14, 15…coupling lens, 42, 44, 52…lens, 20…optical waveguide substrate, 22, 24…end face, 30…optical waveguide, 32…input end (end), 34…first output end (end), 35…second output end, (end) 36…input waveguide, 38…output waveguide, 39…spot size converter, 40…micro lens array, 46, 56…mounting surface, 50…monocular lens, 70…adhesive.

Claims

1. An optical waveguide device comprising: an optical waveguide substrate provided with an optical waveguide; and A plurality of lenses are used to optically couple the optical waveguide with the optical fiber, wherein: The optical waveguide includes at least one input waveguide for input light to be incident and at least two output waveguides for outputting output light to form output light. The end of the input waveguide and the end of the output waveguide are formed on the same end surface of the optical waveguide substrate, At least three lenses are arranged on the end surface corresponding to the at least one input waveguide and the at least two output waveguides, respectively. The at least three lenses are composed of a lens array in which at least two lenses are integrally formed and a single lens.

2. The optical waveguide device according to claim 1, wherein In the lens array, the lens corresponding to the input waveguide and the lens corresponding to one of the output waveguides are formed integrally.

3. The optical waveguide device according to claim 1, wherein In the lens array, the lenses corresponding to the at least two output waveguides are formed integrally.

4. The optical waveguide device according to claim 1 or 3, wherein: The optical waveguide substrate is provided with two output waveguides. In the lens array, two lenses corresponding to the two output waveguides are formed integrally.

5. The optical waveguide device according to any one of claims 1 to 4, wherein: The angle of the input light relative to the optical axis of the input waveguide is smaller than the angle of the output light relative to the optical axis of the output waveguide.

6. The optical waveguide device according to any one of claims 1 to 5, wherein: The lenses corresponding to the two output waveguides respectively include mounting surfaces, which are surfaces mounted on the end surface facing the end surface. The mounting surface is mounted on the end surface so that reflected light of output light from each of the output waveguides at the mounting surface is directed in a direction deviated from a direction in which other output waveguides are present.

7. The optical waveguide device according to any one of claims 1 to 6, wherein: The optical waveguide substrate is bonded to a supporting substrate. The lens includes a mounting surface, the mounting surface being a surface mounted on the end surface opposite to the end surface, The mounting surface is mounted on the end surface so that reflected light of output light from each of the output waveguides at the mounting surface is directed in a direction deviating from the support substrate.

8. An optical modulator comprising: The optical waveguide device according to any one of claims 1 to 7; a housing for accommodating the optical waveguide device; and The optical fiber inputs or outputs a light wave from the outside of the housing relative to the optical waveguide.

9. An optical transmission device, comprising: The light modulator of claim 8; and The electronic circuit outputs a modulation signal for causing the optical modulator to perform a modulation operation.

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