Optical waveguide element, optical modulator using same, and optical transmission device

Abstract

The purpose of the present invention is to provide an optical waveguide element in which the effective area of a chip of an optical waveguide substrate is ensured, the increase in the three-dimensional volume of the optical waveguide element is suppressed, and the manufacturing process for electrical wiring is simplified. Also provided is an optical modulator in which the wiring structure of a substrate on which an optical waveguide is formed is simplified. This optical waveguide element is provided with: an optical waveguide substrate (1) on which an optical waveguide (10) is formed; and an auxiliary substrate (SS) disposed on the optical waveguide substrate (1) and bonded to the optical waveguide substrate (1), the optical waveguide element being characterized in that electrical wirings (EP11, EP21, EPG1, EL1, EL2, ELG, EP12, EP22, and EPG2) are provided on a surface of the auxiliary substrate (SS) on the opposite side of the surface bonded to the optical waveguide substrate (1).

Description

Technical Field

[0001] The present invention relates to an optical waveguide element and an optical modulator and an optical transmitting device using the same, and particularly to an optical waveguide element comprising an optical waveguide substrate having an optical waveguide formed thereon, an auxiliary substrate disposed on the optical waveguide substrate and bonded to the optical waveguide substrate, and an optical modulator and an optical transmitting device using the same. Background Technology

[0002] As optical communication systems become faster and more powerful, the performance and density of optical modulators used in these systems are also increasing. For example, with the miniaturization of optical waveguide components (chips), the wiring connecting the internal and external electrical connections of the chip becomes more complex, as seen in the High Bandwidth-Coherent Driver Modulator (HB-CDM).

[0003] Figure 1 This is a plan view illustrating a portion of the wiring connected to the optical waveguide elements. On the optical waveguide substrate 1, where the optical waveguide 10 is formed, light-receiving elements (PD1, PD2) for monitoring light waves propagating in the optical waveguide are arranged. The optical waveguide elements are housed within a housing CA, and connecting pins (PS1, PS2, PG) that transmit electrical signals from within the housing are directly connected to the light-receiving elements via wires (W1, W2, WG) (wire bonding).

[0004] On the other hand, the input portion and the output portion of the light wave to the optical waveguide element are arranged on one side of the optical waveguide substrate to realize the long side direction of the optical waveguide element ( Figure 1 The lateral shortening will also simplify the input / output of light waves to the optical waveguide element. For example... Figure 1 As shown, by folding the optical waveguide 10, the width of the chip ( Figure 1 The longitudinal dimension of the conductor becomes larger. As a result, the conductor (W1, etc.) becomes longer and tilts, making contact with other conductors or wiring formed on the optical waveguide substrate 1, which can cause a short circuit.

[0005] In contrast, such as Figure 2 As shown, relay wiring (EL1, EL2, ELG) is provided on the optical waveguide substrate 1, and the conductors (W11, W21, WG1 and W12, W22, WG2) are also made short. This type of relay wiring occupies a portion of the optical waveguide substrate, thus limiting the space (effective area of ​​the chip) required for the optical waveguide 10 or the control electrodes used to control the light waves on the substrate 1, which is also a reason for the large size of the chip.

[0006] Figure 3This is a diagram showing the relay substrate RS, as shown in Patent Document 1, positioned above the optical waveguide substrate 1, away from the substrate 1. Figure 3 In this configuration, the signal from the light-receiving element PD disposed on the optical waveguide substrate 1 is exported to the outside of the substrate 1 via wiring EL on the relay substrate. Thus, by arranging the relay substrate three-dimensionally, stable electrical wiring can be achieved without reducing the effective area of ​​the chip. However, the optical waveguide substrate 1 and the relay substrate need to be fixed at certain intervals to implement the electrical wiring, which complicates the manufacturing process. Furthermore, [the text abruptly ends here, likely due to an incomplete sentence or missing information]. Figure 3 The thickness of the optical waveguide substrate 1 in the vertical direction of the attached diagram is also increased, and the thickness of the frame (package) containing the optical waveguide substrate 1 is also increased, which hinders miniaturization.

[0007] In the description, the wiring to the light-receiving element is used as an example, but it is not limited to this. The same problem will occur for wiring for the direct current (DC) bias electrode that applies an electric field to the optical waveguide, or for electrical wiring in cases where other optical or electrical components such as semiconductor laser light sources are assembled together with the optical waveguide element.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 2017-187521 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] The problem to be solved by this invention is to provide an optical waveguide element that, while ensuring the effective area of ​​the chip on the optical waveguide substrate, suppresses the increase in the three-dimensional volume related to the optical waveguide element, thereby simplifying the manufacturing process related to electrical wiring. Furthermore, an optical modulator or optical transmitting device utilizing the aforementioned optical waveguide element is provided.

[0013] Technical means to solve the problem

[0014] In order to solve the aforementioned problems, the optical waveguide element, the optical modulator using the same, and the optical transmission device of the present invention have the following technical features.

[0015] (1) An optical waveguide element, comprising: an optical waveguide substrate having an optical waveguide formed thereon; and an auxiliary substrate disposed on the optical waveguide substrate and bonded to the optical waveguide substrate, wherein the optical waveguide element is characterized in that an electrical wiring is provided on the side of the auxiliary substrate opposite to the side bonded to the optical waveguide substrate.

[0016] (2) According to the optical waveguide element of (1), a portion of the electrical wiring is used as a signal line of a light-receiving element for detecting a portion of the light wave propagating in the optical waveguide, or as a DC line for applying a DC voltage to a control electrode disposed in the optical waveguide element.

[0017] (3) The optical waveguide element according to (1) or (2) is characterized in that a portion of the electrical wiring is used as wiring for electrical components connected to electrical components disposed outside the optical waveguide substrate.

[0018] (4) The optical waveguide element according to any one of (1) to (3) is characterized in that the end face of the auxiliary substrate is disposed flush with the end face of the optical waveguide substrate on which the input end and / or output end of the optical waveguide is disposed, and an optical component is disposed in contact with the end face of the optical waveguide substrate and the end face of the auxiliary substrate and is optically coupled to the input end and / or the output end.

[0019] (5) The optical waveguide element according to any one of (1) to (4) is characterized in that a light-receiving element for detecting a portion of the light wave propagating in the optical waveguide is disposed on the auxiliary substrate, and a portion of the electrical wiring is used as a signal line of the light-receiving element.

[0020] (6) The optical waveguide element according to any one of (1) to (5) is characterized in that the auxiliary substrate is made of a material that is transparent to visible light and has a dielectric constant of 15 or less.

[0021] (7) The optical waveguide element according to any one of (1) to (6) is characterized in that the electrical wiring is connected to the outside of the auxiliary substrate by a wire for electrical connection.

[0022] (8) An optical modulator, characterized in that it comprises: an optical waveguide element according to any one of (1) to (7); a housing for receiving the optical waveguide element; and an optical fiber for inputting or outputting optical waves relative to the optical waveguide.

[0023] (9) The optical modulator according to (8) is characterized in that a modulation electrode for modulating a light wave propagating in the optical waveguide is disposed on the optical waveguide substrate, and an amplification circuit for amplifying the modulation signal input to the modulation electrode is provided inside the frame.

[0024] (10) An optical transmitting device, characterized in that it comprises: an optical modulator according to (8) or (9); a light source for inputting light waves to the optical modulator; and a signal circuit for inputting a modulation signal to the optical modulator.

[0025] The effects of the invention

[0026] The optical waveguide element of the present invention can provide an optical waveguide element comprising: an optical waveguide substrate on which an optical waveguide is formed; and an auxiliary substrate disposed on and bonded to the optical waveguide substrate. In the optical waveguide element, electrical wiring is provided on the side of the auxiliary substrate opposite to the side bonded to the optical waveguide element. Therefore, while ensuring the effective area of ​​the chip on the optical waveguide substrate, the increase in the three-dimensional volume related to the optical waveguide element can be suppressed, thereby simplifying the manufacturing process related to the electrical wiring.

[0027] In addition, by utilizing the optical waveguide element, it is also possible to provide an optical modulator or optical transmitting device that has the aforementioned effect. Attached Figure Description

[0028] [ Figure 1 [ ] is a plan view illustrating existing optical waveguide components.

[0029] [ Figure 2 [ ] is a plan view illustrating another existing optical waveguide element.

[0030] [ Figure 3 [ ] is a plan view illustrating the optical waveguide element described in Patent Document 1.

[0031] [ Figure 4 [ ] is a plan view illustrating the first embodiment of the optical waveguide element of the present invention.

[0032] [ Figure 5 [This is an explanation] Figure 4 A cross-sectional view of an optical waveguide component.

[0033] [ Figure 6 [ ] is a plan view illustrating the electrical wiring of the optical waveguide element used in this invention.

[0034] [ Figure 7 [ ] is a cross-sectional view illustrating the electrical wiring of the optical waveguide element used in the present invention.

[0035] [ Figure 8 [ ] is a cross-sectional view illustrating a second embodiment of the optical waveguide element of the present invention.

[0036] [ Figure 9 [This is an explanation] Figure 8 A plan view of an optical waveguide element.

[0037] [ Figure 10 [ ] is a plan view illustrating a third embodiment of the optical waveguide element of the present invention.

[0038] [ Figure 11 [ ] is a plan view illustrating a fourth embodiment of the optical waveguide element of the present invention.

[0039] [ Figure 12 [ ] is a plan view illustrating the fifth embodiment of the optical waveguide element of the present invention.

[0040] [ Figure 13 [ ] is a plan view illustrating the sixth embodiment of the optical waveguide element of the present invention.

[0041] [ Figure 14 [ ] is a plan view illustrating the optical transmitting device of the present invention. Detailed Implementation

[0042] The optical waveguide element of the present invention, the optical modulator using the same, and the optical transmitting device thereof will be described in detail below.

[0043] For example, Figure 4 and Figure 5 As shown, the optical waveguide element of the present invention includes: an optical waveguide substrate 1 on which an optical waveguide 10 is formed; and an auxiliary substrate SS disposed on the optical waveguide substrate and bonded to the optical waveguide substrate. The optical waveguide element is characterized in that electrical wiring (EP11, EP21, EPG1, EL1, EL2, ELG, EP12, EP22, EPG2) is provided on the side of the auxiliary substrate SS opposite to the side bonded to the optical waveguide substrate.

[0044] As the substrate (optical waveguide substrate) 1 for the optical waveguide element used in the present invention, a substrate having an electro-optical effect can be used. Specifically, substrates made of lithium niobate (LN), lithium tantalate (LT), lead lanthanum zirconate titanate (PLZT), or substrates doped with MgO or the like can be used. Alternatively, these materials can be film-formed using vapor phase growth methods such as sputtering, evaporation, or chemical vapor deposition (CVD). Furthermore, a substrate formed by thin film processing of the electro-optical substrate after bonding it to other substrates can also be used. Moreover, substrates made of organic materials such as semiconductor substrates or ethylene oxide (EO) polymers can also be used.

[0045] As an optical waveguide 10, it is possible to utilize: an optical waveguide on a substrate (optical waveguide substrate) 1 on which a high refractive index material such as Ti is thermally diffused; an optical waveguide formed by a proton exchange method; and a rib-shaped optical waveguide 10 in which the portion of the substrate 1 corresponding to the optical waveguide is convex, by etching the substrate 1 outside the optical waveguide or forming grooves on both sides of the optical waveguide. Furthermore, by using a rib-shaped optical waveguide, Ti or the like can be diffused to the substrate surface using a thermal diffusion method or a proton exchange method, thereby further increasing the refractive index.

[0046] To achieve velocity matching between the microwave and light waves in the modulation signal, the thickness (maximum thickness) of the optical waveguide substrate (thin plate) 1 on which the optical waveguide 10 is formed is set to 10 μm or less, more preferably 5 μm or less, and even more preferably 1 μm or less. Furthermore, the height of the ribbed optical waveguide 10 (the height of the portion protruding from the planar waveguide) is set to 80% or less of the maximum thickness of the optical waveguide substrate, specifically 4 μm or less, more preferably 3 μm or less, and even more preferably 0.8 μm or less or 0.4 μm or less. Furthermore, the width of the ribbed optical waveguide 10 is set to 2 μm or less, or 1 μm or less.

[0047] To improve mechanical strength, a holding substrate 2 is bonded to the underside of the optical waveguide substrate 1, on which the optical waveguide is formed. The optical waveguide substrate 1 and the holding substrate 2 are directly bonded or fixed via an adhesive layer such as resin. As the holding substrate for direct bonding, it is preferable to have a lower refractive index than the optical waveguide or the substrate on which the optical waveguide is formed, but this is not a limitation. In the case of direct bonding, an intermediate layer such as a metal oxide or metal may be included in the bonding portion. In addition, the holding substrate 2 can preferably be made of a material with a thermal expansion coefficient close to that of the optical waveguide substrate 1, such as a substrate containing an oxide layer, such as crystal or glass. Furthermore, it is also possible to use the same LN substrate as the optical waveguide substrate 1, or simply silicon-on-insulator (SOI), lithium niobate-on-insulator (LNOI) composite substrate with a silicon oxide layer formed on a silicon substrate, or a composite substrate with a silicon oxide layer formed on an LN substrate. While maintaining the refractive index of substrate 2 higher than that of optical waveguide substrate 1, a layer with a refractive index lower than that of optical waveguide substrate 1 is provided between optical waveguide substrate 1 and holding substrate 2.

[0048] In addition, the substrate is not limited to being formed from a single substrate, but also includes a substrate that integrates multiple substrates by overlapping them.

[0049] To apply an electric field to the optical waveguide 10, a control electrode (not shown) is formed on the optical waveguide substrate 1. The control electrode comprises a multilayer structure including an upper electrode and a substrate layer. The upper electrode is made of a metal such as Au or Cu. The substrate layer is used to improve the adhesion between the optical waveguide substrate 1 and the upper electrode. The upper electrode is formed by covering the substrate layer using a method that combines electroplating of the substrate layer, electroless plating using a resist pattern, vapor deposition, or sputtering. The substrate layer is made of materials such as Ti, Nb, Ni, Cr, or Al, and is formed on the optical waveguide substrate by sputtering, vapor deposition, or other methods.

[0050] like Figure 4 and Figure 5 As shown, the optical waveguide element of the present invention is characterized in that electrical wiring is provided on the upper surface (the side of the auxiliary substrate SS opposite to the side of the optical waveguide substrate 1 that is disposed on the optical waveguide substrate 1 and bonded to the optical waveguide substrate 1).

[0051] exist Figure 4 and Figure 5 In this configuration, the auxiliary substrate SS also serves to increase the bonding area when bonding the optical component OP to the optical waveguide substrate 1. The end face of the auxiliary substrate SS is aligned with the end face of the optical waveguide substrate 1, on which the input or output end of the optical waveguide 10 is disposed. An optical component optically bonded to the input or output end is disposed in contact with both the end face of the optical waveguide substrate and the end face of the auxiliary substrate. The optical waveguide substrate 1 (including the holding substrate 2) and the auxiliary substrate SS are bonded to the optical component OP using adhesive AD1. Furthermore, the optical waveguide substrate 1 and the auxiliary substrate SS are bonded using adhesive AD2, and the optical waveguide substrate 1 is bonded to the light-receiving elements (PD1, PD2) using adhesive AD3. Alternatively, the optical component OP may not be bonded to the auxiliary substrate SS.

[0052] The electrical wiring configured on the auxiliary substrate SS uses metals such as Au or Cu, similar to the control electrodes. When the adhesion between these metals and the auxiliary substrate is weak, a substrate layer can be provided in the same manner as the control electrodes.

[0053] Figure 6 This is a plan view illustrating a portion of the electrical wiring formed on the auxiliary substrate SS. The electrical wiring includes portions (EP11, EP21, EPG1, EP12, EP22, EPG2) configured for connecting conductors (W11, W21, WG1, W12, W22, WG2), and wiring portions (EL1, EL2, ELG) connecting the electrode pads to each other. Of course, as will be described later... Figure 11The electrode pad EP1 is an electrode pad without wiring, but the wiring of the electrode pad EP1, which is connected to multiple wires (W11, W12), is also included in the electrode wiring of the present invention.

[0054] about Figure 6 The dimensions (width H × width I) of the electrode pads (EP11, etc.) are set to be 100 μm or more, ensuring the degree of alignment between the wires and the electrode pads during wire bonding operations can be reliably implemented. In addition, the width J of the wiring section (EL1, etc.) needs to be 10 μm or more, preferably 30 μm or more, to avoid defects such as wire breakage.

[0055] The thickness K of electrical wiring (electrode pads, wiring section) (refer to) Figure 7 The thickness is set to 300 nm or more to reliably bond the wires to the electrode pads in wire bonding operations and to ensure that the thickness is low enough to prevent wire breakage.

[0056] Figure 5 The height G of the loop of the wire (W12, etc.) in wire bonding also depends on the thickness of the auxiliary substrate SS or the thickness of the light-receiving element (PD1, PD2). Assuming that it is used as an optical component OP for bonding to a lens, the thickness D of the auxiliary substrate SS is set to 500 μm or more to ensure sufficient bonding area. Furthermore, the height G of the loop, which prevents the wire from becoming straight and from tilting, is set to a range of 400 μm or more and 750 μm or less.

[0057] The material used as the auxiliary substrate SS is preferably a material that is transparent to light waves propagating in the optical waveguide, such as a material that is transparent to visible light, and has a dielectric constant of 15 or less. Materials with low dielectric constants also have the advantages of excellent insulation and low dielectric loss. Specific materials may be inorganic metal oxides or resins, such as glass, quartz, and alumina.

[0058] exist Figure 4 and Figure 5 In this method, by utilizing the auxiliary substrate SS for attaching and fixing optical components (OP), there is no need to prepare a new relay substrate, and it is also a component previously used for optical waveguide elements. Therefore, there is neither an increase in the number of parts nor any complication to the previous manufacturing process. Figure 4As shown, the light receiving elements (PD1, PD2) are electrically connected by connecting pins (PS1, PS2, PG). Specifically, in the light receiving element (PD1), two wiring systems are connected from the signal connecting pin (PS1) and the grounding connecting pin (PG2) through various wires (W11, WG1), electrode pads (EP11, EPG1), wiring sections (EL1, ELG), electrode pads (EP12, EPG2), and wires (W12, WG2).

[0059] In addition, such as Figure 4 As shown, there is a possibility that the adhesive AD1 may be exposed and extend towards the electrical wiring (EP21, EL2, etc.). The distance C from the end of the auxiliary substrate to the electrical wiring is preferably ensured to be 200 μm or more. In addition, an increase in the width A of the auxiliary component SS also leads to a reduction in the effective area of ​​the chip. It is preferable to set the width A to 1000 μm or less.

[0060] The distance B between the light-receiving elements (PD1, PD2) disposed on the optical waveguide substrate 1 and the auxiliary substrate SS also depends on the size of the light-receiving elements or the shape of the optical waveguide 10 arrangement (position of the wave combiner, etc.). However, when the step difference between the surface of the light-receiving elements (PD1, PD2) and the auxiliary substrate SS is in the range of 350 μm to 500 μm, it is set to 700 μm or less, more preferably 650 μm or less, and even more preferably 600 μm or less. In addition, it is set to 400 μm or more to avoid sharp bending of the wires.

[0061] The above description shows an example of using a bonding member for optical components (OP) as an auxiliary substrate (SS), but it is not limited to this. It is also possible to utilize [other components] based on the auxiliary substrate (SS1). Figure 12 The auxiliary substrate SS2 shown is for relay purposes. In addition, in cases where the light-receiving element is separated from the auxiliary substrate SS1, the wiring of the auxiliary substrate SS1 may be omitted, and only the auxiliary substrate SS2, which is directly electrically connected to the light-receiving element (PD1, PD2), may be used.

[0062] Figure 8 and Figure 9 This is a diagram illustrating a second embodiment of the optical waveguide element of the present invention. (See diagram below.) Figure 8 and Figure 9 As shown, a light-receiving element PD is disposed on the upper surface of the auxiliary substrate SS to detect a portion of the light wave propagating in the optical waveguide 10. Furthermore, a portion of the electrical wiring (EP, EL) disposed on the upper surface of the auxiliary substrate SS is used as a signal line for the light-receiving element PD. The light-receiving element PD is attached to the auxiliary substrate SS by an adhesive AD4.

[0063] In order to detect a portion of the light wave propagating in the optical waveguide 10 using the light-receiving element PD, a grating GT is disposed close to the optical waveguide 10. The grating GT can be constructed as an additional component or can be formed by processing on the lower surface of the auxiliary substrate SS. Alternatively, instead of the grating, part or all of the auxiliary component can be replaced with a component having a refractive index higher than that of the optical waveguide 10.

[0064] As in the second embodiment, by arranging the light-receiving element PD on the auxiliary substrate SS, the length of the wire W can be shortened, thereby ensuring a larger effective area of ​​the optical waveguide substrate (chip).

[0065] Figure 10 This diagram illustrates a third embodiment of the optical waveguide element of the present invention. A semiconductor laser (light source LD) is disposed adjacent to the optical waveguide substrate (chip) as a light source. The light source LD and the optical waveguide substrate 1 may be connected as needed. When an electrical component such as the light source LD is disposed outside the optical waveguide substrate 1, electrical wiring (EP11, EP21, EL1, EL2, EP12, EP22) disposed on an auxiliary substrate SS can also be used as part of the wiring for powering or transmitting signals to the electrical component.

[0066] Figure 11 This is a diagram illustrating a fourth embodiment of the optical waveguide element of the present invention. It shows an example of using a portion of the electrical wiring on the auxiliary substrate SS when supplying DC bias to control electrodes, particularly DC bias electrodes (not shown), disposed on the optical waveguide substrate. Symbols DCP1 and DCP2 denote electrode pads connected to the DC bias electrodes disposed on the optical waveguide substrate. DC bias is supplied to these electrode pads from externally supplied DC bias connection pins (P1, P2) via two wiring systems (wire W11 → electrode pad EP1 → wire W12, wire W21 → electrode pad EP21 → wiring portion EL → electrode pad EP22 → wire W22).

[0067] As shown in the electrode pad (EP1), in the optical waveguide element of the present invention, the electrical wiring formed on the auxiliary substrate SS also includes electrical wiring that excludes the wiring portion from the electrode pad. Furthermore, although not shown, the electrical wiring of the auxiliary substrate can also be electrically connected using wires instead of the wiring portion.

[0068] Figure 12This diagram illustrates the fifth embodiment of the optical waveguide element of the present invention. In the electrical connection from the connecting pins (PS1, PS2, PG) to the light-receiving element (PD1, etc.), in addition to the auxiliary substrate SS1 used for bonding optical components, a relay-specific auxiliary substrate SS2 disposed on the optical waveguide substrate 1 can also be used. Regarding the light-receiving element PD1, the electrical connection from the connecting pins (PS1, PG) is made using two wiring systems (wire W11 → electrode pad EP11 → wiring portion EL11 → electrode pad EP12 → wire W12 → electrode pad EP13 → wiring portion EL12 → electrode pad EP14 → wire W13, wire WG1 → electrode pad EPG1 → wiring portion ELG1 → electrode pad EPG2 → wire WG2 → electrode pad EPG3 → wiring portion ELG2 → electrode pad EPG4 → wire WG3).

[0069] When a relay-dedicated auxiliary substrate SS2 is disposed on the optical waveguide substrate 1, it is preferable to configure it so that the light waves propagating in the optical waveguide 10 are not absorbed or scattered, or that the electric field formed by the electrical wiring applied to the optical waveguide does not affect the modulated light. For this purpose, it is necessary to configure the electrical wiring so that it is not disposed directly above the optical waveguide. Even if it is directly above the optical waveguide, if the electrical wiring is arranged orthogonally to the extension direction of the optical waveguide, the influence of the electric field formed by the electrical wiring on the optical waveguide can be suppressed. Furthermore, in the previous descriptions, the electrical wiring was formed on the upper surface of the auxiliary substrates SS, SS1, SS2, etc., but a portion of the electrical wiring may also be formed on the side surface or bottom surface other than the upper surface. Additionally, as... Figure 13 As shown, when the distance between the connecting pins (PS1, PG) and the light-receiving element (PD1) is short, they can be directly connected via wires (W1, WG). When the distance between the connecting pins (PS2, PG) and the light-receiving element (PD2) is long, the wiring system can also be connected via the electrode pads (EP21, EP22, PGG1, EPG2) or wiring sections (EL2, ELG) on the auxiliary substrate SS.

[0070] Next, examples of applying the optical waveguide element of the present invention to optical modulators or optical transmitting devices will be described. Hereinafter, an optical waveguide element having a nested optical waveguide will be described, but the present invention is not limited thereto, and can also be applied to HB-CDM, optical phase modulators, optical modulators with polarization combining function, or optical modulators integrating more or fewer Mach-Zehnder type optical waveguides, bonding devices to optical waveguide substrates containing other materials such as silicon, and devices for sensor applications, etc.

[0071] like Figure 14As shown, the optical waveguide element includes an optical waveguide 10 formed on an optical waveguide substrate 1, and electrodes (not shown) such as modulation electrodes for modulating light waves propagating in the optical waveguide 10, the substrate 1 being housed within a frame CA. Furthermore, by providing an optical fiber (F) relative to the input / output light waves of the optical waveguide, an optical modulator MD can be constructed. Figure 14 In this method, an optical fiber (F) is introduced into the frame through a through-hole in the side wall of the frame CA, and the optical waveguide substrate 1 is directly bonded to the optical fiber. Alternatively, the light wave L1 incident from the optical fiber F or the light wave L2 emitted from the optical fiber F can be optically bonded to the optical waveguide 10 within the optical waveguide substrate 1 via an optical block or lens barrel including an optical lens, a polarization combiner, etc. In addition, in order to stably bond with optical components such as optical fibers or optical blocks, the auxiliary member SS is arranged overlapping the optical waveguide substrate 1 along the end face of the substrate 1.

[0072] By connecting the electronic circuitry (digital signal processor, DSP) that outputs the modulation signal S0 to modulate the optical modulator MD to the optical modulator MD, an optical transmitting device OTA can be constructed. To obtain the modulation signal S applied to the optical waveguide element, operation can be performed even by amplifying the modulation signal S0 output from the digital signal processor DSP. Therefore, in Figure 14 In this configuration, a driver circuit (DRV) is used to amplify the modulated signal. The DRV or digital signal processor (DSP) can be configured either outside or inside the housing (CA). In particular, configuring the DRV inside the housing further reduces propagation loss of the modulated signal originating from the driver circuit. If the modulated signal degradation is minimal, a DRV is unnecessary, and the DSP can be used directly for modulation of the optical modulator (MD).

[0073] The input light L1 to the optical modulator MD can be supplied from outside the optical transmitter OTA, but it can also be... Figure 10 The semiconductor laser LD shown is integrated as a light source into the optical transmitting device OTA. The output light L2, modulated by the optical modulator MD, is output to the outside through the optical fiber F.

[0074] Industrial availability

[0075] As explained above, according to the present invention, an optical waveguide element can be provided that, while ensuring the effective area of ​​the chip on the optical waveguide substrate, suppresses the increase in the three-dimensional volume related to the optical waveguide element, thereby simplifying the manufacturing processes related to electrical wiring. Furthermore, an optical modulator or optical transmitting device utilizing the aforementioned optical waveguide element can be provided.

[0076] Explanation of icon numbers

[0077] 1: Optical waveguide substrate (thin plate, film)

[0078] 2: Maintain substrate

[0079] 10: Optical waveguide

[0080] SS: Auxiliary substrate

[0081] EP11, EP12, EPG1, EPG2, etc.: Electrical wiring (electrode pads)

[0082] EL1, ELG, etc.: Electrical wiring (wiring section)

[0083] PD1, PD2: Light receiving elements

[0084] OP: Optical components

[0085] F: Optical fiber

[0086] CA: Frame

[0087] MD: Optical Modulator

[0088] DRV: Driver circuit

[0089] DSP: Digital Signal Processor

[0090] OTA: Optical Transmission Device

Claims

1. An optical waveguide element comprising: An optical waveguide substrate in which an optical waveguide is formed; and a sub substrate disposed on the optical waveguide substrate and joined to the optical waveguide substrate, the optical waveguide element characterized in that An electrical wiring is provided on a surface of the sub substrate opposite to the surface joined to the optical waveguide substrate.

2. The optical waveguide element according to claim 1, characterized by A part of the electrical wiring is used as a signal line of a light receiving element that detects a part of an optical wave propagating in the optical waveguide, or a direct current line that applies a direct current voltage to a control electrode disposed in the optical waveguide element.

3. The optical waveguide element according to claim 1, wherein A part of the electrical wiring is used as an electrical element wiring that connects to an electrical element provided outside the optical waveguide substrate.

4. The optical waveguide element according to claim 1, characterized in that The end surface of the sub substrate is disposed in alignment with an end surface of the optical waveguide substrate in which an input end portion and / or an output end portion of the optical waveguide is disposed, An optical member that optically combines with the input end portion and / or the output end portion is disposed in contact with the end surface of the optical waveguide substrate and the end surface of the sub substrate.

5. The optical waveguide element according to claim 1, wherein A light receiving element that detects a part of an optical wave propagating in the optical waveguide is disposed in the sub substrate, and a part of the electrical wiring is used as a signal line of the light receiving element.

6. The optical waveguide element according to claim 1, wherein The sub substrate is composed of a material that is transparent to visible light and has a dielectric constant of 15 or less.

7. The optical waveguide element according to claim 1, wherein A lead wire for electrical connection is connected to the sub substrate from outside.

8. An optical modulator, comprising Including: The optical waveguide element according to claim 1; A frame that houses the optical waveguide element; and An optical fiber that inputs or outputs an optical wave to or from the optical waveguide.

9. The optical modulator of claim 8, wherein, A modulation electrode for modulating an optical wave propagating in the optical waveguide is disposed in the optical waveguide substrate, An amplification circuit that amplifies a modulation signal input to the modulation electrode is provided inside the frame.

10. An optical transmitting device, characterized in that... Having: the optical modulator according to claim 8; A light source that inputs an optical wave to the optical modulator; and A signal circuit that inputs a modulation signal to the optical modulator.

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