Optical signal processing device, optical integrated circuit chip, and method for producing optical signal processing device

Abstract

The present invention comprises: a chip 22 including a substrate 22a and a phase shifter 222 that controls an optical switch which is formed on the substrate 22a; a chip 21 including a substrate 21a and a phase shifter 212 that controls an optical switch which is formed on the substrate 21a; and a wire bonding substrate 25 including an electrode 254 and a common electrode 255 for supplying power to the chips 21 and 22, wherein an optical signal processing device is configured by the chip 22 including an electrode 226 and wiring 223 for connecting the electrode 254 and the common electrode 255 to the phase shifter 222, and an electrode 224 and the wiring 223 for connecting the electrode 254 and the common electrode 255 to a phase shifter 211.

Description

Optical signal processing device, optical integrated circuit chip, and method for manufacturing optical signal processing device

[0001] The present disclosure relates to an optical signal processing device, an optical integrated circuit chip, and a method for manufacturing an optical signal processing device, and more particularly to an optical signal processing device, an optical integrated circuit chip, and a method for manufacturing an optical signal processing device used in optical communications.

[0002] In optical communications, optical switches that switch optical paths and gain equalizers that correct the wavelength dependency of light intensity can be realized using interferometers composed of optical waveguides. A heater, for example, is used as a phase shifter in such optical elements. A heater-based phase shifter heats the waveguide by passing an electric current through it, controlling the refractive index of the waveguide and the phase of light passing through the waveguide through the thermo-optic effect. The phase shifter receives power via electrical wiring. A simple connection between the phase shifter and a power supply can be achieved by forming electrical wiring within the surface of the optical waveguide chip and connecting it to a wire bonding substrate using electrode pads and wire bonding. This configuration can simplify the structure of the optical waveguide chip. This configuration is disclosed, for example, in Non-Patent Document 1.

[0003] Optical waveguide elements such as optical switches and gain equalizers are sometimes configured by integrating multiple elements onto a single chip in order to reduce manufacturing costs and module size. This allows not only the integration of optical waveguide elements but also the connection of electrical wiring and electrode pads corresponding to all phase shifters to a single wire-bonding substrate by wire bonding. Such a configuration is described, for example, in Non-Patent Document 1.

[0004] HIMENO, Akira; KATO, Kuniharu; MIYA, Tetsuo. Silica-based planar lightwave circuits. IEEE Journal of selected topics in quantum electronics, 1998, 4.6: 913-924.

[0005] However, when multiple optical waveguide elements are integrated on one chip, if all of the optical waveguide elements do not operate normally, the chip becomes defective, which poses a problem of reduced yield in chip manufacturing.

[0006] To solve the above problems, it is conceivable to separate optical waveguide elements into multiple chips rather than integrating many optical waveguide elements into a single chip. Integrating optical waveguide elements into multiple chips requires the provision of multiple wire-bonding substrates, or the placement of chips on both sides of a single wire-bonding substrate. A configuration with multiple wire-bonding substrates results in a larger module consisting of chips and wire bonding. Furthermore, placing chips on both sides of a wire-bonding substrate results in the two chips being oriented in opposite directions, necessitating the routing of optical fibers connected to the optical waveguides, again resulting in a larger module. Furthermore, it is conceivable to design the wire-bonding substrate connected to one side of the wire-bonding substrate differently and align the orientation of the two chips. However, in this case, chips with different designs would be used to manufacture the module, reducing chip utilization efficiency.

[0007] The present disclosure has been made in view of the above points, and relates to an optical signal processing device, an optical integrated circuit chip, and a method for manufacturing an optical signal processing device that is advantageous for miniaturizing a module and has high component utilization efficiency.

[0008] In order to solve the above problems, one aspect of the optical signal processing device of the present disclosure includes a first optical integrated circuit chip including a first substrate and a first passive element that controls an optical element formed on the first substrate, a second optical integrated circuit chip including a second substrate and a second passive element that controls an optical element formed on the second substrate, and an electric substrate having a power supply electrode that supplies power to the first optical integrated circuit chip and the second optical integrated circuit chip, wherein the first optical integrated circuit chip includes a first electrode portion that connects the power supply electrode and the first passive element, and a second electrode portion that connects the power supply electrode and the second passive element.

[0009] One aspect of the optical integrated circuit chip disclosed herein is an optical integrated circuit chip comprising a substrate and a passive element that controls an optical element formed on the substrate, and includes a first electrode portion that connects a power supply electrode formed on an electrical substrate to the passive element, and a second electrode portion that connects the power supply electrode to another passive element formed on another substrate different from the substrate.

[0010] One aspect of the method for manufacturing an optical signal processing device disclosed herein is a method for manufacturing an optical signal processing device by connecting a plurality of optical integrated circuit chips and an electric substrate, and includes a step of electrically connecting one of the plurality of optical integrated circuit chips to the electric substrate, and a step of electrically connecting another optical integrated circuit chip to the electric substrate via the optical integrated circuit chip.

[0011] According to the above aspects, it is possible to provide an optical signal processing device, an optical integrated circuit chip, and a method for manufacturing an optical signal processing device, which are advantageous for miniaturizing a module and have high component utilization efficiency.

[0012] FIG. 1 is a diagram for explaining an optical switch using a Mach-Zehnder interferometer. FIG. 2 is a top view for explaining an optical signal processing device according to a first embodiment of the present disclosure. FIG. 3 is a diagram for explaining an example in which the optical signal processing device shown in FIG. 2 further includes another chip. FIG. 4 is a top view for explaining an optical signal processing device that is a modified example of the first embodiment. FIG. 5 is a schematic diagram showing a gain equalizer using a lattice filter circuit. FIG. 6 is a top view for explaining the optical signal processing device according to the first embodiment of the present disclosure. (a) and (b) are diagrams illustrating comparative examples of the first and second embodiments.

[0013] Hereinafter, a first embodiment and a second embodiment of the present disclosure (hereinafter also collectively referred to as "the present embodiment") will be described with reference to the drawings. The drawings of the present embodiment are intended to explain the configuration, arrangement, action, function, effects, and technical concept of the present disclosure, and are not intended to limit the specific shape or configuration of the present disclosure.

[0014] First Embodiment FIG. 1 is a diagram illustrating a one-input, two-output (1 × 2) optical switch using a Mach-Zehnder interferometer. Power is supplied to a phase shifter 11, which serves as a heater, via electrical wiring 12. The optical waveguide, whose phase is controlled by the phase shifter, includes an input waveguide 151, an arm waveguide 154, and an output waveguide 152, constituting a 3 dB coupler 153. Light input from the input waveguide 151 is branched to the arm waveguide 154 via the 3 dB coupler 153 and output again via the 3 dB coupler 153. At this time, the phase of the passing light is controlled by the phase shifter 11 disposed in the arm waveguide 154, thereby changing the interference state at the second 3 dB coupler 153. This optical switch can control the output intensity to two output waveguides 152 and operates as an optical switch by selectively controlling the intensity to be transmitted to only one of the output waveguides 152.

[0015] Fig. 2 is a top view for explaining the optical signal processing device of the first embodiment. In Fig. 2, the optical waveguide shown in Fig. 1 is omitted. Also, Fig. 1 shows an example in which two phase shifters are provided, but Fig. 2 shows an example in which three phase shifters are provided.

[0016] The optical signal processing device of this embodiment includes chip 22, which is a first optical integrated circuit chip, and chip 21, which is a second optical integrated circuit chip. Chip 22 includes substrate 22a, which is a first substrate, an optical switch formed on substrate 22a and configured with an optical waveguide (FIG. 1), which is a first optical element, and phase shifter 222, which controls the optical switch. Chip 21 includes substrate 21a, which is a second substrate, and phase shifter 212, which controls the optical switch, which is a second optical element, formed on substrate 21a. Phase shifters 212 and 222 are passive elements that consume supplied power.

[0017] The optical signal processing device also includes a wire bonding substrate 25 having a common electrode 258 and an electrode 256 that supply power to the chips 21 and 22. The wire bonding substrate 25 corresponds to the electric substrate in the first embodiment. The common electrode 258 and the electrode 256 also function as the power supply electrodes in the first embodiment.

[0018] The chip 22 includes a first electrode portion connecting the electrode 256 and the phase shifter 222, and a second electrode portion connecting the electrode 256 and the phase shifter 212. In the first embodiment shown in FIG. 2 , two electrodes 226 and the wiring 223 connecting the electrodes 226 form the first electrode portion, and two electrodes 224 and the wiring 223 connecting the electrodes 224 form the second electrode portion. That is, in the chip 22, the electrode 226 is connected to its own phase shifter 222, and the electrode 224 is connected to the phase shifter 214 of another chip 21. The electrode 228 connected to the common electrode 258 is connected to the electrode 218 of the chip 21. The electrodes are connected to each other by wire bonding using wires 2.

[0019] Furthermore, the chips 21 and 22 each include a fiber array 211 connected to the optical waveguide, and a fiber array 221 connected to the optical waveguide. The fiber array 211 includes an optical fiber 211a and a connection portion 211b. The fiber array 221 includes an optical fiber 221a and a connection portion 221b.

[0020] 2, the chips 21 and 22 are connected to one side of a single wire bonding substrate, so the fiber arrays 211 and 221 of the chips 21 and 22 are positioned in the same direction, facilitating the routing of the optical fibers and preventing the module comprising the wire bonding substrate 25 and the chips 21 and 22 from becoming larger. Furthermore, chips with the same design can be used for the chips 21 and 22, i.e., chips with phase shifters and electrodes of the same shape and positioned in the same positions. This facilitates component stocking and management, and improves component utilization efficiency.

[0021] Furthermore, the first embodiment is not limited to a configuration in which two chips 21 and 22 are connected to the wire bonding substrate 25. In the first embodiment, a larger number of chips can be connected to the wire bonding substrate. FIG. 3 shows an example in which a chip 23 is connected in addition to the chips 21 and 22. In FIG. 3, the same components as those shown in FIG. 2 are denoted by the same reference numerals, and some of the description will be omitted. Also, in FIG. 3, as in FIG. 2, the optical waveguide shown in FIG. 1 is not shown.

[0022] The optical signal processing device shown in FIG. 3 includes a wire bonding substrate 25, chips 21, 22, and chip 23. Chip 23 includes a substrate 23a, which is a third substrate, and a phase shifter 232 that controls an optical switch formed on substrate 23a. The electrode portion of chip 23 is composed of an electrode 236 and wiring 233, an electrode 234 and wiring 233, and an electrode 238 and wiring 233. Electrode 236 is connected to phase shifter 232. Electrode 214 of chip 21 is connected to phase shifter 232. Electrode 214 and wiring 213 constitute a third electrode portion. Electrode 224 and wiring 223 of chip 22 are connected to electrode 214, which constitutes the third electrode portion. Electrode 224 and wiring 223 constitute a fourth electrode portion.

[0023] In the first embodiment configured as described above, the chip 21 connects the chips 22 and 23. The chip 23 is connected to the wire bonding substrate 25 via the electrodes 236 and 214, the wiring 213, the electrode 224, and the wiring 223, and receives a supply of power. Furthermore, the chip 23 includes a fiber array 231, and the fiber array 231 includes an optical fiber 231a and a connection portion 231b.

[0024] In this way, in the first embodiment, by increasing the number of electrode portions (second electrode portions) of each chip that are not connected to the phase shifter, more chips can be connected to the wire bonding substrate.

[0025] (Manufacturing Method) The optical signal processing device of the first embodiment described above is manufactured by connecting chips 21 and 22 to wire bonding substrate 25. This manufacturing method includes a step of electrically connecting chip 22 of the multiple chips to wire bonding substrate 25, and a step of electrically connecting another chip 21 to wire bonding substrate 25 via the previous chip 22. Furthermore, the manufacturing method of the first embodiment is not limited to this configuration, and chip 22 may be connected to chip 21 first, and then chips 21 and 22 may be connected to the wire bonding substrate.

[0026] (Modification) Next, a modification of the first embodiment will be described. FIG. 4 is a top view illustrating an optical signal processing device that is a modification of the first embodiment. The optical signal processing device shown in FIG. 4 includes a wire bonding substrate 25, a chip 24 directly connected to the wire bonding substrate 25, and a chip 26 connected to the wire bonding substrate 25 via the chip 24. The chip 24 has a substrate 24a and a phase shifter 242 formed on the substrate 24a, and includes an electrode 246 connected to the phase shifter 242 and electrodes 244 and 248 connected to the chip 26. The electrodes 244, 246, and 248 are all connected to an electrode 254 of the wire bonding substrate 25. The chip 26 includes a phase shifter 262 formed on the substrate 26a, an electrode 266 connected to the phase shifter 262, and an electrode 264 that is not connected to the phase shifter 262 and may be connected to another chip.

[0027] The chip 24 includes a fiber array 241 including optical fibers 241a and connection portions 241b. The chip 26 includes a fiber array 261 including optical fibers 261a and connection portions 261b. The optical signal processing device of Fig. 4 differs from the first embodiment in that the connection surface between the fiber array 241 and the substrate 24a and the connection surface between the fiber array 261 and the substrate 26a are arranged on a straight line in a top view. Fig. 4 shows an example in which the connection surface between the fiber array 241 and the substrate 24a and the connection surface between the fiber array 261 and the substrate 26a are on a straight line L.

[0028] To achieve this configuration, in this modification, the electrode portion not connected to the phase shifter is configured as follows. That is, in chip 24, electrodes 244 and 248 are electrodes not connected to phase shifter 242. Wiring 243 connects these electrodes to form the electrode portion. In part of the electrode portion, wiring 243a connects electrodes 248 together in a linear manner. Another part of the electrode portion includes two electrodes 244 and wiring 243 connecting electrodes 244 together, and wiring 243 includes lead-out portion 243b directly connected to electrode 244, routing portion 243c extending in a direction intersecting lead-out portion 243b, and terminal portion 243d extending in the same direction as lead-out portion 243b. Similarly, in chip 26, in part of the electrode portion, wiring 263a connects electrodes 268 together in a linear manner. In addition, another part of the electrode portion includes two electrodes 264 and wiring 263 connecting the electrodes 264 to each other, and the wiring 263 includes an extension portion 263b directly connected to the electrode 264, a routing portion 263c extending in a direction intersecting the extension portion 263b, and an end portion 263d extending in the same direction as the extension portion 263b.

[0029] In this way, the positions of the wiring paths and electrodes can be shifted in one direction of the chip by any length (determined by the length of the routing portion). By appropriately setting the shift amount, the end faces of the wire bonding substrate 25 and the substrates 24a and 26a can be aligned, thereby further reducing the size of the optical signal processing device module. In addition, the workability of connecting the fiber arrays 241 and 261 can be improved.

[0030] Second Embodiment In the first embodiment, an example in which an optical waveguide constitutes an optical switch has been described. However, the present disclosure is not limited to examples in which the optical element is applied to an optical switch. FIG. 5 is a schematic diagram showing a gain equalizer using a lattice filter circuit. The lattice filter circuit is configured by connecting multiple Mach-Zehnder interferometers and, similar to the Mach-Zehnder interferometer shown in FIG. 1 , controls the refractive index of the optical waveguide and the phase of the optical signal passing through the optical waveguide. The optical waveguide includes an input waveguide 151, an arm waveguide 154, and an output waveguide 152, and the arm waveguide 154 is heated by a phase shifter 11 and electrical wiring 12. Before and after the phase shifter 11, the optical waveguides form a coupler 153.

[0031] Fig. 6 is a top view illustrating an optical signal processing device according to a second embodiment. Similar to Figs. 2 to 4, Fig. 6 omits the illustration of optical waveguides. In the case of a lattice filter circuit, as shown in Fig. 5, electrical wiring must be provided for multiple stages of phase shifters, and the pads are also divided into multiple stages. Therefore, in the optical signal processing device of Fig. 6, multiple sets of phase shifters and electrode units, as described in the first embodiment, are arranged on each of chips 27 and 28, and chips 27 and 28 are further connected to wire bonding substrate 25 by wires 2.

[0032] 6, chip 27 includes, on a substrate, phase shifters 272, electrodes 274, 276, and 278, and wiring 273 connecting the electrodes. Three phase shifters 272 and a total of 11 electrodes 274, 276, and 278 form a unit, and these units are formed in multiple stages in the longitudinal direction of chip 27. Similarly, chip 28 includes three phase shifters 282 and a total of 11 electrodes 284, 286, and 288 form a unit, and these units are formed in multiple stages in the longitudinal direction of chip 27.

[0033] Furthermore, the first and second embodiments are not limited to being applied to optical switches and lattice filter circuits as optical elements. Other optical elements to which the present disclosure can be applied may include at least one of a variable optical attenuator (VOA) and a lattice filter. Furthermore, while the first and second embodiments use a phase shifter as an example of a passive element (driven element), other elements such as a variable attenuation element may also be used.

[0034] (Comparative Example) Next, a comparative example to the first and second embodiments described above will be described. FIG. 7( a) shows an example in which chips 71 and 72 are provided on both sides of a wire-bonding substrate 76. The wire-bonding substrate 76 has a common electrode 758 and an electrode 756 along two sides of the substrate, respectively. The chip 71 includes a phase shifter 712, an electrode 718, and wiring 713, while the chip 72 includes a phase shifter 722, an electrode 728, and wiring 723. The chip 72 is not connected to the phase shifter, and does not have an electrode for connecting to another substrate. As is clear from the diagram, in the configuration of FIG. 7, the fiber array 711 of the chip 71 and the fiber array 721 of the chip 72 are arranged in opposite directions. Therefore, the configuration of FIG. 7( a) complicates the extraction of optical fibers, which is disadvantageous for miniaturizing the module.

[0035] 7(b) shows an example in which two wire bonding substrates 25 are provided when optical elements (not shown) and phase shifters are distributed among multiple chips. Each of the two wire bonding substrates 25 has a common electrode 758 and an electrode 756, and is connected to chip 71 or chip 72. While this configuration overcomes the drawback of the configuration in FIG. 7(a), in that the fiber arrays 711 and 721 are connected in opposite directions, the increased number of wire bonding substrates 25 results in a larger module.

[0036] The optical signal processing devices of the first and second embodiments distribute optical elements, phase shifters, and even electrodes and wiring across multiple substrates, thereby avoiding a decrease in manufacturing yield of the optical signal processing device due to the integration of multiple circuits on a single substrate. Furthermore, compared to the configurations of Figures 7(a) and 7(b), the first and second embodiments align the connection direction of the fiber arrays between multiple chips, making it easier to route the optical fibers and reducing the module size. Furthermore, the configurations of the first and second embodiments connect two chips to a single wire-bonding substrate, preventing the module from becoming too large.

[0037] 2 Wire 11 Phase shifter 12 Electrical wiring 21, 22, 23, 24, 26, 27, 28, 71, 72 Chip 21a, 22a, 23a, 24a, 26a Substrate 25, 26 Wire bonding substrate 151 Input waveguide 152 Output waveguide 153 Coupler 154 Arm waveguide 211, 221, 231, 241, 262, 711, 721 Fiber array 211a, 221a, 231a, 241a, 261a Optical fiber 211b, 221b, 231b, 241b, 261b Connection portion 212, 222, 232, 242, 262, 272, 282, 712, 722 Phase shifter 213, 223, 243, 243a, 263, 263a, 713, 723 Wiring 214, 216, 224, 226, 234, 236, 244, 246, 248, 254, 264, 266, 268, 274, 276, 278, 284, 286, 288, 718, 728, 756 Electrode 243b, 263b Lead-out portion 243c, 263c Leading portion 243d, 263d Termination portion 255, 758 Common electrode

Claims

1. An optical signal processing device comprising: a first optical integrated circuit chip comprising a first substrate and a first passive element that controls an optical element formed on the first substrate; a second optical integrated circuit chip comprising a second substrate and a second passive element that controls an optical element formed on the second substrate; and an electrical substrate having a power supply electrode that supplies power to the first optical integrated circuit chip and the second optical integrated circuit chip, wherein the first optical integrated circuit chip comprises a first electrode portion that connects the power supply electrode to the first passive element, and a second electrode portion that connects the power supply electrode to the second passive element.

2. An optical signal processing device according to claim 1, comprising a third optical integrated circuit chip having a third substrate and a third passive element that controls an optical element formed on said third substrate, said second optical integrated circuit chip having a third electrode portion that connects with said third passive element, and said first optical integrated circuit chip having a fourth electrode portion that connects said power supply electrode and said third electrode portion.

3. An optical signal processing device according to claim 1, comprising an optical fiber connected to the optical element, wherein the connection surface between the optical fiber and the first substrate and the connection surface between the optical fiber and the second substrate are arranged on a straight line when viewed from above.

4. An optical signal processing device as described in claim 3, wherein the second electrode portion includes two electrode pads and wiring connecting the electrode pads, and a portion of the wiring of the second electrode portion connects the electrode pads in a straight line, and another portion of the wiring includes an extraction portion directly connected to the electrode pads, a routing portion extending in a direction intersecting the extraction portion, and a terminal portion extending in the same direction as the extraction portion.

5. The optical signal processing device according to claim 1, wherein the optical element includes at least one of an optical switch array, a variable optical attenuator, and a grating filter.

6. An optical integrated circuit chip comprising a substrate and a passive element for controlling an optical element formed on the substrate, the optical integrated circuit chip including: a first electrode portion connecting a power supply electrode formed on an electrical substrate to the passive element; and a second electrode portion connecting the power supply electrode to another passive element formed on a substrate different from the substrate.

7. A method for manufacturing an optical signal processing device by connecting a plurality of optical integrated circuit chips to an electric substrate, comprising: a step of electrically connecting one of the plurality of optical integrated circuit chips to the electric substrate; and a step of electrically connecting another optical integrated circuit chip to the electric substrate via the optical integrated circuit chip.

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