WO2019225566A1

WO2019225566A1 - Optical integrated circuit and integrated circuit

Info

Publication number: WO2019225566A1
Application number: PCT/JP2019/019997
Authority: WO
Inventors: 近藤　正彦; 正人森藤; 雄次宮本
Original assignee: 国立大学法人大阪大学
Priority date: 2018-05-24
Filing date: 2019-05-21
Publication date: 2019-11-28
Also published as: JP7019220B2; JPWO2019225566A1

Abstract

An optical integrated circuit (104) according to the present invention is provided with: an optical waveguide (203 or 204); and a laser diode (202) or a photodiode (201), which is formed on a side of the optical waveguide (203 or 204), and which converts an electrical signal into an optical signal and outputs the optical signal to the optical waveguide (204), or alternatively converts an optical signal transmitted through the optical waveguide (203) into an electrical signal. The laser diode (202) or the photodiode (201) comprises: a circular main resonator (401) which is surrounded by a photonic crystal structure; and an auxiliary resonator (402) which is formed in the vicinity of the main resonator (401), while being surrounded by the photonic crystal structure.

Description

Optical integrated circuit and integrated circuit

The present disclosure relates to an optical integrated circuit including an optical diode having a resonator surrounded by a photonic crystal structure.

An optical integrated circuit having a resonator surrounded by a photonic crystal structure is described in Patent Document 1 and Patent Document 2. For example, in the optical integrated circuits described in Patent Document 1 and Patent Document 2, a plurality of resonators are formed on the sides of the optical waveguide, and optical signals generated by the plurality of resonators are output to the optical waveguide.

JP 2007-194301 A JP 2009-239260 A

In such an optical integrated circuit, it is preferable that the optical signal output from the resonator can be transmitted in one direction of the optical waveguide, or the optical signal transmitted from one direction of the optical waveguide can be converted into an electric signal.

Therefore, the present disclosure provides an optical integrated circuit or an integrated circuit capable of increasing a ratio of an optical signal output in one direction of an optical waveguide or a ratio of an optical signal transmitted from one direction input to a resonator. With the goal.

An optical integrated circuit according to an aspect of the present disclosure is formed on the side of the optical waveguide and the optical waveguide, and converts an electrical signal into an optical signal and outputs the optical signal to the optical waveguide, or A photodiode that converts an optical signal transmitted through the optical waveguide into an electrical signal, and the photodiode is formed in a circular main resonator surrounded by a photonic crystal structure and in the vicinity of the main resonator And a sub-resonator surrounded by the photonic crystal structure.

The present disclosure can provide an optical integrated circuit or an integrated circuit capable of increasing the ratio of an optical signal output in one direction of an optical waveguide or the ratio of an optical signal transmitted from one direction input to a resonator.

FIG. 1 is a diagram illustrating a configuration of an integrated circuit according to an embodiment. FIG. 2 is a perspective view of the optical integrated circuit according to the embodiment. FIG. 3 is a diagram illustrating a state of connection between the optical integrated circuit and the optical waveguide according to the embodiment. FIG. 4 is a diagram showing a state of connection between the optical integrated circuit and the optical fiber according to the embodiment. FIG. 5 is a plan view of the laser diode and the optical waveguide according to the embodiment. FIG. 6 is a plan view of the laser diode and the optical waveguide according to the embodiment. FIG. 7 is a diagram illustrating simulation conditions for changing the position of the sub-resonator according to the embodiment. FIG. 8 is a diagram illustrating the left / right ratio with respect to the position of the sub-resonator according to the embodiment. FIG. 9 is a diagram illustrating the width of the sub-resonator according to the embodiment. FIG. 10 is an enlarged view of the periphery of the optical waveguide according to the embodiment. FIG. 11 is a diagram illustrating the coupling efficiency with respect to the shift amount of the holes on the side of the optical waveguide according to the embodiment. FIG. 12 is a plan view of a laser diode and an optical waveguide according to a modification of the embodiment. FIG. 13 is a diagram showing the coupling efficiency with respect to the shift amount of the side holes of the optical waveguide according to the modification of the embodiment.

(Knowledge that became the basis of this disclosure)
The development of information society in recent years is remarkable. This is largely due to software development. On the other hand, the development of hardware has already reached a point where it is close to the physical limit, and there is little room for elongation. For example, the clock speed of the semiconductor CPU chip, which is the core of information processing, has hardly changed in the last 10 years. Information transmission within the chip is performed by metal wiring, and signal delay occurs due to miniaturization of the wiring. When the clock speed is increased, the chip itself generates heat and power consumption increases greatly. Currently, a clock speed of about 3 GHz is a compromise. On the other hand, in order to improve the performance of the CPU chip, a plurality of parts called cores that perform information processing are provided, and parallel processing is performed by the plurality of cores.

The size of the CPU chip is several centimeters, and about 10 billion transistors are formed in it. When these are moved at the same clock speed, problems of heat generation and power consumption occur. As a solution, there is a method of performing information processing with a plurality of cores having a small size.

In order to perform parallel processing with multiple cores, information transmission between cores is important. In the current CPU chip, since information transmission is all performed by metal wiring, there is a problem of heat generation and power consumption in the metal wiring.

In the CPU chip of the present disclosure, optical wiring is used for information transmission between cores. Conventional optical transmission technology is used for relatively long-distance information transmission, and the size of the optical transmission module is large. Therefore, it is difficult to incorporate such a technique in the chip. In the present disclosure, a micro optical module that enables this will be described.

Further, the optical modules described in Patent Document 1 and Patent Document 2 have the following problems. In these optical modules, an optical diode having a resonator on the side of the optical waveguide is formed. The optical signal generated by the photodiode is output to the optical waveguide. Here, the optical signal output to the optical waveguide needs to be transmitted in one direction of the optical waveguide. However, in the prior art, the optical signal is transmitted in both directions. For example, when an optical signal is transmitted in the left direction, the optical signal transmitted in the right direction is reflected by the phase adjustment region at the end of the optical waveguide, and this reflected wave is transmitted in the left direction. Therefore, it is possible to suppress the attenuation of the optical signal by adjusting the phase of the optical signal output in the left direction from the resonator and the phase of the reflected wave to be the same phase. However, when a plurality of resonators having different wavelengths are provided on the side of one optical waveguide, there is a problem that it is difficult to adjust the phases of all the optical signals of the plurality of resonators. This can cause errors in optical transmission.

According to this, by providing the sub-resonator, the ratio of the optical signal output in one direction of the optical waveguide or the ratio of the optical signal transmitted from one direction input to the resonator can be increased.

For example, the sub-resonator may be formed asymmetrically with respect to the clockwise and counterclockwise optical signals in the main resonator.

For example, the sub-resonator may have different effects on the clockwise optical signal and the counterclockwise optical signal in the main resonator.

For example, the sub-resonator may be formed other than between the main resonator and the optical waveguide.

According to this, it is possible to suppress the sub resonator from inhibiting optical coupling between the main resonator and the optical waveguide.

For example, the main resonator and the sub resonator may be adjacent to each other.

According to this, the ratio of the optical signal output in one direction of the optical waveguide or the ratio of the optical signal transmitted from one direction input to the resonator can be further increased.

For example, the sub-resonator may be formed by removing holes having a photonic crystal structure of 1 to 3 inclusive.

For example, the optical waveguide is surrounded on both sides by a photonic crystal structure, and the interval between the photonic crystal structures on both sides of the optical waveguide is a photonic crystal structure other than both sides of the optical waveguide. It may be wider than the interval.

According to this, the coupling efficiency between the main resonator and the optical waveguide can be improved.

For example, the optical integrated circuit includes a plurality of photodiodes including the photodiode, and the plurality of photodiodes are formed on the sides of the optical waveguide. (1) Electric signals have different wavelengths from each other. Converts to an optical signal and outputs the optical signal to the optical waveguide, or (2) converts an optical signal having a different wavelength transmitted through the optical waveguide into an electrical signal, and the optical waveguide has a signal transmission direction. You may have the groove | channel formed along.

According to this, by providing the groove in the optical waveguide, the coupling efficiency between the plurality of photodiodes having different wavelengths and the optical waveguide can be improved.

An integrated circuit according to an aspect of the present disclosure is an integrated circuit that transmits a signal via electricity and light, and includes the optical integrated circuit.

An integrated circuit according to an aspect of the present disclosure includes a plurality of cores and the optical integrated circuit that transmits signals between the plurality of cores.

According to this, high performance of an integrated circuit having a plurality of cores can be realized.

For example, the integrated circuit may include a plurality of blocks each including a plurality of the cores, and the optical integrated circuit may transmit signals between the plurality of blocks.

According to this, by using electrical wiring in the block and using optical wiring between the blocks, an increase in the optical wiring can be suppressed and high performance of the integrated circuit can be realized.

Note that these comprehensive or specific modes may be realized by a system, a method, or an integrated circuit, and may be realized by any combination of the system, the method, and the integrated circuit.

Hereinafter, embodiments will be specifically described with reference to the drawings. Note that each of the embodiments described below shows a specific example of the present disclosure. Numerical values, shapes, materials, components, arrangement positions and connection forms of components, steps, order of steps, and the like shown in the following embodiments are merely examples, and are not intended to limit the present disclosure. In addition, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims indicating the highest concept are described as optional constituent elements.

(Embodiment)
Currently, the number of cores of commercially available CPUs is 10 or less, but there is a demand for an increase of almost one digit in the near future. Specifically, a CPU having 9 × 9 = 81 cores is manufactured. In order to connect all the 81 cores with optical waveguides, nearly 10,000 optical waveguides are required. The optical waveguide has almost no loss, and when it is used within the size of the CPU chip, there is no signal delay, so there is no need to consider the distance between the cores in the design. However, the optical waveguide is larger in size than the electrical wiring. Further, when the optical waveguide is three-dimensionally crossed, its production is not easy and the cost is high. A practical configuration is a hybrid of electrical wiring and optical wiring.

FIG. 1 is a diagram showing a configuration of an integrated circuit 100 according to the present embodiment. FIG. 1 is a schematic diagram, and the ratio of the size of each component does not necessarily match the actual one. The integrated circuit 100 transmits signals via electricity and light. As shown in FIG. 1, the integrated circuit 100 is, for example, a semiconductor chip and functions as a CPU. The integrated circuit 100 includes nine 3 × 3 blocks 101. Each block 101 includes nine 3 × 3 cores 102 (processor cores). That is, the integrated circuit 100 includes 81 9 cores of 9 × 9. The core 102 does not have to be a processor core, and may be an arbitrary processing circuit.

Information transmission between a plurality of cores 102 included in one block 101 is performed by electrical wiring. Optical wiring is used for information transmission between the plurality of blocks 101 and information transmission between the integrated circuit 100 and the outside.

Specifically, each block 101 includes one port 103. The port 103 includes a part of the core 102 and four optical integrated circuits 104 (optical modules). The port 103 transmits a signal between the blocks 101 via the optical waveguide 105 or transmits a signal between the block 101 and the outside via the optical fiber 106. For example, among the nine cores 102 included in one block 101, the central core 102 functions as a communication-dedicated core, and transmits electrical signals between the other eight cores 102 and the port 103. Do. For example, the block 101 is about 1 cm square, and the core 102 is about 3 mm square. The port 103 is about 1 mm square. That is, for example, the size of the port 103 is smaller than the size of the core 102. Note that the size of the port 103 may be larger than the size of the core 102. In addition, a part of the central core 102 may function as the port 103, or a core dedicated to communication may not be provided, and a part of each of the nine cores 102 may function as the port 103.

The optical integrated circuit 104 transmits signals between the plurality of ports 103. Specifically, the optical integrated circuit 104 transmits signals between the plurality of blocks 101.

More specifically, the four optical integrated circuits 104 transmit optical signals to other blocks 101 adjacent to the four sides or to the outside. Specifically, an optical waveguide 105 is used to transmit an optical signal between the blocks 101, and an optical fiber 106 is used to transmit an optical signal between the block 101 and the outside.

Note that the numbers and sizes of the blocks 101 and the cores 102 are examples, and any number or size of the blocks 101 and the cores 102 may be used.

Also, with the configuration shown in FIG. 1, a network can be built in the CPU. As a result, even if any of the optical integrated circuits 104 fails, information can be transmitted via a detour route. Therefore, it is possible to suppress a decrease in CPU performance when the optical integrated circuit 104 fails.

FIG. 2 is a perspective view showing the configuration of the optical integrated circuit 104. An optical integrated circuit 104 shown in FIG. 2 is a semiconductor integrated circuit that mutually converts an optical signal including an optical signal having a plurality of wavelengths and an electrical signal, and includes a plurality of photodiodes (PD) formed on a semiconductor substrate 205. 201a to 201c, a plurality of laser diodes (LD) 202a to 202c, an input optical waveguide 203, and an output optical waveguide 204. Note that the photodiodes 201a to 201c are represented as photodiodes 201 unless otherwise distinguished, and the laser diodes 202a to 202c are represented as laser diodes 202 unless otherwise distinguished.

The input optical waveguide 203 is an optical waveguide that transmits an input optical signal 208 input from the outside. The output optical waveguide 204 is an optical waveguide that transmits an output optical signal 209 output to the outside.

The plurality of photodiodes 201 are formed on the side of the optical waveguide 203 and are optically connected to the optical waveguide 203. The plurality of photodiodes 201 are photodiodes that convert the input optical signal 208 transmitted by the optical waveguide 203 into an electrical signal. Each photodiode 201 includes an electrode 206. Each photodiode 201 converts light of different wavelengths contained in the input optical signal 208 into an electrical signal. For example, the wavelength of the optical signal that the photodiode 201a converts into an electrical signal is 1290 nm, the wavelength of the optical signal that the photodiode 201b converts into an electrical signal is 1300 nm, and the wavelength of the optical signal that the photodiode 201c converts into an electrical signal The wavelength is 1310 nm.

The plurality of laser diodes 202 are formed on the side of the optical waveguide 204 and are optically connected to the optical waveguide 204. The plurality of laser diodes 202 are optical diodes that convert an electrical signal into an output optical signal 209 and output it to the optical waveguide 204. Each laser diode 202 includes an electrode 206. Each laser diode 202 converts an electrical signal into an optical signal having a different wavelength. For example, the wavelength of the optical signal output from the laser diode 202a is 1290 nm, the wavelength of the optical signal output from the laser diode 202b is 1300 nm, and the wavelength of the optical signal output from the laser diode 202c is 1310 nm.

FIG. 3 is a diagram schematically showing a state of connection between the optical integrated circuit 104 and the optical waveguide 105. As shown in FIG. 3, an IC 302, an electrode 303, and a wiring 304 are formed on a substrate 301. The substrate 301 is, for example, a Si substrate.

The IC 302 is an IC that performs amplification and processing of the electrical signal output from the photodiode 201 of the optical integrated circuit 104 and supplies the electrical signal to the laser diode 202 of the optical integrated circuit 104. Here, the optical integrated circuit 104, the IC 302, the electrode 303, and the wiring 304 are included in the port 103 shown in FIG. The IC 302 is a part of the core 102, for example.

2 is turned upside down, and the electrode 303 and each photodiode 201 of the optical integrated circuit 104 and the electrode 206 of each laser diode 202 are flip-chip bonded using solder bumps. In addition, the electrode 303 and the IC 302 are connected through a wiring 304. Thereby, the optical integrated circuit 104 and the IC 302 are connected. Further, the optical waveguide 105 and the

optical waveguides

203 and 204 of the optical integrated circuit 104 are connected.

FIG. 4 is a diagram schematically showing a state of connection between the optical integrated circuit 104 and the optical fiber 106. The connection relationship between the substrate 301 and the optical integrated circuit 104 is the same as in FIG.

The optical fiber 106 is housed in a V-shaped groove formed on the substrate 301. The optical fiber 106 and the

optical waveguides

203 and 204 of the optical integrated circuit 104 are connected.

Since the optical integrated circuit 104 in this embodiment has a simple planar structure, it can be easily integrated as shown in FIGS. In addition, it is possible to fabricate optical wiring between the blocks 101 and outside the chip by using the same optical integrated circuit 104 by the same method. As a result, it is possible to reduce the cost and improve the life of the chip.

FIG. 5 is a top view of the laser diode 202 and the optical waveguide 204 shown in FIG. As shown in FIG. 5, the laser diode 202 includes a main resonator 401, a sub resonator 402, and an electrode 206.

The main resonator 401, the sub resonator 402, and the optical waveguide 204 are formed in the two-dimensional photonic crystal structure. That is, the main resonator 401, the sub resonator 402, and the optical waveguide 204 are surrounded by the two-dimensional photonic crystal structure. The photonic crystal structure has a refractive index periodic structure formed by arranging with a predetermined period. Specifically, a hole is arranged in a semiconductor in a two-dimensional triangular lattice shape. For example, the lattice constant (lattice spacing) a of the photonic crystal structure is 340 nm, and the radius r of the holes is 0.3a. These values are merely examples, and the present invention is not limited to these values. The values described below are all examples and are not limited thereto.

In the region of the two-dimensional photonic crystal structure, light cannot exist, and light can exist only in a portion called a defect whose arrangement is disturbed. Therefore, when a linear defect is produced in the two-dimensional photonic crystal structure, light can enter this portion and function as an optical waveguide. If a defect that resonates light of a specific wavelength is disposed near the optical waveguide, it functions as a resonator. Further, the wavelength of light to be resonated is determined according to the shape and size of the resonator. Thereby, optical signals having different wavelengths can be emitted from the common optical waveguide.

The main resonator 401 has a circular shape and is optically connected to the optical waveguide 204. In addition, about the cross-sectional structure and material of the laser diode 202, the structure similar to patent document 1 or patent document 2 can be used, for example. Further, in this specification, a main resonator 401 is defined as a region including a region where no holes are formed and one round of holes surrounding the region. Similarly, a sub-resonator 402 is defined to include a region in which no holes are formed and one round of holes surrounding the region.

The electrode 206 of the laser diode 202 is formed above the main resonator 401. An optical signal is generated according to the electrical signal applied to the electrode 206 and output to the optical waveguide 204. The shape of the electrode 206 may be a shape that covers the entire main resonator 401 when viewed from above, and need not be the same shape as the main resonator 401. For example, the size of the electrode 206 is larger than the size of the main resonator 401 in order to perform alignment with the electrode 303 connected to the IC 302. For example, the radius R of the main resonator 401 is about 1 μm, and the length of one side of the electrode 206 is about 5 μm to 10 μm.

As described above, the electrode 206 is flip-chip bonded using the electrode 303 and the solder bump. At this time, if bonding using solder bumps is performed on the upper part of the main resonator 401, the characteristics of the main resonator 401 may deteriorate. Therefore, it is preferable that the electrode 206 has a shape and size that can be bonded using a solder bump in a region other than the upper portion of the main resonator 401.

The sub-resonator 402 is smaller than the main resonator 401 and is formed in the vicinity of the main resonator 401. For example, as shown in FIG. 5, an electrode 206 is formed on the sub-resonator 402. Here, the main resonator 401 and the electrode 206 are electrically connected, but the sub-resonator 402 and the electrode 206 are not electrically connected. Specifically, the core layer of the main resonator 401 is electrically connected to the electrode 206 through a conductive cladding layer formed thereabove. On the other hand, a non-conductive cladding layer is formed above the core layer of the sub-resonator 402. As a result, the core layer of the sub-resonator 402 and the electrode 206 are not electrically connected. Note that the electrode 206 may not be formed on the sub-resonator 402.

In addition, although detailed description is abbreviate | omitted about the structure of the photodiode 201, the structure similar to patent document 1 or patent document 2 can be used, for example. Alternatively, the photodiode 201 and the optical waveguide 203 may have the same configuration as that of the main resonator 401 and the optical waveguide 204 of the laser diode 202. That is, it is preferable that the photodiode 201 also includes the sub resonator 402.

In the following, the operation of the main resonator 401 when there is no sub-resonator 402 will be described first. The light generated in the circular main resonator 401 has the property of going straight. Since light cannot enter the photonic crystal structure in which the holes are two-dimensionally arranged, the light goes around the outermost periphery of the main resonator 401. Since the main resonator 401 is surrounded by 18 vacancies, only 9-wave waves exist stably as standing waves. This standing wave is also a superposition of clockwise (counterclockwise) and counterclockwise (counterclockwise) circulating waves. The clockwise circular wave is optically coupled to the optical waveguide 204 in the upper part of the main resonator 401 in FIG. 5 and is emitted to the right of the optical waveguide 204 in FIG. On the other hand, the counterclockwise circular wave is emitted leftward of the optical waveguide 204. Since the clockwise and counterclockwise light paths are exactly the same, the laser gain is also the same, and light of the same intensity is emitted from the left and right in the optical waveguide 204.

Here, the optical signal only needs to be emitted in the left direction of the optical waveguide 204, and does not need to be emitted in the right direction. The optical signal transmitted in the right direction is reflected by the phase adjustment region at the right end of the optical waveguide 204 shown in FIG. 2, and the reflected wave is transmitted in the left direction. Therefore, the attenuation of the optical signal is suppressed by adjusting the position of the phase adjustment region so that the phase of the optical signal output from the resonator to the left and the phase of the reflected wave are the same. it can. As shown in FIG. 2, when a plurality of laser diodes 202 having different wavelengths are provided on the side of one optical waveguide 204, the phases of all the optical signals of the plurality of laser diodes 202 can be adjusted. There is a problem that it is difficult.

In this embodiment, the optical signal emitted in the right direction is reduced by providing the sub-resonator 402. Hereinafter, this principle will be described.

The counterclockwise light travels along the outer periphery of the main resonator 401 at 11 o'clock, 10 o'clock, 9 o'clock, 8 o'clock, 7 o'clock, 6 o'clock, and 5 o'clock, and is not affected by the sub-resonator 402. Laser oscillation is obtained with the same gain as without 402. On the other hand, clockwise light travels around the outer periphery of the main resonator 401 at 1 o'clock, 2 o'clock, 3 o'clock, 4 o'clock, 5 o'clock, and light at a position of 6 o'clock is partly sub-resonant. Enter the vessel 402. The light that has entered the sub-resonator 402 is reflected in the sub-resonator 402 and returns to the main resonator 401 again. Since the reflected light travels counterclockwise, it affects the clockwise circular wave, and the clockwise laser light is significantly weakened.

It should be noted that changing the length of the sub-resonator 402 (the size in the left-right direction in FIG. 5) had almost no effect on the degree to which the clockwise light was reduced. In other words, the reason why the clockwise light is weak is not because the traveling wave and the reflected wave are in opposite phases and cancel each other, but because the reflected wave and the traveling wave are different in phase, the laser oscillation gain is reduced. It is assumed.

In FIG. 5, the sub-resonator 402 is formed by not creating two holes, but even one hole functions as the sub-resonator 402. Further, in order to allow a large amount of clockwise light to enter the sub-resonator 402, the hole at the right end of the sub-resonator 402 is shifted slightly from the original position of the triangular lattice to a position closer to the main resonator 401. Similarly, the width of the sub-resonator 402 (the vertical size in FIG. 5) is slightly narrowed.

In the circular main resonator 401 with the sub-resonator 402 shown in FIG. 5, counterclockwise laser light is mainly generated, so that light traveling mainly to the left is mainly used in the optical waveguide 204. Note that the positional relationship between the main resonator 401 and the optical waveguide 204 is designed as shown in FIG. 5 so that the optical coupling efficiency between the main resonator 401 and the optical waveguide 204 is about 30%.

FIG. 6 is a diagram illustrating an example in which two resonators are arranged on both sides of the optical waveguide 204. As shown in FIG. 6, the main resonator 401 a and the sub resonator 402 a are formed below the optical waveguide 204, and the main resonator 401 b and the sub resonator 402 b are formed above the optical waveguide 204.

In FIG. 6, the sub-resonator 402a is formed by not creating one hole. The sub-resonator 402a is at a position rotated right by 60 degrees with respect to the sub-resonator 402 shown in FIG. Also in this case, as in the case of FIG. 5, the counterclockwise laser beam is mainly used, and the laser beam is emitted from the left side of the optical waveguide 204.

Also, the radius R2 of the main resonator 401b is slightly larger than the radius R1 of the main resonator 401a. Here, the length of the circumference where the standing wave exists is proportional to the radius R. Also, in the main resonator 401b, only the 9-wave standing waves exist stably as in the main resonator 401a. Therefore, the wavelength of the main resonator 401b is slightly longer than the wavelength of the main resonator 401a. Thus, the output wavelengths of the main resonator 401a and the main resonator 401b are different.

The basic design of the main resonator 401a and the sub resonator 402a and the main resonator 401b and the sub resonator 402b is vertically symmetric with respect to the optical waveguide 204 as an axis. That is, in the main resonator 401 b, clockwise laser light is mainly used, and an optical signal is emitted from the left side of the optical waveguide 204.

6 is repeated, a wavelength division multiplexing optical module as shown in FIG. 2 can be manufactured. Here, since the size of the main resonator 401 is extremely small, for example, 2 μm, the size of the optical integrated circuit 104 is very small, about 100 μm square. As a result, the port 103 can be realized with about 1 mm square. Thus, an integrated circuit 100 using an optical wiring can be realized while suppressing an increase in size in a CPU chip of about 3 cm square.

Although the configuration of the laser diode 202 has been mainly described here, the ratio of the optical signal transmitted from one direction input to the resonator is increased by using the same configuration for the photodiode 201. The effect of being able to be realized.

As described above, the optical wiring can be introduced into the CPU chip and used for information transmission between the cores. This improves the CPU performance by one to two digits. The impact of this disclosure is very significant in the information society.

Also, the small size of the optical module (optical integrated circuit 104) directly leads to a reduction in the price of the optical module. The smaller the module size, the more modules can be made from a single wafer, so the unit price of the optical module is reduced. The flip chip bonding shown in FIGS. 3 and 4 can be automated using an infrared camera. Therefore, the optical wiring in the chip can be realized while suppressing the increase in the price of the chip.

In addition, in order to perform optical wavelength division multiplexing communication as in the present embodiment, the wavelength of each photodiode must be within the allowable range of the design value. In general, since the wavelength of the photodiode is affected by the environmental temperature, it is necessary to keep the temperature of the optical module constant (for example, 50 ° C.) using a thermoelectric element or the like. Since the optical module 104 according to the present embodiment is very small, the power consumption of the thermoelectric element is very small and the response to changes in the environmental temperature is excellent. This temperature control mechanism is a part of the function required for the port 103.

Hereinafter, details of the sub-resonator 402 will be described. As described above, the sub-resonator 402 is disposed so as to be optically coupled to one of the clockwise light and the counterclockwise light of the main resonator 401 and not to be optically coupled to the other. In other words, the sub-resonator 402 is arranged so that optical coupling between one of the clockwise light and the counterclockwise light of the main resonator 401 is stronger (or weaker) than the other. That is, the sub resonator 402 is formed asymmetrically with respect to the clockwise and counterclockwise optical signals in the main resonator 401. Further, the sub-resonator 402 has different effects on the clockwise optical signal and the counterclockwise optical signal in the main resonator 401.

Also, the sub-resonator 402 is preferably formed on the opposite side of the main resonator 401 from the optical waveguide 204. For example, in FIG. 5, the center (or upper end) of the sub-resonator 402 is disposed below the line passing through the center of the main resonator 401 and parallel to the optical waveguide 204. That is, the sub resonator 402 is not formed between the main resonator 401 and the optical waveguide 404. In other words, the sub-resonator 402 is formed other than between the main resonator 401 and the optical waveguide 404. Thereby, it is possible to suppress the sub resonator 402 from inhibiting optical coupling between the main resonator 401 and the optical waveguide 204.

Further, the main resonator 401 and the sub resonator 402 may be adjacent to each other. Hereinafter, a simulation result when the distance between the sub resonator 402 and the main resonator 401 is changed will be described. FIG. 7 is a diagram illustrating simulation conditions. FIG. 8 is a diagram showing a simulation result when the defect position x of the sub-resonator 402 is changed as shown in FIG. Note that the length of the defect is one hole. The vertical axis of the graph shown in FIG. 8 indicates the ratio of the energy of the optical signal output in the right direction and the left direction (hereinafter referred to as the left / right ratio). Is high (the energy of the optical signal in an unnecessary direction is low).

As shown in FIG. 8, when the main resonator 401 and the sub resonator 402 are adjacent to each other (x = 1), the left / right ratio becomes the highest. Further, when x = 0, the left / right ratio is reduced. This is presumably because the sub-resonator 402 affects both clockwise and counterclockwise light.

Further, as shown in FIG. 9, when the defect length d (number of holes to be removed) of the sub-resonator 402 is changed, the right / left ratio becomes high when the number of holes to be removed is 1 to 3, In addition, there was no change in the left / right ratio during this period. On the other hand, it was found that when the number of holes to be removed is 4 or more, the left / right ratio is lowered. Therefore, the sub-resonator 402 is preferably formed by removing holes having a photonic crystal structure of 1 to 3 inclusive.

Further, in the present embodiment, the interval between the holes on both sides of the optical waveguide 204 is made wider than the interval a between the other holes. Thereby, the coupling efficiency of optical coupling between the main resonator 401 and the optical waveguide 204 (hereinafter also simply referred to as “coupling efficiency”) can be improved.

FIG. 10 is an enlarged view of the region 403 in FIG. In FIG. 10, broken holes indicate holes arranged at intervals a as in the case of other holes. As shown in FIG. 10, the holes on both sides of the optical waveguide 204 are shifted to the optical waveguide 204 side by −Δs. That is, the gap between the holes on both sides of the optical waveguide 204 is wider than the gap a between the other holes. Note that Δs is positive in the direction away from the optical waveguide 204.

FIG. 11 is a diagram showing a simulation result of the coupling efficiency with respect to Δs / a. As shown in FIG. 11, the coupling efficiency can be improved by appropriately setting Δs.

Further, as shown in FIG. 11, an appropriate value of Δs changes by changing the radius R of the main resonator 401, that is, by changing the wavelength. Thus, when a plurality of laser diodes 202 having different wavelengths are provided for one optical waveguide 204, it is difficult to increase the coupling efficiency for all of the plurality of laser diodes 202.

On the other hand, by forming the groove 501 in the optical waveguide 204, the optimum wavelength dependency of Δs can be reduced. FIG. 12 is a top view of the optical waveguide 204 and the laser diode 202 in this case. As shown in FIG. 12, the optical waveguide 204 has a groove 501 formed along the signal transmission direction. For example, the width of the groove 501 is 0.6a. In addition, the depth of the groove 501 is, for example, about the same as the hole or deeper than the hole.

FIG. 13 is a diagram showing a simulation result of the coupling efficiency with respect to Δs / a in this case. As shown in FIG. 13, by forming the groove 501, the optimum wavelength dependency of Δs can be reduced. Thereby, the optimal Δs can be set for a plurality of laser diodes 202 having different wavelengths.

Note that the method of shifting the holes by Δs and the method of providing the groove 501 can also be applied to the optical waveguide 203 connected to the photodiode 201.

Although the optical integrated circuit and the integrated circuit according to the embodiment of the present invention have been described above, the present disclosure is not limited to this embodiment.

For example, in the above description, the laser diode 202 and the photodiode 201 are both provided with the sub-resonator 402, but only one of them may be provided with the sub-resonator 402. Similarly, the characteristic configuration of the present disclosure described above may be applied to only one of the laser diode 202 and the photodiode 201.

In the above description, the example in which the plurality of laser diodes 202 and the plurality of photodiodes 201 are alternately arranged above and below the

optical waveguide

204 or 203 has been described. However, the plurality of laser diodes 202 and the plurality of photodiodes 201 are arranged. This arrangement is not limited to this. For example, the plurality of laser diodes 202 and the plurality of photodiodes 201 may be arranged in the same direction of the

optical waveguide

204 or 203.

Further, all the numbers used above are examples for specifically explaining the present disclosure, and the present disclosure is not limited to the illustrated numbers.

As described above, the optical integrated circuit and the integrated circuit according to one or more aspects have been described based on the embodiment, but the present disclosure is not limited to this embodiment. Unless it deviates from the gist of the present disclosure, various modifications conceived by those skilled in the art have been made in this embodiment, and forms constructed by combining components in different embodiments are also within the scope of one or more aspects. May be included.

The present disclosure can be applied to an optical integrated circuit and an optical module, and in particular to an optical integrated circuit and an optical module for wavelength division multiplexing transmission in optical communication.

DESCRIPTION OF SYMBOLS 100 Integrated circuit 101 Block 102 Core 103 Port 104 Optical

integrated circuit

105, 203, 204 Optical waveguide 106

Optical fiber

201, 201a, 201b, 201c

Photodiode

202, 202a, 202b, 202c Laser diode 205

Semiconductor substrate

206, 303 Electrode 208 Input light Signal 209 Output optical signal 301 Substrate 302 IC
304

Wiring

401, 401a, 401b

Main resonator

402, 402a, 402b Sub resonator 403 Region 501 Groove

Claims

An optical waveguide;
Light that is formed on the side of the optical waveguide and converts an electrical signal into an optical signal and outputs the optical signal to the optical waveguide, or converts an optical signal transmitted through the optical waveguide into an electrical signal A diode and
The photodiode is
A circular main resonator surrounded by a photonic crystal structure;
An optical integrated circuit having a sub-resonator formed in the vicinity of the main resonator and surrounded by a photonic crystal structure.
The optical integrated circuit according to claim 1, wherein the sub-resonator is formed asymmetrically with respect to the clockwise and counterclockwise optical signals in the main resonator.
The optical integrated circuit according to claim 1, wherein the sub-resonator has different influences on a clockwise optical signal and a counterclockwise optical signal in the main resonator.
The optical integrated circuit according to any one of claims 1 to 3, wherein the sub-resonator is formed in a portion other than between the main resonator and the optical waveguide.
The optical integrated circuit according to any one of claims 1 to 4, wherein the main resonator and the sub resonator are adjacent to each other.
6. The optical integrated circuit according to claim 1, wherein the sub-resonator is formed by removing holes having a photonic crystal structure of 1 to 3 inclusive.
The optical waveguide is surrounded on both sides by a photonic crystal structure,
The optical integrated circuit according to any one of claims 1 to 6, wherein an interval between the photonic crystal structures on both sides of the optical waveguide is wider than an interval between the photonic crystal structures on both sides of the optical waveguide.
The optical integrated circuit includes a plurality of photodiodes including the photodiode.
The plurality of photodiodes are formed on the side of the optical waveguide, and (1) convert electrical signals into optical signals having different wavelengths and output the optical signals to the optical waveguide, or ( 2) Converting optical signals having different wavelengths transmitted through the optical waveguide into electrical signals;
The optical integrated circuit according to claim 1, wherein the optical waveguide has a groove formed along a signal transmission direction.
An integrated circuit that transmits signals via electricity and light,
An integrated circuit comprising the optical integrated circuit according to any one of claims 1 to 8.
With multiple cores,
9. An integrated circuit comprising: the optical integrated circuit according to claim 1 that transmits a signal between the plurality of cores.
The integrated circuit includes a plurality of blocks each including a plurality of the cores;
The integrated circuit according to claim 10, wherein the optical integrated circuit transmits a signal between the plurality of blocks.