JP7454852B2 - Optical devices using nanocarbon materials - Google Patents

Description

The present invention relates to an optical device using a nanocarbon material such as graphene, and particularly to an optical device combining a nanocarbon material and silicon photonics technology.

Light emitting elements, light sources, and photocouplers using nanocarbon materials such as graphene and carbon nanotubes (CNTs) have been proposed (see, for example, Patent Document 1 and Patent Document 2). Nanocarbon materials can be electrically heated at high speed, and a continuous spectrum (white light) can be obtained over a wide wavelength range using blackbody radiation.

On the other hand, silicon photonics technology, which integrates optical circuits using microscopic silicon waveguides on a substrate, is attracting attention. Silicon photonics technology is used in a variety of fields, and many small optical modules and the like for use in WDM (Wavelength Division Multiplexing) optical communication networks have been developed.

An optical phased array is known in which heating efficiency is increased by directly arranging graphene nanoheaters in a silicon waveguide (for example, see Non-Patent Document 1).

Patent No. 5747334 Patent No. 6155012

Yubing Wang, et al., "Improved performance of optical phased arrays assisted by transparent grapheme nanoheaters and air trenches," RSC Adv. 2018, 8, 8442-8449, 23 February 2018

In optical switches and optical path converting elements in optical integrated devices, switching is generally performed using a thermo-optic effect using metal or semiconductor heaters. When a metal or semiconductor heater is used, the switching speed due to temperature changes in the heater is very slow, on the order of kilohertz (kHz), and the structure is complicated. When a heater is brought close to an optical waveguide in order to improve the performance of the device, the loss of the waveguide increases due to light absorption by the heater. Therefore, there is a certain distance between the waveguide and the heater, which causes problems such as low switching efficiency and high power consumption.

An object of the present invention is to provide an optical device that can operate at high speed with low power consumption.

Embodiments provide optical devices using nanocarbon materials such as graphene and carbon nanotubes. In a first aspect of the invention, the optical device comprises:
a first optical waveguide connected to the input optical port;
a second optical waveguide connected to the first output optical port;
a third optical waveguide connected to the second output optical port;
an optical component that optically connects the first optical waveguide to at least one of the second optical waveguide and the third optical waveguide;
a nanocarbon material disposed at least in an area where the optical component is provided;
an electrode pair that applies an electric signal to the nanocarbon material;
The optical path is switched between the first output light port and the second output light port by applying the electric signal.

In a second aspect of the invention, the optical device comprises:
an optical coupler that branches incident light into multiple channels;
a plurality of phase modulators respectively provided in the plurality of channels;
a plurality of output optical ports coupled to outputs of the plurality of phase modulators;
has
The plurality of phase modulators have a covering region covered with a nanocarbon material, and the phase of light passing through the plurality of phase modulators is changed by an electric signal applied to the nanocarbon material from the outside,
The direction of the output light emitted from the plurality of output light ports is determined by the phase difference provided by the plurality of phase modulators.

In a third aspect of the invention, the optical device comprises:
An optical coupler that splits incident light into multiple channels, multiple phase modulators provided in each of the multiple channels, and a nanometer that changes the phase of the light passing through each channel by electrical heating using an external electrical signal. an array phase modulator having a carbon material;
a plurality of array waveguides connected to the output of the array phase modulator;
a condensing waveguide connected to the plurality of array waveguides and condensing output light from the plurality of array waveguides at a predetermined position;
an output light port connected to the output of the light collecting waveguide;
has
The amount of phase change of the plurality of phase modulators is controlled by the electrical signal, and the light focusing position at the output end of the light collecting waveguide is determined.

In a fourth aspect of the invention, the optical device comprises:
a nanostructure having a periodic refractive index distribution;
a nanocarbon material covering the nanostructure;
an electrode for inputting an electric signal applied to the nanocarbon material;
The refractive index of the nanostructure or the interaction with the propagating light is modulated by the electrical heating of the nanocarbon material, and the exit direction of the light incident on the nanostructure changes.

Optical devices capable of high-speed operation with low power consumption will be realized. In particular, high-speed optical path switching and optical sweeping can be realized.

FIG. 2 is a schematic top view of an optical path converter which is an example of the optical device of the first embodiment. FIG. 1B is a perspective view of the optical path changer of FIG. 1A. This is a microscopic image of the manufactured optical path converter before electrode formation. This is a microscopic image of the fabricated optical path converter after electrode formation. This is a microscopic image of the waveguide structure of the manufactured optical path converter. It is a figure which shows the wavelength dependence of the transmitted light and branched light of the optical path changer of embodiment. It is a figure which shows the transmitted light emission state of an optical path changer. It is a figure which shows the branch light emission state of an optical path changer. It is an image showing an experiment of the optical path switching operation of the manufactured optical path converter. This is an image showing branched light emission due to voltage off. This is an image showing transmitted light emission when the voltage is turned on. FIG. 3 is a diagram of the transmitted light spectrum depending on the voltage applied to graphene. FIG. 3 is a diagram showing changes in refractive index with respect to voltage applied to graphene. FIG. 3 is a diagram showing changes in refractive index with respect to power applied to graphene. FIG. 3 is a diagram showing a temporal change in transmitted light intensity when a 100 kHz modulation voltage signal is applied to graphene. FIG. 3 is a diagram showing time-resolved measurement results of thermal radiation when a 1 GHz modulation signal is applied to graphene. FIG. 2 is a diagram showing an example of the configuration of an optical resonator that can be used in the optical device of the embodiment. FIG. 2 is a diagram showing an example of the configuration of an optical resonator that can be used in the optical device of the embodiment. FIG. 2 is a diagram showing an example of the configuration of an optical resonator that can be used in the optical device of the embodiment. FIG. 2 is a diagram showing an example of the configuration of an optical path converter using a Mach-Zehnder interferometer. FIG. 2 is a diagram illustrating a configuration example of an optical path changer using a directional coupler. FIG. 2 is a diagram showing an example of the configuration of an optical path converter using a multimode coupler. FIG. 3 is a diagram showing an example of the arrangement of an optical waveguide and a nanocarbon material. FIG. 3 is a diagram showing an example of the arrangement of an optical waveguide and a nanocarbon material. FIG. 3 is a diagram showing an example of the arrangement of an optical waveguide and a nanocarbon material. FIG. 3 is a diagram showing an example of the arrangement of an optical waveguide and a nanocarbon material. FIG. 3 is a diagram showing an example of the arrangement of an optical waveguide and a nanocarbon material. FIG. 2 is a schematic diagram showing a configuration example of a phase modulator, which is an example of an optical device according to a second embodiment. FIG. 7 is a diagram illustrating a configuration example of a phase modulator, which is an example of an optical device according to a second embodiment. FIG. 7 is a diagram illustrating a configuration example of a phase modulator, which is an example of an optical device according to a second embodiment. FIG. 7 is a diagram illustrating a configuration example of a phase modulator, which is an example of an optical device according to a second embodiment. FIG. 7 is a diagram illustrating a configuration example of a phase modulator, which is an example of an optical device according to a second embodiment. FIG. 7 is a schematic diagram of an optical sweeping device that is an example of an optical device according to a third embodiment. FIG. 2 is a diagram illustrating a configuration example of a phase modulator array used in an optical sweeping device. FIG. 3 is a diagram showing another example of an optical sweeping device. FIG. 7 is a schematic diagram of an optical path control (routing) device that is an optical device of a fourth embodiment. It is a schematic diagram of the spectroscope which is an optical device of 5th Embodiment. FIG. 1 is a schematic diagram of a light detection and distance measuring device to which the light sweeping device of the embodiment is applied. It is a figure which shows the structural example of an optical antenna as another modification. It is a figure which shows the structural example of an optical antenna as another modification.

Embodiments provide optical devices using nanocarbon materials such as graphene and carbon nanotubes. Optical devices are integrated optical devices made by finely processing light-transmitting materials such as silicon, silicon oxide, and silicon nitride, and include optical path changers, optical sweeping devices, spectrometers, phase modulators, optical antennas, and the like.

By providing a heat source using electrical heating in an optical waveguide or resonator that is microfabricated from a light-transmitting material, it is possible to control the refractive index using the thermo-optic effect and control high-speed optical path switching and optical sweeping. .

A nanocarbon material is an atomic-order carbon material in which carbon atoms are arranged on a plane in a six-membered ring structure. Nanocarbon has excellent thermal properties, and has a thermal conductivity that is about 10 times higher than that of copper, which is said to have high thermal conductivity. In addition, since devices with minute structures on the atomic order can be fabricated, the heat capacity, which is a physical quantity proportional to volume, is extremely small. When nanocarbon materials are applied to optical devices, not only can large temperature changes be achieved with very little thermal energy, but the relaxation time of temperature changes can be reduced in proportion to the heat capacity, resulting in optical devices that operate at high speed. can be developed.

Nanocarbon materials can increase heat conduction by utilizing plasmons within nanocarbons and surface polar phonons of the substrate, and can achieve greater heat conduction than semiconductors or metal materials. This characteristic is used to perform high-speed and highly efficient temperature modulation.

When optical path conversion, optical path control (routing), optical sweeping, etc. are performed using nanocarbon materials, high-speed modulation of several hundred kHz or more is possible, and modulation at a maximum speed on the order of gigahertz (GHz) is possible. Compared to optical devices that use conventional metal or semiconductor heaters, it is possible to create optical devices that can operate 100 to 1,000,000 times faster.

<First embodiment>
FIG. 1A shows a top view of an optical path changer 10A of the first embodiment as an example of an optical device, and FIG. 1B shows a perspective view. The optical path changer 10A includes a pair of optical waveguides 11 and 12 formed of a light-transmitting material such as silicon (Si) on a substrate 103, and an optical resonator 13 disposed close to the optical waveguides 11 and 12. It has a nanocarbon material 15 covering the optical waveguides 11 and 12 and the optical resonator 13. Nanocarbon material 15 is connected to a pair of electrodes 14 and 16.

The substrate 103 is, for example, a silicon substrate, an SOI (Silicon on Insulator) substrate, or the like. In this example, optical waveguides 11 and 12 and an optical resonator 13 are formed on a substrate 103 in which a SiO ₂ layer 102 is formed on a Si substrate 101 . When using an SOI substrate, the optical waveguides 11 and 12 and the optical resonator 13 can be formed by using a silicon oxide (SiO ₂ ) layer as an insulating layer as a lower cladding layer and processing the Si layer. In the example of FIG. 1, the optical resonator 13 is a ring resonator.

When light enters the optical waveguide 11 of the optical path converter 10A from the input optical port Pin, the light that goes straight without passing through the optical resonator 13 is output from the transmitted light output port Pout1. The light coupled to the optical resonator 13, circulated, and then coupled to the optical waveguide 12 is emitted from the branched light output port Pout2. Of the optical waveguide 11, the portion from the input optical port Pin to the portion close to the optical resonator 13 is referred to as a first waveguide, and the portion from the portion adjacent to the optical resonator 13 to the transmitted light output port Pout1 is referred to as a second waveguide. good. The portion of the optical waveguide 12 from the portion close to the optical resonator 13 to the branched light output port Pout2 may be used as a second optical waveguide. The optical resonator 13 is an example of an optical component that optically connects the incident light from the incident optical port Pin to the transmitted light output port Pout1 or the branched light output port Pout2.

In normal operation, when monochromatic light such as a laser beam having a specific wavelength is input, by selecting the wavelength, the light is output only from either the transmitted light output port Pout1 or the branched light output port Pout2. Is possible. In other words, the exit of the emitted light can be selected by changing the wavelength of the laser light.

In this state, when voltage or current is applied to the nanocarbon material 15 via the electrodes 14 and 16, the nanocarbon material 15 is heated by the current supply. When the temperature of the nanocarbon material 15 rises, the temperature of the lower optical waveguides 11 and 12 and the optical resonator 13 also rises due to thermal conduction. Due to this temperature rise, the effective refractive index of the optical waveguides 11, 12 and the optical resonator 13 changes, and the substantial optical path length of the optical waveguides 11, 12 and the optical resonator 13 changes.

Depending on whether or not the nanocarbon material 15 is energized, the phase of light propagating through the optical waveguides 11 and 12 and the optical resonator 13 can be changed. Utilizing this phase change, it becomes possible to select the output destination of the light incident from the input optical port Pin between the transmitted light output port Pout1 and the branched light output port Pout2, depending on the presence or absence of energization. The two optical paths can be switched by an external electrical signal.

When the nanocarbon material 15 is not energized, which of the transmitted light output port Pout1 and the branched light output port Pout2 is to be emitted first can be set by determining the wavelength. When no voltage is applied to the nanocarbon material 15, the temperature of the nanocarbon material 15 does not rise, and light is emitted only from the initially set output port, for example, the transmitted light output port Pout1.

When a voltage is applied to the nanocarbon material 15, the temperature of the nanocarbon material 15 increases due to electrical heating. Due to heat conduction, the temperature of the lower optical waveguides 11, 12 and optical resonator 13 also rises, and the refractive index of the optical waveguides 11, 12 and optical resonator 13 changes due to the thermo-optic effect. Due to the change in the refractive index, the phase of the propagating light shifts and interference occurs, and the output port is switched to the branched light output port Pout2. The path of light can be changed by an electric signal applied to the nanocarbon material 15, and it operates as an optical path changer 10A.

2A to 2C are microscopic images of the optical path changer 10A that was actually produced. 2A is an optical microscope image before electrode formation, FIG. 2B is an optical microscope image after electrode formation, and FIG. 2C is an electron microscope image of the waveguide structure near the optical resonator 13. Here, two optical waveguides 11 and 12 are arranged adjacent to a racetrack type optical resonator 13. Graphene, which is a nanocarbon material 15, is formed on an optical circuit made of Si thin wires including an optical resonator 13 and optical waveguides 11 and 12, and electrodes are arranged at both ends of the graphene.

By combining the nanocarbon material 15 and the Si thin wire optical circuit, it is possible to realize an optical path changer 10A with a size of 10 μm×10 μm and operating at high speed.

FIG. 3A is a simulation result of a change in light transmittance when the wavelength of light incident from the input optical port Pin is changed in the manufactured optical path changer 10A. In the figure, the profile described as "transmitted light" is the wavelength dependence of the transmittance at the transmitted light output port Pout1, and the profile described as "branched light" is the transmittance at the branched light output port Pout2. shows the wavelength dependence of The intensity of the transmitted light and the intensity of the branched light change periodically depending on the wavelength of the incident light. When the transmitted light intensity is high, the branched light intensity is low, and when the branched light intensity is strong, the transmitted light intensity is weak. From this figure, it can be seen that the interference state between the light passing through the optical waveguides 11 and 12 and the light passing through the optical resonator 13 changes periodically depending on the wavelength. It is shown that the optical path changer 10A can be controlled by changing the interference state of light. FIG. 3B shows the transmitted light output state of FIG. 3A, and FIG. 3C shows the branched light output state. In the transmitted light output state, the input light travels straight through the waveguide toward the transmitted light output port Pout1. In the branched light output state, the incident light is coupled to the ring resonator, and is coupled from the ring resonator to the other waveguide to head toward the branched light output port Pout2.

FIG. 4A is a diagram illustrating an experiment in which an optical path changing operation is actually performed on the manufactured optical path changing device 10A, and is an optical microscope image (including a partially enlarged image) after electrode formation of the optical path changing device 10A. . The voltage application to graphene, which is the nanocarbon material 15, is switched to switch the output port between Pout1 and Pout2. FIG. 4B is an infrared camera image when no voltage is applied (V=0V), and FIG. 4C is an infrared camera image when voltage is applied (V=3.5V).

The light incident from the input optical port Pin is divided into light that travels straight through the transmission optical waveguide and branched light that passes through the ring resonator and is coupled to the branched optical waveguide. In this configuration example, a wavelength is selected that allows only branched light to be obtained when no voltage is applied to graphene (V = 0V), and Figure 4B shows how the light propagates toward the branched light output port. be observed. In FIG. 4C, it is observed that a voltage is applied to graphene (V=3.5V), the optical path is switched from the branched light side to the transmitted light side, and the light is propagated to the transmitted light output port. It has been demonstrated that by using a graphene heater, an optical path changer 10A that operates at high speed can be realized.

FIG. 5 shows the voltage dependence of the transmittance spectrum in the optical path changer 10A of the embodiment. By changing the voltage applied to graphene, which is the nanocarbon material 15, to 0V, 1V, 2V, and 3V, the peak of the transmittance spectrum shifts to the longer wavelength side. The effective refractive index of the Si waveguide changes and the effective optical path length changes due to the thermo-optic effect caused by heating the graphene with electricity, and the interference conditions for light passing through the optical waveguides 11 and 12 and the optical resonator 13 change. Change. This change in interference conditions causes the transmittance spectrum to change, and the optical path of the transmitted light and the branched light to be switched.

FIG. 6A shows the change in the refractive index of the Si waveguide with the applied voltage to graphene, and FIG. 6B shows the change in the refractive index of the Si waveguide with the power. The refractive index of the Si waveguide can be determined from the transmittance spectrum shown in FIG. Power is determined by measuring the current when voltage is applied. In the samples used in FIGS. 6A and 6B, the refractive index changes almost linearly with respect to the electric power. How the refractive index of an optical waveguide changes depends on the material used for the optical device and the device structure, so the dependence of the refractive index on external electrical input can be designed to suit the application.

FIG. 7 shows the measurement results of the transmitted light intensity at the transmitted light output port Pout1 when a 100 kHz modulation signal was applied to the electrodes 14 and 16 of the optical path changer 10A manufactured in FIG. 2. Graphene is used as the nanocarbon material, and the modulation signal is a square wave signal varying between 0V and 3.5V. Changes in the intensity of transmitted light were measured using an oscilloscope. High-speed optical path selection or optical path switching has been observed in real time.

FIG. 8 shows the results of time-resolved thermal radiation measurements when a 1 GHz modulation signal is input to graphene. The nanocarbon material 15 has a minute structure on the atomic order, has a small heat capacity, and can rapidly modulate temperature. In addition, the nanocarbon material 15 has a thermal conductivity that is approximately 10 times higher than that of copper, which is said to have high thermal conductivity, and furthermore, utilizes plasmons in the nanocarbon and surface polar phonons of the substrate. Even higher thermal conductivity can be obtained. By using the nanocarbon material 15, a large temperature change can be obtained with small thermal energy. Furthermore, the relaxation time for temperature changes is short, and even when a high-speed voltage signal of 1 GHz is input, the temperature of graphene changes following the speed of the modulation signal.

The measurement results in FIG. 8 show that the optical path converter 10A of the embodiment can operate at a maximum speed of 1 GHz. The optical path converter 10A can operate at a speed 100 to 1,000,000 times faster than when a metal or semiconductor heater is used.

The measurement results shown in FIGS. 7 and 8 also apply to the case where carbon nanotubes (CNTs) are used as the nanocarbon material 15. As the CNTs, either single-walled CNTs or multi-walled CNTs may be used. CNTs include semiconductor nanotubes and metal nanotubes, depending on their structure (chirality), and both can be used. CNTs can be formed by various methods such as chemical vapor deposition (CVD) and high pressure carbon monoxide (HiPCO).

When disposing CNTs on the optical waveguides 11 and 12 and the optical resonator 13, a CNT solution may be spin-coated or dip-coated, or transferred with tape, gel, or polymer. Alternatively, CNTs may be grown directly in the region including the optical waveguides 11 and 12 and the optical resonator 13 by CVD. A single CNT carbon nanotube may be used, but since a larger change in refractive index can be obtained by using a large number of CNTs, it is effective to use a CNT thin film made of a network of CNTs. When graphene is used as the nanocarbon material 15, the number of graphene layers is arbitrary, and may be a single layer, two layers, several layers, or multiple layers. Regardless of the method of growing graphene, any method such as CVD, mechanical peeling, transfer, or direct growth can be used.

Nanocarbon material 15 can be electrically heated despite its atomic-order thinness. If a thin film of atomic order is formed using a normal metal material and then electrically heated, the metal will break due to heating or migration, making it impossible to operate the optical device. Nanocarbon material 15 has covalent bonds and is resistant to electrically heated, so it is less likely to break due to electrically heated despite its atomic-order structure, and is highly durable. By combining silicon photonics technology with nanocarbon materials, it is possible to form optical path changers with fine structures at high density.

The nanocarbon material 15 has a unique electronic state due to its minute structure, and this electronic state is advantageous for optical devices. For example, in the case of graphene, in addition to linear energy dispersion of electrons, light absorption can be controlled by the electric field and doping state. Since optical absorption can be suppressed by selecting the electric field and doping state, unlike ordinary metals, even if the nanocarbon material 15 is placed directly above the optical waveguides 11 and 12 or the optical resonator 13, there is no optical loss due to absorption. can be kept low. CNTs have the same effect as graphene, and in addition to being able to control light absorption using an electric field or doping, it is also possible to further suppress light absorption by using semiconductor CNTs.

In the first embodiment, a Si waveguide is formed as a light transmitting material, but if optical confinement by refractive index contrast is possible, silicon oxide, silicon nitride, III-V group or II-VI light transmitting material can be used. A group of semiconductor materials may also be used. Regardless of the type of light-transmitting material, optical path switching can be controlled by applying voltage to the nanocarbon material 15.

9A to 9C show configuration examples of the optical resonator 13. 9A shows a racetrack type ring resonator 131, FIG. 9B shows a circular ring resonator 132, and FIG. 9C shows a disk type resonator 133. Although a racetrack-type ring resonator is used in FIG. 2C, any shape may be used as long as it functions as the optical resonator 13, such as the circular ring resonator 132 shown in FIG. 9B or the disk-type resonator 133 shown in FIG. 9C. etc. may also be used.

FIG. 10A shows an optical path changer 10B as a modification of the optical device of the first embodiment. The optical path changer 10B switches the optical path using a Mach-Zehnder interferometer (MZ). The Mach-Zehnder interferometer (MZ) has a pair of optical waveguides 11 and 12 extending between an optical coupler 17 and an optical coupler 19. Nanocarbon material 15A is placed on optical waveguide 11, and voltage (or current) is applied to nanocarbon material 15A through electrodes 141 and 161. A nanocarbon material 15B is placed on the optical waveguide 12, and a voltage (or current) is applied to the nanocarbon material 15B by the electrodes 142 and 162. A first optical waveguide extends from the input optical port Pin to the optical coupler 17, a second optical waveguide extends from the optical coupler 19 to the output optical port PoutA, and a third optical waveguide extends from the optical coupler 19 to the output optical port PoutB. You can also use it as The Mach-Zehnder interferometer MZ is an optical component that optically connects the incident light from the incident light port Pin to the transmitted light output port Pout1 or the branched light output port Pout2.

The optical waveguides 11 and 12 are heated by applying voltage to the nanocarbon materials 15A and 15B. The nanocarbon material 15A and the nanocarbon material 15B are controlled independently from each other, and either one of the nanocarbon materials 15A and 15B may be heated with electricity, or both may be heated with electricity.

When a voltage is applied, the phase of the light changes in the two optical waveguides 11 and 12 of the Mach-Zehnder interferometer MZ due to the refractive index change due to the thermo-optic effect, and the output light port PoutA and the output light port PoutB are switched. . The optical coupler 17 and the optical coupler 19 each have two waveguides that come close to each other and are coupled by evanescent (near field), but no matter what type of optical coupler is used, For example, a multi-mode interference system (MMI) may be used.

FIG. 10B shows an optical path changer 10C using a directional coupler 170 as a modification of the optical device of the first embodiment. The directional coupler 170 has a structure in which two optical waveguides 171 and 172 are adjacent to each other at a predetermined location. Nanocarbon material 15 is placed over the adjacent portion. The light incident from the input optical port Pin causes mutual interference in the evanescent field in adjacent parts, and the light is distributed to two waveguides 171 and 172 on the output side connected to the output optical ports Pout11 and Pout12, respectively. The distribution ratio is adjusted by applying electrical heating to the nanocarbon material 15 covering the adjacent portion. Since the interference state changes when the nanocarbon material 15 is heated by electricity, and the intensity of the two emitted lights changes, the outputs from the emission light ports Pout11 and Pout12 are switched by applying electricity to the nanocarbon material 15. I can do it. The formed nanocarbon material 15 may have a structure that is symmetrical with respect to the optical axis (propagation axis), or may have a temperature gradient with a structure that is asymmetrical with respect to the optical axis by making the shape of graphene into a trapezoid or the like. .

FIG. 10C shows an optical path changer 10C using a multimode coupler 180 as another modification of the optical device of the first embodiment. This multimode coupler 180 is a one-input, two-output multimode coupler. A Y splitter may be used instead of the multimode coupler 180. The multimode coupler 180 has a structure in which one input waveguide 181 and two output waveguides 182 and 183 are connected to a slab portion 184. The slab section 184 is a coupling section that couples the light propagated through the input waveguide 181 to the output waveguide 182 or 183. In the slab section 184 having a constant width, the incident light is converted into a plurality of propagation modes and coupled to the output waveguide 182 or 183. When using a Y splitter, waveguides 181, 182, and 183 are directly coupled.

The light incident from the input optical port Pin is distributed by optical interference in the slab section 184 and output from the output optical port Pout11 and the output optical port Pout12.The ratio of the light intensity changes depending on the interference state of the slab section 184. be able to. By arranging the nanocarbon material 15 in the slab portion 184 and heating it with electricity, the interference state changes and the light intensity of the two output light ports Pout11 and Pout12 can be switched. The nanocarbon material 15 to be formed may have a symmetrical structure with respect to the optical axis, but as shown in FIG. Also good.

<Example of arrangement of nanocarbon material>
11A to 11E show examples of arrangement of the nanocarbon material 15 in an optical waveguide or optical resonator (hereinafter abbreviated as "optical waveguide 111"). In FIG. 11A, an optical waveguide 111 is formed on the main surface of a substrate 110, and nanocarbon material 15 is disposed to cover the top and side surfaces of the optical waveguide 111. In FIG. 11B, the optical waveguide 111 is a buried waveguide embedded in the substrate 110, and the nanocarbon material 15 directly covers the top surface of the optical waveguide 111. In the case of the buried optical waveguide 111, the substrate surface is flat, and the nanocarbon material 15 can be easily arranged. In both FIGS. 11A and 11B, at least a portion of the optical waveguide 111 may be in contact with the nanocarbon material 15.

As shown in FIGS. 11A and 11B, when the optical waveguide 111 is covered with the nanocarbon material 15, the influence of the temperature rise of the nanocarbon material 15 is directly controlled via evanescent light generated around the optical waveguide 111. It can be used for. When the nanocarbon material 15 is in contact with the optical waveguide 111, the heat of the nanocarbon material 15 is directly transmitted to the optical waveguide 111, so that the temperature of the optical waveguide 111 can be raised with high efficiency. The configurations in FIGS. 11A and 11B realize highly efficient optical path switching control with low power consumption.

In FIG. 11C, a cap layer 112 is disposed between the optical waveguide 111 and the nanocarbon material 15. In FIG. In FIG. 11D, a lower cap layer 113 is disposed between the optical waveguide 111 and the nanocarbon material 15, and an upper cap layer 115 is disposed on the nanocarbon material 15. In FIG. Top cap layer 115 may also be referred to as a protective layer.

When inserting the cap layer 112 or the lower cap layer 113 between the optical waveguide 111 and the nanocarbon material 15 as shown in FIGS. 11C and 11D, these cap layers are formed of a material with a lower refractive index than the optical waveguide 111. It may be made to function as a cladding layer of the optical waveguide 111. By providing the cap layer 112 or the lower cap layer 113, the influence of scattering and light absorption caused by disposing the nanocarbon material 15 on the optical waveguide 111 can be minimized, and the optical path converter 100A (or 100B) can be Loss can be reduced.

The thickness of the cap layer 112 or the lower cap layer 113 can be designed to be an optimal thickness, taking into consideration the heating efficiency of the nanocarbon material 15 and the optical waveguide 111 and the loss due to the nanocarbon material 15. Since the heat conduction from the nanocarbon material 15 to the optical waveguide 111 changes depending on the material of the cap layer 112 or the lower cap layer 113, the optical path conversion performance can be changed by selecting the material of the cap layer 112 or the lower cap layer 113. You can also do that.

When the upper cap layer 115 is disposed on the nanocarbon material 15 as shown in FIG. 11D, when the nanocarbon material 15 is heated with electricity, the nanocarbon material 15 may react with an atmosphere such as oxygen and be damaged. can be prevented.

The cap layer 112, the lower cap layer 113, and the upper cap layer 115 are preferably made of a material with low electrical conductivity. When the optical waveguide 111 is formed of silicon, an inorganic material such as silicon oxide or aluminum oxide, a polymer material such as PMMA (polymethyl methacrylate), or the like can be used as the cap layer. In the structure of FIG. 11D, the lower cap layer 113 may be formed of aluminum oxide and the upper cap layer 115 may be formed of PMMA.

In all of FIGS. 11A to 11D, a thin film 116 of a polar substance (polar crystal) such as oxide or nitride is formed at the contact portion of the nanocarbon material 15, the optical waveguide 111, the substrate 110, and the cap layer 115. You may. In this case, heat escapes quickly due to the surface polar phonons of the polar substance (see arrow h in the figure), enabling rapid temperature changes and improving switching speed. As the polar substance, it is possible to select a substance such as silicon oxide, silicon nitride, boron nitride, alumina, hafnium oxide, etc., in which the atoms constituting the substance are polar to each other and can induce polar phonons. Since polar phonons generated on the surface are used, the polar substance formed can be extremely thin, and it can function satisfactorily even if it is formed on the order of nanometers.

<Second embodiment>
12A to 12E respectively show phase modulators 20A to 20E using nanocarbon as optical devices of the second embodiment. The phase modulator 20A in FIG. 12A applies voltage or current to the optical waveguide 21 formed on the substrate 103 (see FIG. 1), the nanocarbon material 25 disposed on the optical waveguide 21, and the nanocarbon material 25. It has electrodes 24 and 26 for. The operating principle of the phase modulator 20A is the same as that described in the first embodiment, which utilizes the change in the refractive index of the optical waveguide 21 by heating the nanocarbon material 25 with electricity. A change in the refractive index of the optical waveguide 21 changes the propagation speed of light and changes the phase.

Phase modulator 20B in FIG. 12B has one ring resonator 23 arranged adjacent to optical waveguide 21 in addition to the configuration in FIG. 12A. Nanocarbon material 25 covers ring resonator 23 and optical waveguide 21 . A part of the light propagating through the optical waveguide 21 is coupled to the ring resonator 23 and circulates around the ring resonator 23 . When the refractive index of the optical waveguide 21 and the ring resonator 23 changes by heating the nanocarbon material 25 with electricity, the state of interference between the light passing through the ring resonator 23 and the light passing through the optical waveguide 21 changes, and the phase of the transmitted light changes. changes.

The phase modulator 20C in FIG. 12C has a plurality of ring resonators 231 to 234 arranged along the optical waveguide 21. Nanocarbon material 25 covers optical waveguide 21 and ring resonators 231-234. Similar to FIG. 12B, phase modulation occurs due to changes in the interference state between the light traveling straight through the optical waveguide 21 and the light sequentially passing through the ring resonators 231 to 234.

The phase modulator 20D in FIG. 12D includes an optical waveguide 21 on the input side, an optical waveguide 22 on the output side, and a plurality of ring resonators 231 to 234 arranged in series between the optical waveguide 21 and the optical waveguide 22. . The nanocarbon material 25 is arranged to cover the coupling portion between the series of ring resonators 231 to 234 and the optical waveguides 21 and 22. Due to the change in the refractive index of the ring resonators 231 to 234, the light sequentially transmitted through the ring resonators 231 to 234 undergoes phase modulation.

The phase modulator 20E in FIG. 12E includes a photonic crystal 27 and a nanocarbon material 25 covering the photonic crystal 27. By heating the nanocarbon material 25 by applying electricity through the electrodes 24 and 26, the refractive index of the photonic crystal 27 changes, and the strength of the interaction between light and the medium (slow light effect) changes, resulting in a change in the propagating light. The phase is modulated. Instead of the photonic crystal 27, any nanostructure having a periodic refractive index distribution may be used, and an organic or oriented nanostructure in which a periodic pattern is formed can be used.

The phase modulators 20A to 20E in FIGS. 12A to 12E have higher performance and durability than phase modulators using metal heaters. The nanocarbon material 15 is minute and can be made highly dense, and because of its small heat capacity, even if it is installed adjacent to an optical waveguide or optical resonator, loss is small and high-speed temperature modulation is possible. In addition, the excellent heat conduction properties realize phase modulation operation with high efficiency and low power consumption.

<Third embodiment>
FIG. 13 shows an optical sweeping device 200A using the phase modulator 20 of the second embodiment as an optical device of the third embodiment. The optical sweeping device 200A includes an input waveguide 201, a slab waveguide 202, a plurality of waveguides 203-1 to 203-n connected to the slab waveguide 202, and a plurality of waveguides 203-1 to 203-n. It has phase modulators 20-1 to 20-n. An array waveguide 204 is formed by a plurality of waveguides 203-1 to 203-n. A phase modulator array 205A is composed of a plurality of phase modulators 20-1 to 20-n. Any of the configurations shown in FIGS. 12A to 12E may be adopted as the phase modulators 20-1 to 20-n. By individually controlling the voltage applied to the nanocarbon material 25 of each phase modulator 20, the amount of phase change Δφ ₁ to Δφ _n can be provided.

The output light of each phase modulator 20 constituting the phase modulator array 205A is emitted from the corresponding output light port P1 to Pn.

The light that enters the slab waveguide 202 from the input waveguide 201 is, for example, light of a single wavelength. The incident light from the input waveguide 201 diverges in a fan shape within the slab waveguide 202, is divided into n parts at the output side end face provided in accordance with the fracture surface, and is in phase with the waveguides 203-1 to 203-n. incident at The light propagated through the waveguides 203-1 to 203-n undergoes phase modulation by the phase modulators 20-1 to 20-n. The slab waveguide 202 is an example of a multi-channel optical coupler, and any optical coupler with 1 input and N outputs may be used instead of the slab waveguide 202.

The light is emitted from the output port P in a direction perpendicular to the wavefront (equiphase front). By controlling the phase of the propagating light of each channel with the phase modulators 201-1 to 201-n, the angle of the wavefront can be changed and the light can be emitted in any direction. By continuously changing the phase change amounts Δφ1 to Δφn, the emitted light can be swept in a predetermined direction.

Phase modulators 20-1 to 20-n having optical waveguides formed using nanocarbon material 15 and silicon photonics technology are suitable for high density. By dynamically changing the phase of multi-channel light using phase modulators 20-1 to 20-n, light can be emitted in any direction. The phase modulators 20-1 to 20-n using the nanocarbon material 15 are capable of high-speed phase modulation and achieve high-speed optical sweeping.

FIG. 14 shows the configuration of a phase modulator array 205B as a modified example of the phase modulator array. The phase modulator array 205B includes a plurality of phase modulators 20-1 to 20-n of different sizes and a nanocarbon material 25 that is commonly used for the phase modulators 20-1 to 20-n.

In the example of FIG. 14, the lengths of the phase modulators 20-1 to 20-n connected to each waveguide 203-1 to 203-n of the array waveguide 204 are different. Different phase changes Δφ ₁ to Δφ _n can be obtained by applying voltage or current to the nanocarbon material 25 via the electrodes 24 and 26 and heating it with electricity.

The plurality of phase modulators 20-1 to 20-n may have the same configuration (size or length). In this case, by varying the size of the area covered by the nanocarbon material 25 in each phase modulator 20, the same effect as the configuration in FIG. 14 can be obtained. For example, by changing the length or area of graphene covering the phase modulator 20 for each channel, the interaction length between channels can be changed, or the amount of heat generated by electrical heating of the nanocarbon material 25 can be changed. A phase difference can be given.

FIG. 15 shows an optical sweeping device 200B of another configuration example. In addition to the phase modulator array 205, the optical sweeping device 200B uses a plurality of phase modulators 208 ₁ to 208 _n connected in multiple stages (cascade) to increase phase modulation efficiency.

The phase modulators 208 ₁ to 208 _n provide the same amount of phase change Δφ ₀ . In this sense, the phase modulators 208 ₁ to 208 _n may be referred to as common phase modulators. The phase modulators 208 ₁ to 208 _n are collectively referred to as "phase modulators 208" as appropriate. The phase modulator 208 may have any of the configurations shown in FIGS. 12A to 12E, and can perform high-speed phase modulation by heating the nanocarbon material 25 with electricity.

A part of the light that has passed through the first stage phase modulator 208 ₁ enters the phase modulator 20-1 from the optical coupler 209-1 and is output to the output port P1. A part of the light that has passed through the second stage phase modulator 208 ₂ enters the phase modulator 20-1 from the optical coupler 209-2 and is output to the output port P2. Thereafter, every time the light passes through each phase modulator 208 up to the n-1 stage, a part of the light is taken out by the optical coupler 209, inputted to the phase modulator 20, and outputted to the arrayed output port P. do. The light that has passed through the n-th stage phase modulator _208n enters the phase modulator 20-n as it is and is output to the output port Pn.

In this configuration, the amount of phase change is cumulatively increased by the common phase modulators 208 ₁ to 208 _n connected in multiple stages, and each of the phase modulators 20-1 to 20-n of the phase modulator array 205 , the amount of phase change is finely adjusted. Since the phase changes each time it passes through the multi-stage phase modulator 208, even if each phase change is small, a large total phase change can be obtained. Even if the modulation performance of each phase modulator 208 is not so high, the optical sweeping device 200B as a whole can achieve large phase modulation. Note that in the optical sweeping device 200B, the phase modulator array 205 for fine phase adjustment is not essential, and the multistage phase modulators 208 ₁ to 208 _n alone operate as an optical sweeping device. In this case, the light extracted by each optical coupler 209 is output as is from the corresponding output port P.

<Fourth embodiment>
FIG. 16 is a schematic diagram of an optical path control device 300, which is an optical device of the fourth embodiment. The optical path control device 300 performs optical path control or routing operation using arrayed phase modulation. The optical path control device 300 includes an input waveguide 301, an array phase modulator 30, array waveguides 302-1 to 302-n connected to the output side of the array phase modulator 30, a slab waveguide 303, and a slab waveguide 303. It has array waveguides 304-1 to 304-n connected to the output side. Each of the array waveguides 304-1 to 304-n is connected to a corresponding output port P1 to Pn.

The array phase modulator 30 includes an array of a plurality of phase modulators using a nanocarbon material, and may employ any of the phase modulator arrays used in the third embodiment, or may employ a multistage connection configuration. Good too. The input waveguide 301 is coupled to each of a plurality of phase modulators constituting the array phase modulator 30 by a multi-channel optical coupler (not shown). A single incident light is divided into n parts and enters each phase modulator.

The array phase modulator 30 controls the phase difference of each channel, and light having phase changes Δφ ₁ to Δφ _n is output to the array waveguides 302-1 to 302-n. The shape of the slab waveguide 303 connected to the array waveguides 302-1 to 302-n is controlled so that the input end and the output end have a predetermined curvature. The light incident on the slab waveguide 303 is focused on a point at the output end depending on the phase of the light, as shown by the broken line. The light propagates to the output port P from the array waveguide 304 coupled to the focal point.

As shown by the bidirectional arrow A in the figure, by controlling the phase given by the array phase modulator 30, the focal point on the output side of the slab waveguide 303 can be swept to an arbitrary position. By controlling the amount of phase change of the array phase modulator 30, the light incident on the slab waveguide 303 can be coupled to the array waveguide 304 of a desired channel. Multi-channel optical path control (routing) that controls the electrical heating of the nanocarbon material used in the array phase modulator 30 using external electrical signals, and couples the incident light to any output port P to control the optical path. will be realized. By using the optical path control device 300, the output ports can be switched at a high speed of several hundred kHz to 1 GHz.

<Fifth embodiment>
FIG. 17 is a schematic diagram of a spectrometer 310, which is an optical device of the fifth embodiment. The spectrometer 3101 uses arrayed phase modulation to extract a desired wavelength from incident light multiplexed with a plurality of wavelengths. By using the phase modulator array of the third embodiment, a spectrometer using a solid-state element can be manufactured.

The spectrometer 310 includes an input waveguide 301, an array phase modulator 30, array waveguides 302-1 to 302n connected to the output side of the array phase modulator 30, a slab waveguide 303, and an output side of the slab waveguide 303. It has an output waveguide 306 connected thereto. Output waveguide 306 is connected to output port Pout.

As the array phase modulator 30, any of the phase modulator array configurations described in the third embodiment may be adopted, or a multistage connection configuration may be used. The array phase modulator 30 is capable of high-speed phase modulation by heating the nanocarbon material 25 with electricity.

The light that enters the array phase modulator 30 from the input waveguide 301 is divided into n parts according to the number of phase modulators configuring the array phase modulator 30, and is phase modulated by each phase modulator, and then transmitted to the array waveguide 302. -1 to 302-n. The light incident on the slab waveguide 303 from the array waveguides 302-1 to 303-n spreads in the slab waveguide 303, but the focal position at the output end differs depending on the wavelength.

Therefore, normally only light of a certain wavelength is coupled to the output waveguide 306 and output from the output port Pout. Here, when the phase of each channel is controlled by the array phase modulator 30 by controlling the energization to the nanocarbon material 25, the position of the focal point depending on the wavelength is changed as shown by the bidirectional arrow B in the figure. Shift overall. By controlling the phase of each channel with the array phase modulator 30, the wavelength of light emitted from the output port Pout can be arbitrarily selected, and functions as a spectrometer 310 that extracts a specific wavelength. The spectrometer 310 can be used for applications that require spectroscopy, such as selection of a specific wavelength in wavelength division multiplexing (WDM) optical communication, and spectroscopy in an analyzer. By sequentially changing the amount of phase change in the array phase modulator 30, light of a plurality of wavelengths can be sequentially output from the output port Pout.

<Application to light detection and ranging equipment>
FIG. 18 is a schematic diagram of a light detection and ranging device to which the light sweeping device described in the third embodiment is applied. Object detection and ranging technology using light is called LiDAR (Light Detection and Ranging), and the device shown in FIG. 18 is called a LiDAR device 400.

LiDAR device 400 includes a light projector 410, a light receiver 420, and a control circuit 430. The light projector 410 includes a light source 411, a light source drive circuit 412, a light sweep device 413, and a light sweep drive circuit 414. As described with reference to FIGS. 13 to 15, the optical sweeping device 413 has an array phase modulator composed of an array of a plurality of phase modulators, and the amount of phase change of each phase modulator is nanometer. Controlled by heating the carbon material with electricity.

Light output from the light source 411 is coupled to the optical sweeping device 413 using a coupling lens (not shown) or the like. The optical sweep device 413 applies a drive signal input from the optical sweep drive circuit 414 to the nanocarbon material to control the amount of phase change, and the light Lout output from the output optical port Pout is indicated by a bidirectional arrow BS. Scan (sweep) within a predetermined angular range. By scanning the beam, an object 2 existing within the range of the beam scanning angle is detected, and the distance to the detected object 2 can be measured.

The light receiving unit 420 includes a light receiving element such as a photodiode (PD), and detects the scattered light Lscatter reflected from the object 2. The light projecting section 410 and the light receiving section 420 are arranged close to each other, and their optical axes can be considered to be in a coaxial relationship from a distance of several meters or more. Since the optical sweeping device 413 uses the nanocarbon material 25 and a phase modulator array miniaturized by silicon photonics technology, the light projecting section 410 can be formed as a small chip.

Of the scattered light Lscatter from the object 2, a light component that returns along the same optical path as the light output from the light sweeping device 413 is detected by the light receiving unit 420.

The control circuit 430 measures the angle θ and distance of the object 2 in the XY plane based on the detection result by the light receiving unit 420. The distance to the object 2 can be determined by, for example, the time of flight (TOF) method. Regarding the angle φ in the Z direction perpendicular to the XY plane, the light can be swept at the angle φ in the YZ plane using an optical antenna described later with reference to FIG. By measuring the exit angle θ in the XY plane and the angle φ in the Z direction, the three-dimensional position of the object 2 can be measured, and by combining the distances determined by the time-of-flight method, the position of the object 2 can be determined. Three-dimensional positions can be measured with higher accuracy.

In general LiDAR devices, light sweeping by motor drive is the mainstream, but light sweeping by motor drive is slow and large, and easily broken by external vibrations. A mechanically driven element on a chip such as a MEMS (Micro Electro Mechanical System) is sometimes used as an optical sweeping device, but this also has the problem of being expensive and easily broken by vibration. In contrast, the LiDAR device 400 of the embodiment uses an optical sweeping device 413 that combines nanocarbon material and silicon photonics technology, and is capable of high-speed optical sweeping with a fine configuration.

<Example of application to optical antenna>
19A and 19B show, as an application example of the optical device of the embodiment, a configuration example of an optical antenna that combines a nanostructure whose refractive index periodically changes and a nanocarbon material. FIG. 19A shows an optical antenna 500A using a photonic crystal as a nanostructure whose refractive index changes periodically, and FIG. 19B shows an optical antenna 500B using a grating.

In FIG. 19A, an optical antenna 500A includes a photonic crystal 502 connected to an optical waveguide 501 and a nanocarbon material 15 covering the photonic crystal 502. The nanocarbon material 15 is energized and heated by an electric signal inputted through a pair of electrodes 506 and 508, and the slow light effect of the photonic crystal 502 is controlled to control the light emission direction in the YZ plane. can.

In FIG. 19B, optical antenna 500B has a grating 503 connected to optical waveguide 501 and nanocarbon material 15 covering grating 503. The nanocarbon material 15 is energized and heated by an electric signal inputted through a pair of electrodes 506 and 508, and the refractive index of the grating 503 is modulated to control the direction of light emission in the YZ plane.

The optical antenna 500A or 500B can be used at the output port Pout of the optical device of the first to fifth embodiments. Further, the optical antenna 500A or 500B may be used at the output port of the optical sweeping device 413 of the LiDAR device 400 in FIG. 18. When the LiDAR device 400 of FIG. 18 is configured using the optical antenna 500A or 500B, it is possible to measure the position not only in the XY plane but also in the Z direction, so it is possible to measure the position of a three-dimensional object. Even when using the TOF method, the position of a three-dimensional object can be measured by measuring angles and distances within the XYZ plane.

When the optical antenna 500A of FIG. 19A or the optical antenna 500B of FIG. 19B is not used, a coupling structure such as a spot size converter can be provided at the end face or its tip of the output waveguide as the output port of the optical device, and light can be emitted in the in-plane direction of the substrate (parallel to the substrate surface).

By using the optical antenna 500A or 500B, light can be emitted in the Z direction perpendicular to the substrate surface (XY plane). By optimizing the structure of the grating 503, it is also possible to selectively emit light in a specific direction. When the refractive index and slow light effect are continuously changed by electrically heating the nanocarbon material 15, the light output from the output port Pout can be swept.

Although the present invention has been described above based on specific embodiments, the present invention includes various applications and modifications. The optical device of the embodiment can be applied to various information communication devices such as an optical communication element, an optical interconnect, an integrated optical/electronic circuit, a quantum computer, and a quantum cryptographic device. It can be applied not only to current optical communications and LiDAR technologies, but also to next-generation high-density information communications and quantum information technology.

In the arrayed waveguides used in FIGS. 13 to 17, the lengths of the waveguides in each channel are approximately equal in the figures for simplicity, but the lengths of the waveguides can also be changed for each channel. By changing the optical path length between channels, the delay time and phase difference can be changed, so that higher-order light can be used at the output port Pout, for example.

The optical path control device 300 in FIG. 16 has been described assuming incident light of a single wavelength, but if the incident light is a WDM signal, it can also be used as a demultiplexer that separates each wavelength. In the optical antenna of FIG. 19A or 19B, the nanostructure having a periodic refractive index change is not limited to a photonic crystal or a grating, but may be an inorganic or organic material in which a periodic refractive index distribution is artificially formed. Materials may also be used.

This application claims priority based on Japanese Patent Application No. 2018-097462 filed on May 21, 2018, and includes the entire contents thereof.

10, 10A, 10B, 10C, 10D: Optical path converter (optical device)
11, 12, 21: Optical waveguide 13: Optical resonator (optical component)
14, 16, 24, 26: Electrodes 15, 25: Nanocarbon material 20, 20A to 20E, 20-1 to 20-n: Phase modulators 23, 231 to 234: Ring resonator 30: Array phase modulator 170 Direction Sex coupler (optical parts)
180 Multimode coupler (optical component)
200A, 200B: Optical sweep device (optical device)
201, 301: Input waveguide 203-1 to 203-n: Waveguide 204: Array waveguide 300: Optical path control device (optical device)
306: Output waveguide 310: Spectrometer 400: LiDAR device (light detection and ranging device)
500A, 500B: Optical antenna (optical device)
MZ Mach-Zehnder interferometer (optical parts)
Pin: Incident light port Pout1: Transmitted light output port Pout2: Branched light output port PoutA, PoutB, Pout11, Pout12, P1 to Pn: Output light port

Claims (14)

a first optical waveguide connected to the input optical port;
a second optical waveguide connected to the first output optical port;
a third optical waveguide connected to the second output optical port;
an optical component that optically couples incident light propagating through the first optical waveguide to at least one of the second optical waveguide and the third optical waveguide;
a nanocarbon material disposed at least in an area where the optical component is provided;
an electrode pair that heats the nanocarbon material with electricity;
An optical device characterized in that the optical path is switched between the first output light port and the second output light port by the electrical heating of the nanocarbon material. The first optical waveguide and the second optical waveguide are one continuous waveguide,
The optical component is an optical resonator disposed between the one waveguide and the third optical waveguide,
2. An optical path is switched between the first output light port and the second output light port by the electrical heating of the nanocarbon material covering at least the optical resonator. optical device. The optical component is a Mach-Zehnder interferometer,
the input light port is optically coupled to one end of the Mach-Zehnder interferometer;
The first output light port and the second output light port are optically coupled to the other end of the Mach-Zehnder interferometer,
a first nanocarbon material disposed on one arm of the Mach-Zehnder interferometer;
a second nanocarbon material disposed on the other arm of the Mach-Zehnder interferometer;
has
The energization state of the first nanocarbon material and the energization state of the second nanocarbon material are individually controlled, and the optical path is formed between the first output light port and the second output light port. The optical device according to claim 1, characterized in that it is switchable. The optical component is a directional coupler, a multimode coupler, or a Y splitter,
the incident light port is optically coupled to an input end of the coupling part of the optical component;
The first output light port and the second output light port are each optically coupled to an output end of the coupling portion,
By the electrical heating of the nanocarbon material covering at least the bonding portion, the interference state at the bonding portion changes, and the optical path is changed between the first output light port and the second output light port. The optical device according to claim 1, characterized in that it is switchable. one of the electrode pair is arranged on one side of the optical component, and the other of the electrode pair is arranged on the other side of the optical component,
5. The nanocarbon material covering the bonding portion has a planar shape that is asymmetric with respect to the optical axis of the optical component between the one electrode pair and the other electrode pair. optical device. an optical coupler that branches incident light into multiple channels;
a plurality of phase modulators respectively provided in the plurality of channels;
a plurality of output optical ports coupled to outputs of the plurality of phase modulators;
has
Each of the plurality of phase modulators has a covering region covered with a nanocarbon material, and a different amount of phase change is given to the light passing through each of the plurality of phase modulators by heating the nanocarbon material with electricity,
The direction of the output light emitted from the plurality of output light ports is determined by the phase difference given by the plurality of phase modulators,
The plurality of phase modulators are arranged in parallel or in an array,
Each phase modulator has the covered region individually covered with the nanocarbon material, and the amount of phase change due to electrical heating of the nanocarbon material is individually controlled for each covered region, and each phase An optical device characterized in that the emitted light is swept at a predetermined angle in an in-plane direction of a phase modulator array by continuously changing the amount of phase change due to the electrical heating in the modulator. an optical coupler that branches incident light into multiple channels;
a plurality of phase modulators respectively provided in the plurality of channels;
a plurality of output optical ports coupled to outputs of the plurality of phase modulators;
has
Each of the plurality of phase modulators has a covering region covered with a nanocarbon material, and a different amount of phase change is given to the light passing through each of the plurality of phase modulators by heating the nanocarbon material with electricity,
The direction of the output light emitted from the plurality of output light ports is determined by the phase difference given by the plurality of phase modulators,
The plurality of phase modulators are arranged in parallel or in an array,
The nanocarbon material is provided in common to the plurality of phase modulators so as to cover the entire array , and
The shape or size of the covered area of the portion of each phase modulator covered with the nanocarbon material is different among the plurality of channels, and the shape or size of the covered area of the portion covered with the nanocarbon material is different between the plurality of channels, and the difference between the nanocarbon material and the light is different between the plurality of channels. An optical device characterized in that the different amounts of phase change are provided by changing the interaction length or the amount of heat generated by the electrical heating. a plurality of second phase modulators arranged in front of the plurality of phase modulators arranged in parallel or in an array, connected in series or in multiple stages, and having the same amount of phase change;
It further has
8. The optical device according to claim 6, wherein a part of the incident light is extracted at a stage subsequent to the plurality of phase modulators and coupled to the plurality of output light ports. Each of the plurality of phase modulators includes an optical waveguide, one or more optical resonators, a combination of the optical waveguide and the optical resonator, or a phase modulator formed of a nanostructure having a periodic refractive index distribution. has
The optical device according to any one of claims 6 to 8 , wherein the phase modulation section is coated with the nanocarbon material. An optical coupler that splits incident light into multiple channels, multiple phase modulators provided in each of the multiple channels, and a nanometer that changes the phase of the light passing through each channel by electrical heating using an external electrical signal. an array phase modulator having a carbon material;
a plurality of array waveguides connected to the output of the array phase modulator;
a condensing waveguide connected to the plurality of array waveguides and condensing output light from the plurality of array waveguides at a predetermined position;
an output light port connected to the output of the light collecting waveguide;
has
The amount of phase change of the plurality of phase modulators is controlled by the electrical heating of the nanocarbon material by the electric signal, and the light focusing position at the output end of the light focusing waveguide is switched. device. a plurality of output waveguides connected to the output end of the light collecting waveguide;
It further has
The output optical port includes a plurality of output optical ports connected to each of the plurality of output waveguides,
By controlling the amount of phase change by the electrical heating, the light focusing position is aligned with one of the plurality of output waveguides, and one output light port is selected from the plurality of output light ports. The optical device according to claim 10 . a single output waveguide connected to the output end of the light collection waveguide;
It further has
The output optical port is a single output optical port connected to the output waveguide,
the incident light includes a plurality of wavelengths;
11. The control of the amount of phase change by the energization heating shifts the focusing position depending on the wavelength, and light of a specific wavelength is extracted from the output waveguide. optical device. The output light port includes a nanostructure having a periodic refractive index distribution, a second nanocarbon material covering the nanostructure, and an electrode for inputting an electric signal to heat the second nanocarbon material. and an optical antenna having
Claims 10 to 12 wherein the refractive index of the nanostructure or interaction with propagating light is modulated by the electrical heating of the second nanocarbon material, thereby changing the exit direction of the light incident on the nanostructure . The optical device according to any one of the above . a light projecting unit that sweeps the light emitted from the plurality of light emitting ports within a predetermined angular range using the optical device according to any one of claims 6 to 9 ;
a light receiving unit that receives reflected light from an object existing within the predetermined angular range;
a control circuit that measures a distance to the object based on a result of light reception by the light receiving section;
A light detection and ranging device having:

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