WO2019225445A1

WO2019225445A1 - Optical device using nanocarbon material

Info

Publication number: WO2019225445A1
Application number: PCT/JP2019/019366
Authority: WO
Inventors: 英之牧
Original assignee: 学校法人慶應義塾
Priority date: 2018-05-21
Filing date: 2019-05-15
Publication date: 2019-11-28
Also published as: JP7454852B2; JPWO2019225445A1

Abstract

The present invention provides an optical device which is capable of operating at high speed. An optical device according to the present invention comprises: a first optical waveguide which is connected to an input light port; a second optical waveguide which is connected to a first output light port; a third optical waveguide which is connected to a second output light port; an optical component which optically connects the first optical waveguide to at least one of the second optical waveguide and the third optical waveguide; a nanocarbon material which is provided at least in an area where the optical component is arranged; and a pair of electrodes which apply an electrical signal to the nanocarbon material. The optical path is switched between the first output light port and the second output light port by means of application of an electrical signal.

Description

Optical devices using nanocarbon materials

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

A light emitting element, a light source, and a photocoupler using nanocarbon materials such as graphene and carbon nanotubes (CNT) have been proposed (for example, see Patent Document 1 and Patent Document 2). The nanocarbon material can be heated by energization at high speed, and a continuous spectrum (white light) can be obtained in a wide wavelength range by black body radiation.

On the other hand, silicon photonics technology that integrates optical circuits with fine silicon waveguides on a substrate is attracting attention. Silicon photonics technology is used in various fields, and many compact optical modules and the like used in optical communication networks of the WDM (Wavelength-Division-Multiplexing) system have been developed.

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

Patent No. 5747334 Japanese Patent No. 6155012

In an optical switch and an optical path conversion element in an optical integrated device, switching by a thermo-optic effect is generally performed using a metal or semiconductor heater. When a metal or semiconductor heater is used, the switching speed due to a temperature change in the heater is very slow, on the order of kilohertz (kHz), and the structure is complicated. When a heater is brought close to the optical waveguide in order to improve the performance of the element, the loss of the waveguide increases due to light absorption by the heater. Therefore, there is a problem that a certain distance is provided between the waveguide and the heater, the switching efficiency is low, and the power consumption is high.

An object of the present invention is to provide an optical device capable of high-speed operation with low power consumption.

In the embodiment, an optical device using a nanocarbon material such as graphene or carbon nanotube is provided. In the first aspect of the present invention, the optical device comprises:
A first optical waveguide connected to the incident optical port;
A second optical waveguide connected to the first outgoing light port;
A third optical waveguide connected to the second outgoing light 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 in an area where at least the optical component is provided; and
An electrode pair for applying an electrical signal to the nanocarbon material;
The optical path is switched between the first outgoing light port and the second outgoing light port by applying the electrical signal.

In the second aspect of the present invention, the optical device comprises:
An optical coupler for branching incident light into a plurality of channels;
A plurality of phase modulators respectively provided in the plurality of channels;
A plurality of outgoing optical ports coupled to outputs of the plurality of phase modulators;
Have
The plurality of phase modulators have a coating region covered with a nanocarbon material, and the phase of light passing through the plurality of phase modulators is changed by an electrical signal applied to the nanocarbon material from the outside,
The direction of outgoing light emitted from the plurality of outgoing light ports is determined by the phase difference given by the plurality of phase modulators.

In the third aspect of the present invention, the optical device comprises:
An optical coupler for branching incident light into a plurality of channels, a plurality of phase modulators provided in each of the plurality of channels, and a nano that changes the phase of light passing through each channel by energization heating with an external electric signal An array phase modulator having a carbon material;
A plurality of arrayed waveguides connected to the output of the array phase modulator;
A condensing waveguide that is connected to the plurality of arrayed waveguides and condenses output light from the plurality of arrayed waveguides at a predetermined position;
An outgoing light port connected to the output of the condensing waveguide;
Have
A phase change amount of the plurality of phase modulators is controlled by the electrical signal, and a condensing position at the output end of the condensing waveguide is determined.

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

An optical device capable of high-speed operation with low power consumption will be realized. In particular, high-speed optical path switching and optical sweep can be realized.

It is an upper surface schematic diagram of the optical path changer which is an example of the optical device of 1st Embodiment. It is a perspective view of the optical path changer of FIG. 1A. It is the microscopic image before the electrode formation of the produced optical path changer. It is the microscopic image after the electrode formation of the produced optical path changer. It is a microscopic image of the waveguide structure of the produced 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 which shows the experiment of the optical path switching operation | movement of the produced optical path converter. It is an image which shows branch light emission by voltage off. It is an image which shows transmission light emission by voltage ON. It is a figure of the transmitted light spectrum depending on the voltage applied to a graphene. It is a figure which shows the change of the refractive index with respect to the voltage applied to a graphene. It is a figure which shows the change of the refractive index with respect to the electric power applied to a graphene. It is a figure which shows the time change of the transmitted light intensity when a 100-kHz modulation voltage signal is applied to a graphene. It is a figure which shows the time-resolved measurement result of a thermal radiation when a 1 GHz modulation signal is applied to a graphene. It is a figure which shows the structural example of the optical resonator which can be utilized for the optical device of embodiment. It is a figure which shows the structural example of the optical resonator which can be utilized for the optical device of embodiment. It is a figure which shows the structural example of the optical resonator which can be utilized for the optical device of embodiment. It is a figure which shows the structural example of the optical path changer using a Mach-Zehnder interferometer. It is a figure which shows the structural example of the optical path changer using a directional coupler. It is a figure which shows the structural example of the optical path changer using a multi mode coupler. It is a figure which shows the example of arrangement | positioning of an optical waveguide and nanocarbon material. It is a figure which shows the example of arrangement | positioning of an optical waveguide and nanocarbon material. It is a figure which shows the example of arrangement | positioning of an optical waveguide and nanocarbon material. It is a figure which shows the example of arrangement | positioning of an optical waveguide and nanocarbon material. It is a figure which shows the example of arrangement | positioning of an optical waveguide and nanocarbon material. It is a schematic diagram which shows the structural example of the phase modulator which is an example of the optical device of 2nd Embodiment. It is a figure which shows the structural example of the phase modulator which is an example of the optical device of 2nd Embodiment. It is a figure which shows the structural example of the phase modulator which is an example of the optical device of 2nd Embodiment. It is a figure which shows the structural example of the phase modulator which is an example of the optical device of 2nd Embodiment. It is a figure which shows the structural example of the phase modulator which is an example of the optical device of 2nd Embodiment. It is a schematic diagram of the optical sweep device which is an example of the optical device of 3rd Embodiment. It is a figure which shows the structural example of the phase modulator array used with an optical sweep device. It is a figure which shows another example of an optical sweep device. It is a schematic diagram of the optical path control (routing) device which is an optical device of 4th Embodiment. It is a schematic diagram of the spectrometer which is an optical device of 5th Embodiment. It is a schematic diagram of the optical detection and ranging apparatus to which the optical sweep 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.

In the embodiment, an optical device using nanocarbon materials such as graphene and carbon nanotubes is provided. The optical device is an integrated optical device in which a light transmitting material such as silicon, silicon oxide, or silicon nitride is finely processed, and includes an optical path converter, an optical sweep device, a spectrometer, a phase modulator, an optical antenna, and the like.

By providing a heat source by energization heating in an optical waveguide or resonator that has been finely processed from a light-transmitting material, the refractive index can be controlled using the thermo-optic effect, and high-speed optical path switching and light sweeping can be controlled. .

Nanocarbon material is a carbon material of atomic order in which carbon atoms are arranged on a plane with a six-membered ring structure. Nanocarbon has excellent thermal properties, and has a thermal conductivity about 10 times that of copper, which has a high thermal conductivity. In addition, since a device having a minute structure on the atomic order can be manufactured, the heat capacity, which is a physical quantity proportional to the volume, is extremely small. When a nanocarbon material is applied to an optical device, not only can a large temperature change be obtained with very small heat energy, but also the temperature change relaxation time can be reduced in proportion to the heat capacity, and the optical device operates at high speed. Can be developed.

Nanocarbon materials can increase heat conduction by using plasmons in nanocarbon and surface polar phonons of the substrate, and can provide greater heat conduction than semiconductors and metal materials. Using this characteristic, high-speed and high-efficiency temperature modulation is performed.

When performing optical path conversion, optical path control (routing), optical sweep, etc. using nanocarbon materials, high-speed modulation of several hundred kHz or more is possible, and modulation at a maximum speed of gigahertz (GHz) is possible. Compared to conventional optical devices using metal or semiconductor heaters, optical devices capable of high-speed operation about 100 to 1 million times can be realized.

<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 transmission material such as silicon (Si) on the substrate 103, an optical resonator 13 disposed in the vicinity of the

optical waveguides

11 and 12, It has a nanocarbon material 15 that covers the

optical waveguides

11 and 12 and the optical resonator 13. The nanocarbon material 15 is connected to the 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 on which a SiO ₂ layer 102 is formed on a Si substrate 101. When an SOI substrate is used, 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 is incident on the optical waveguide 11 of the optical path converter 10A from the incident light port Pin, the light traveling straight without passing through the optical resonator 13 is emitted from the transmitted light output port Pout1. The light coupled to the optical resonator 13 and circulated is then emitted from the branched light exit port Pout2. Of the optical waveguide 11, the first waveguide from the incident light port Pin to the portion close to the optical resonator 13 and the second waveguide from the portion close to the optical resonator 13 to the transmitted light exit port Pout1 may be used. Good. A portion of the optical waveguide 12 that is close to the optical resonator 13 to the branched light exit port Pout2 may be used as the second optical waveguide. The optical resonator 13 is an example of an optical component that optically connects incident light from the incident light port Pin to the transmitted light output port Pout1 or the branched light output port Pout2.

In normal operation, when monochromatic light such as laser light having a specific wavelength is incident, the wavelength is selected so that light is output only from one of the transmitted light exit port Pout1 and the branched light exit port Pout2. It 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 energization. When the temperature of the nanocarbon material 15 increases, the temperatures of the lower

optical waveguides

11 and 12 and the optical resonator 13 also increase due to heat conduction. With this temperature rise, the effective refractive indexes of the

optical waveguides

11 and 12 and the optical resonator 13 change, and the substantial optical path lengths of the

optical waveguides

11 and 12 and the optical resonator 13 change.

The phase of light propagating through the

optical waveguides

11 and 12 and the optical resonator 13 can be changed depending on whether or not the nanocarbon material 15 is energized. Using this phase change, the output destination of the light incident from the incident light port Pin can be selected 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.

Whether the light is emitted from the transmitted light exit port Pout1 or the branched light exit port Pout2 in a state where the nanocarbon material 15 is not energized can be set by determining the wavelength. In the state where no voltage is applied to the nanocarbon material 15, the temperature of the nanocarbon material 15 does not increase, and light is emitted only from the initially set emission port, for example, the transmitted light emission port Pout1.

When a voltage is applied to the nanocarbon material 15, the temperature of the nanocarbon material 15 rises due to energization heating. The temperature of the lower

optical waveguides

11 and 12 and the optical resonator 13 also rises due to heat conduction, and the refractive indexes of the

optical waveguides

11 and 12 and the optical resonator 13 change due to the thermo-optic effect. Due to the change in refractive index, the phase of the propagating light is shifted and interference occurs, and the output port is switched to the branched light output port Pout2. The optical path can be converted by an electrical signal applied to the nanocarbon material 15, and the optical path converter 10A operates.

2A to 2C are microscopic images of the optical path changer 10A 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 a waveguide structure in the vicinity of the optical resonator 13. Here, two

optical waveguides

11 and 12 are arranged adjacent to the racetrack type optical resonator 13. Graphene, which is a nanocarbon material 15, is formed on a Si thin line optical circuit including the optical resonator 13 and the

optical waveguides

11 and 12, and electrodes are disposed on both ends of the graphene.

An optical path changer 10A that operates at a high speed with a size of 10 μm × 10 μm can be realized by combining the nanocarbon material 15 and an optical circuit of Si thin wire.

FIG. 3A is a simulation result of a change in light transmittance when the wavelength of light incident from the incident light port Pin is changed in the manufactured optical path converter 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. The wavelength dependence of is shown. Depending on the wavelength of the incident light, the intensity of the transmitted light and the intensity of the branched light change periodically. When the transmitted light intensity is high, the branched light intensity is low, and when the transmitted light intensity is high, 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 periodically changes depending on the wavelength. It is shown that the optical path changer 10A can be controlled by changing the light interference state. FIG. 3B shows the transmitted light emission state of FIG. 3A, and FIG. 3C shows the branched light emission state. In the transmitted light emission state, the input light travels straight through the waveguide toward the transmitted light output port Pout1. In the branched light emission state, incident light is coupled to the ring resonator, and is coupled to the other waveguide from the ring resonator toward the branched light emission port Pout2.

FIG. 4A is a diagram for explaining an experiment for actually performing an optical path conversion operation on the manufactured optical path converter 10A, and is an optical microscope image (including a partially enlarged image) after the electrodes of the optical path converter 10A are formed. . The voltage application to the graphene that is the nanocarbon material 15 is switched to switch the exit port between Pout1 and Pout2. 4B is an infrared camera image when no voltage is applied (V = 0V), and FIG. 4C is an infrared camera image when a voltage is applied (V = 3.5V).

The light incident from the incident light port Pin is divided into light that travels straight through the transmission optical waveguide and branch light that is coupled to the branch optical waveguide through the ring resonator. In this configuration example, a wavelength at which only branched light is obtained in a state where no voltage is applied to the graphene (V = 0V) is selected, and light is propagated toward the branched light exit port in FIG. 4B. Observed. In FIG. 4C, a voltage is applied to the graphene (V = 3.5 V), the optical path is switched from the branched light side to the transmitted light side, and it is observed that light propagates to the transmitted light exit port. It has been demonstrated that an optical path converter 10A that operates at high speed is realized by using a graphene heater.

FIG. 5 shows the voltage dependence of the transmittance spectrum in the optical path converter 10A of the embodiment. By changing the voltage applied to the graphene that is the nanocarbon material 15 to 0 V, 1 V, 2 V, and 3 V, the peak of the transmittance spectrum is shifted to the longer wavelength side. The effective optical path length changes due to the change in the effective refractive index of the Si waveguide due to the thermo-optic effect caused by the current heating to the graphene, and the interference condition of the light passing through the

optical waveguides

11 and 12 and the optical resonator 13 changes. Change. The transmittance spectrum changes due to the change in the interference condition, and the optical paths of the transmitted light and the branched light are switched.

FIG. 6A shows the change in the refractive index of the Si waveguide with the applied voltage to the graphene, and FIG. 6B shows the change in the refractive index of the Si waveguide with the electric power. The refractive index of the Si waveguide can be obtained from the transmittance spectrum of FIG. The electric power is obtained by measuring a current when a voltage is applied. In the samples used in FIGS. 6A and 6B, the refractive index changes substantially linearly with respect to the power. Since how the refractive index of the optical waveguide changes depends on the material used for the optical device and the device structure, the dependence of the refractive index on the electrical external input can be designed according to the application.

FIG. 7 shows the measurement result of the transmitted light intensity at the transmitted light output port Pout1 when a modulation signal of 100 kHz is applied to the

electrodes

14 and 16 of the optical path changer 10A produced in FIG. Graphene is used as the nanocarbon material, and the modulation signal is a rectangular wave signal that varies between 0V and 3.5V. The change in transmitted light intensity was measured with an oscilloscope. Fast optical path selection or optical path switching is observed in real time.

FIG. 8 shows the results of time-resolved measurement of thermal radiation when a 1 GHz modulation signal is input to graphene. The nanocarbon material 15 has a minute structure on the order of atoms, has a small heat capacity, and can perform temperature modulation at high speed. In addition, the nanocarbon material 15 has a thermal conductivity about 10 times that of copper, which is said to have a high thermal conductivity, and further, using plasmons in the nanocarbon and surface polar phonons of the substrate, Furthermore, a larger thermal conductivity can be obtained. By using the nanocarbon material 15, a large temperature change can be obtained with small thermal energy. In addition, even when a high-speed voltage signal of 1 GHz is input, the graphene temperature changes following the speed of the modulation signal even when the temperature change relaxation time is short.

8 shows that the optical path changer 10A of the embodiment can operate at a maximum speed of 1 GHz. The optical path changer 10A can operate at a speed 100 to 1 million times higher than when a metal or semiconductor heater is used.

7 and 8 are applicable to the case where carbon nanotubes (CNT) are used as the nanocarbon material 15. As the CNT, either single-wall CNT or multilayer CNT may be used. Depending on the structure (chirality) of CNT, there are semiconductor nanotubes and metal nanotubes, both of which can be used. CNTs can be formed by various methods such as a chemical vapor deposition (CVD) method and a high pressure carbon monoxide (HiPCO) method.

When the CNTs are arranged on the

optical waveguides

11 and 12 and the optical resonator 13, the CNT solution may be spin-coated or dip-coated, or transferred with a tape, gel, or polymer. Further, CNTs may be directly grown in the region including the

optical waveguides

11 and 12 and the optical resonator 13 by the CVD method. One CNT carbon nanotube may be used, but a larger change in refractive index can be obtained by using many CNTs. Therefore, it is effective to use a CNT thin film obtained by thinning CNTs into a network. Also when graphene is used for the nanocarbon material 15, the number of graphene layers is arbitrary, and may be any of a single layer, two layers, several layers, and multiple layers. Regardless of the growth method of graphene, any method such as CVD, mechanical peeling, transfer or direct growth can be used.

The nanocarbon material 15 can be electrically heated with a thinness of atomic order. When an atomic order thin film is formed using a normal metal material and energized and heated, the metal breaks due to heating or migration, and the optical device cannot be operated. Since the nanocarbon material 15 has a covalent bond and is resistant to energization heating, the nanocarbon material 15 hardly breaks due to energization heating despite the atomic order structure, and has high durability. By combining silicon photonics technology and nanocarbon materials, it is possible to form optical path converters with fine structures at high density.

The nanocarbon material 15 has a unique electronic state due to its minute structure, and this electronic state works favorably for an optical device. For example, in the case of graphene, the energy dispersion of electrons is linear, and light absorption can be controlled by an electric field or a doping state. Since light absorption can be suppressed by selecting an electric field and a doping state, even if the nanocarbon material 15 is disposed immediately above the

optical waveguides

11 and 12 and the optical resonator 13, unlike an ordinary metal, light loss due to absorption is lost. Can be kept low. In the case of CNT, there is an effect similar to that of graphene. Light absorption can be controlled by an electric field or doping, and if semiconductor CNT is used, light absorption can be further suppressed.

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

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, it may have any shape as long as it functions as the optical resonator 13, and the circular ring resonator 132 shown in FIG. 9B or the disk type resonator 133 shown in FIG. 9C. Etc. may be used.

FIG. 10A shows an optical path converter 10B as a modification of the optical device of the first embodiment. The optical path converter 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. A nanocarbon material 15 </ b> A is disposed on the optical waveguide 11, and a voltage (or current) is applied to the nanocarbon material 15 </ b> A by the electrode 141 and the electrode 161. The nanocarbon material 15B is disposed on the optical waveguide 12, and a voltage (or current) is applied to the nanocarbon material 15B by the electrode 142 and the electrode 162. The first optical waveguide from the incident optical port Pin to the optical coupler 17, the second optical waveguide from the optical coupler 19 to the outgoing optical port PoutA, and the third optical waveguide from the optical coupler 19 to the outgoing optical port PoutB It is good. The Mach-Zehnder interferometer MZ is an optical component that optically connects 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 voltage application 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 energized and heated, or both may be energized and heated.

When a voltage is applied, the phase of light changes in the two

optical waveguides

11 and 12 of the Mach-Zehnder interferometer MZ due to a change in refractive index 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 are configured such that two waveguides approach each other and are coupled by evanescent (near field), but any type of optical coupler can be used. For example, a multi-mode interference system (MMI: Multi-Mode Interference) 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 at predetermined positions. The nanocarbon material 15 is disposed so as to cover the adjacent portion. The light incident from the incident light port Pin interferes with each other in the evanescent field at the adjacent portion, and the light is distributed to the two output-

side waveguides

171 and 172 connected to the output light ports Pout11 and Pout12, respectively. The distribution ratio is adjusted by energization heating to the nanocarbon material 15 covering the adjacent portion. Since the interference state is changed by energizing and heating the nanocarbon material 15 and the intensity of the light of the two outgoing lights is changed, the output from the outgoing light ports Pout11 and Pout12 is switched by energizing the nanocarbon material 15. Can do. The formed nanocarbon material 15 may have a structure that is symmetric with respect to the optical axis (propagation axis), or may have a temperature gradient with an asymmetric structure with respect to the optical axis by making the shape of graphene trapezoidal 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. The multimode coupler 180 is a 1-input 2-output multimode coupler. Instead of the multimode coupler 180, a Y splitter may be used. The multimode coupler 180 has a structure in which one input waveguide 181 and two

output waveguides

182 and 183 are connected to the slab portion 184. The slab portion 184 is a coupling portion that couples light propagating through the input waveguide 181 to the

output waveguide

182 or 183. In the slab portion 184 having a constant width, incident light is converted into a plurality of propagation modes and coupled to the

output waveguide

182 or 183. When using a Y-splitter, the

waveguides

181, 182 and 183 are directly coupled.

The light incident from the incident light port Pin is distributed by optical interference in the slab part 184, and the ratio of the light intensity emitted from the outgoing light port Pout11 and the outgoing light port Pout12 varies depending on the interference state of the slab part 184. be able to. By disposing the nanocarbon material 15 on the slab portion 184 and energizing and heating, the interference state changes, and the light intensity of the two outgoing light ports Pout11 and Pout12 can be switched. The nanocarbon material 15 to be formed may have a symmetric structure with respect to the optical axis, but the shape of the nanocarbon material 15 is trapezoidal as shown in FIG. Also good.

<Arrangement example of nano carbon material>
11A to 11E show examples of arrangement of the nanocarbon material 15 with respect to an optical waveguide or an optical resonator (hereinafter abbreviated as “optical waveguide 111”). In FIG. 11A, the optical waveguide 111 is formed on the main surface of the substrate 110, and the nanocarbon material 15 is disposed so as to cover the upper surface and the side surface 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 upper surface of the optical waveguide 111. In the case of the embedded optical waveguide 111, the substrate surface is flat, and the arrangement of the nanocarbon material 15 is easy. 11A and 11B, at least a part of the optical waveguide 111 may be in contact with the nanocarbon material 15.

When the optical waveguide 111 is covered with the nanocarbon material 15 as shown in FIG. 11A and FIG. 11B, the optical path control directly affects the temperature rise of the nanocarbon material 15 through the evanescent light generated around the optical waveguide 111. Can be used. 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 increased with high efficiency. 11A and 11B realizes high-efficiency optical path switching control with low power consumption.

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

11C and 11D, when the cap layer 112 or the lower cap layer 113 is inserted between the optical waveguide 111 and the nanocarbon material 15, these cap layers are formed of a material having a lower refractive index than that of the optical waveguide 111. Then, it may 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 due to the arrangement of the nanocarbon material 15 on the optical waveguide 111 is minimized, and the optical path converter 100A (or 100B) Loss can be reduced.

The thickness of the cap layer 112 or the lower cap layer 113 can be designed to an optimum thickness in consideration of the heating efficiency of the nanocarbon material 15 and the optical waveguide 111 and the loss due to the nanocarbon material 15. Depending on the material of the cap layer 112 or the lower cap layer 113, the heat conduction from the nanocarbon material 15 to the optical waveguide 111 changes. Therefore, the optical path conversion performance is changed by selecting the material of the cap layer 112 or the lower cap layer 113. You can also

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

The cap layer 112, the lower cap layer 113, and the upper cap layer 115 are preferably made of a material having 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 configuration 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 substance (polar crystal) having a polarity 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. May be. In this case, the surface polar phonon of the polar substance allows the heat to escape quickly (see arrow h in the figure), enables a fast temperature change, and improves the switching speed. As the polar substance, a substance such as silicon oxide, silicon nitride, boron nitride, alumina, hafnium oxide, etc., that has polarity between atoms constituting the substance and can induce polar phonons can be selected. Since polar phonons generated on the surface are used, the polar substance to be formed may be very thin, and even if it is formed on the nanometer order, it functions sufficiently.

Second Embodiment
12A to 12E show phase modulators 20A to 20E using nanocarbon as optical devices of the second embodiment, respectively. The phase modulator 20A in FIG. 12A applies a 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.

Electrodes

24 and 26. The operating principle of the phase modulator 20A utilizes the change in the refractive index of the optical waveguide 21 caused by energizing and heating the nanocarbon material 25, as described in the first embodiment. The change in the refractive index of the optical waveguide 21 changes the propagation speed of light and changes the phase.

The phase modulator 20B in FIG. 12B has one ring resonator 23 disposed adjacent to the optical waveguide 21 in addition to the configuration in FIG. 12A. The nanocarbon material 25 covers the ring resonator 23 and the 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 due to current heating to the nanocarbon material 25, the interference state 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 is changed. Changes.

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

The phase modulator 20D of FIG. 12D includes an input-side optical waveguide 21, an output-side optical waveguide 22, 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 disposed so as 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, light sequentially transmitted through the ring resonators 231 to 234 undergoes phase modulation.

12E has a photonic crystal 27 and a nanocarbon material 25 that covers the photonic crystal 27. By energizing and heating the nanocarbon material 25 via the

electrodes

24 and 26, the refractive index of the photonic crystal 27 changes, the strength of the interaction between light and the medium (slow light effect) changes, and the propagation light propagates. The phase is modulated. Instead of the photonic crystal 27, an arbitrary 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.

12A to 12E have higher performance and durability than the phase modulator using a metal heater. The nanocarbon material 15 is minute and can be increased in density, and since the heat capacity is small, even if it is installed adjacent to an optical waveguide or an optical resonator, loss is small and high-speed temperature modulation is possible. In addition, the phase modulation operation with high efficiency and low power consumption is realized by good heat conduction characteristics.

<Third Embodiment>
FIG. 13 shows an optical sweep device 200A using the phase modulator 20 of the second embodiment as the optical device of the third embodiment. The optical sweep 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 connected to the waveguides 203-1 to 203-n. Phase modulators 20-1 to 20-n. An arrayed waveguide 204 is formed by the plurality of waveguides 203-1 to 203-n. A phase modulator array 205A is configured by an array of a plurality of phase modulators 20-1 to 20-n. As the phase modulators 20-1 to 20-n, any of the configurations shown in FIGS. 12A to 12E may be adopted. By individually controlling the voltage applied to the nanocarbon material 25 of each phase modulator 20, the phase change amounts Δφ ₁ to Δφ _n can be given.

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

The light incident on the slab waveguide 202 from the input waveguide 201 is, for example, light having a single wavelength. Incident light from the input waveguide 201 diverges in a fan shape in the slab waveguide 202 and is divided into n 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 is subjected to 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 an arbitrary optical coupler with one input and N outputs may be used instead of the slab waveguide 202.

The light exits from the exit port P in the direction perpendicular to the wavefront (equal phase plane). By controlling the phase of the propagation light of each channel with the phase modulators 201-1 to 201-n, it is possible to emit light in an arbitrary direction by changing the angle of the wavefront. By continuously changing the phase change amounts Δφ1 to Δφn, the emitted light can be swept in a predetermined direction.

The phase modulators 20-1 to 20-n having an optical waveguide formed by the nanocarbon material 15 and silicon photonics technology are suitable for high density. By dynamically changing the phase of multi-channel light by the 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 can perform high-speed phase modulation and realize high-speed optical sweep.

FIG. 14 shows a configuration of a phase modulator array 205B as a modification of the phase modulator array. The phase modulator array 205B includes a plurality of phase modulators 20-1 to 20-n having different sizes and a nanocarbon material 25 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 the waveguides 203-1 to 203-n of the arrayed waveguide 204 are different. By applying voltage or current to the nanocarbon material 25 through the

electrodes

24 and 26 and conducting heating, different phase change amounts Δφ ₁ to Δφ _n can be obtained.

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

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

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

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

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

<Fourth embodiment>
FIG. 16 is a schematic diagram of an optical path control device 300 that is the 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 arrayed waveguides 304-1 to 304-n connected to the output side. Each of the arrayed 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 nanocarbon materials, and any of the phase modulator arrays used in the third embodiment may be adopted, or a multistage connection configuration is used. Also good. 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). The single incident light is divided into n and enters each phase modulator.

The phase difference of each channel is controlled by the array phase modulator 30, and light having phase change amounts Δφ ₁ to Δφ _n is output to the arrayed waveguides 302-1 to 302-n. The shape of the slab waveguide 303 connected to the arrayed waveguides 302-1 to 302-n is controlled so that the entrance end and the exit end have a predetermined curvature. The light incident on the slab waveguide 303 is condensed at one point having an emission end depending on the phase of the light, as indicated by a broken line. Propagation from the arrayed waveguide 304 coupled to the condensing point to the exit port P.

As shown by the two-way arrow A in the figure, by controlling the phase given by the array phase modulator 30, the condensing point on the emission side of the slab waveguide 303 can be swept to an arbitrary position. By controlling the phase change amount of the array phase modulator 30, the light incident on the slab waveguide 303 can be coupled to the arrayed waveguide 304 of a desired channel. Multi-channel optical path control (routing) for controlling the optical path by controlling the energization heating of the nanocarbon material used in the array phase modulator 30 by an external electric signal and coupling the incident light to an arbitrary output port P Is realized. By using the optical path control device 300, the emission port can be switched at a high speed of several hundred kHz to 1 GHz.

<Fifth Embodiment>
FIG. 17 is a schematic diagram of a spectroscope 310 that is an optical device according to the fifth embodiment. The spectroscope 3101 extracts a desired wavelength from incident light in which a plurality of wavelengths are multiplexed, using arrayed phase modulation. By using the arrangement of the phase modulators of the third embodiment, a spectroscope with a solid 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. An output waveguide 306 is connected. The output waveguide 306 is connected to the output port Pout.

As the array phase modulator 30, the configuration of any phase modulator array described in the third embodiment may be adopted, or a multistage connection configuration may be used. The array phase modulator 30 can perform high-speed phase modulation by energizing and heating the nanocarbon material 25.

Light incident on the array phase modulator 30 from the input waveguide 301 is divided into n according to the number of phase modulators constituting the array phase modulator 30, undergoes phase modulation by each phase modulator, and receives the array waveguide 302. -1 to 302-n. The light that has entered the slab waveguide 303 from the arrayed waveguides 302-1 to 303-n spreads in the slab waveguide 303, but the focal position at the exit 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 energization to the nanocarbon material 25 is controlled and the phase of each channel is controlled by the array phase modulator 30, the position of the focal point depending on the wavelength is obtained 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 emission port Pout can be arbitrarily selected and functions as a spectrometer 310 that extracts a specific wavelength. The spectroscope 310 can be used for applications that require spectroscopy, such as selection of a specific wavelength in WDM (Wavelength-Division-Multiplexing) 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 emission port Pout.

<Application to light detection and ranging device>
FIG. 18 is a schematic diagram of a light detection and distance measuring apparatus to which the light sweep device described in the third embodiment is applied. The object detection and ranging technique using light is called LiDAR (Light Detection and Ranging), and the apparatus shown in FIG.

The LiDAR device 400 includes a light projecting unit 410, a light receiving unit 420, and a control circuit 430. The light projecting unit 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 sweep device 413 includes an array phase modulator composed of an array of a plurality of phase modulators. It is controlled by energization heating to the carbon material.

The light output from the light source 411 is coupled to the optical sweep device 413 using a coupling lens (not shown) or the like. The optical sweep device 413 applies the drive signal input from the optical sweep drive circuit 414 to the nanocarbon material to control the phase change amount, and the light Lout output from the output light port Pout is indicated by a bidirectional arrow BS. In this manner, scanning (sweep) is performed within a predetermined angle range. By the beam scanning, the object 2 existing in 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 scattered light Lscatter reflected from the object 2. The light projecting unit 410 and the light receiving unit 420 are arranged close to each other, and the optical axes of the light projecting unit 410 and the light receiving unit 420 can be regarded as having a coaxial relationship from a position several meters away. Since the optical sweep device 413 uses a nano-carbon material 25 and a phase modulator array miniaturized by silicon photonics technology, the light projecting unit 410 can be formed as a small chip.

Among 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 sweep device 413 is detected by the light receiving unit 420.

The control circuit 430 measures the angle θ and the distance in the XY plane of the object 2 based on the detection result by the light receiving unit 420. The distance to the object 2 can be obtained by, for example, a time-of-flight (TOF) method. With respect to the angle φ in the Z direction perpendicular to the XY plane, light can be swept at an angle φ in the YZ plane using an optical antenna described later with reference to FIG. By measuring the emission 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 further, by combining the distances obtained by the time-of-flight method, The three-dimensional position 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 is easily broken by external vibration. A mechanical drive element on a chip such as MEMS (Micro Electro Mechanical System) may be used as the optical sweep device, but this also has a problem that the element is easily broken due to vibration. On the other hand, the LiDAR apparatus 400 according to the embodiment uses an optical sweep device 413 that combines a nanocarbon material and silicon photonics technology, and can perform high-speed optical sweep with a fine configuration.

<Application example to optical antenna>
FIG. 19A and FIG. 19B show a configuration example of an optical antenna in which a nanostructure whose refractive index changes periodically and a nanocarbon material are combined as an application example of the optical device of the embodiment. 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, the optical antenna 500A includes a photonic crystal 502 connected to the 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 input via the pair of

electrodes

506 and 508, the slow light effect of the photonic crystal 502 is controlled, and the light emission direction in the YZ plane can be controlled. it can.

19B, the optical antenna 500B includes a grating 503 connected to the optical waveguide 501 and a nanocarbon material 15 covering the grating 503. The nanocarbon material 15 is energized and heated by an electric signal input via the pair of

electrodes

506 and 508, and the refractive index of the grating 503 can be modulated to control the light emission direction in the YZ plane.

The

optical antenna

500A or 500B can be used for the output port Pout of the optical device of the first to fifth embodiments. Further, the

optical antenna

500A or 500B may be used as the emission port of the optical sweep device 413 of the LiDAR apparatus 400 of FIG. When the LiDAR device 400 of FIG. 18 is configured using the

optical antenna

500A or 500B, not only the XY plane but also the position in the Z direction can be measured, so that the position of a three-dimensional object can be measured. Even when the TOF method is used, the position of a three-dimensional object can be measured by measuring the angle in the XYZ plane and its distance.

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 is provided on the end face of the output waveguide or the tip thereof as the output port of the optical device, and the in-plane direction of the substrate ( Light can be emitted in a direction 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, light can be selectively emitted in a specific direction. When the refractive index and the slow light effect are continuously changed by energization heating of the nanocarbon material 15, light output from the emission port Pout can be swept.

Although the present invention has been described based on the specific embodiments, the present invention includes various application examples and modifications. The optical device according to 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 cryptography device. It can be applied not only to current optical communication and LiDAR technologies, but also to next-generation high-density information communication and quantum information technologies.

The arrayed waveguides used in FIG. 13 to FIG. 17 are depicted with the waveguide lengths of each channel being almost equal in the drawings for simplicity, but the waveguide lengths can be changed for each channel. Since the delay time and the phase difference can be changed by changing the optical path length between channels, for example, higher-order light can be used at the output port Pout.

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

20, 20A to 20E, 20-1 to 20-n:

phase modulator

23, 231 to 234: ring resonator 30: array phase modulator 170 Coupler (optical component)
180 Multi-mode coupler (optical components)
200A, 200B: optical sweep device (optical device)
201, 301: input waveguides 203-1 to 203-n: waveguides 204: arrayed waveguides 300: optical path control devices (optical devices)
306: Output waveguide 310: Spectrometer 400: LiDAR device (light detection and ranging device)
500A, 500B: Optical antenna (optical device)
MZ Mach-Zehnder interferometer (optical components)
Pin: incident light port Pout1: transmitted light exit port Pout2: branch light exit port PoutA, PoutB, Pout11, Pout12, P1 to Pn: exit light ports

Claims

A first optical waveguide connected to the incident optical port;
A second optical waveguide connected to the first outgoing light port;
A third optical waveguide connected to the second outgoing light 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 in an area where at least the optical component is provided; and
An electrode pair for applying an electrical signal to the nanocarbon material;
The optical device is characterized in that an optical path is switched between the first outgoing light port and the second outgoing light port by applying the electrical signal.
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;
The optical path is switched between the first outgoing light port and the second outgoing light port by applying the electrical signal to at least the nanocarbon material covering the optical resonator. The optical device according to.
The optical component is a Mach-Zehnder interferometer;
The incident optical port is optically coupled to one end of the Mach-Zehnder interferometer;
The first outgoing light port and the second outgoing 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;
Have
The current state of the first nanocarbon material and the current state of the second nanocarbon material are individually controlled by the electrical signal, so that the first output light port and the second output light port are connected. The optical device according to claim 1, wherein the optical path is switched.
The optical component is a directional coupler, a multimode coupler, or a Y splitter,
The incident light port is optically coupled to the input end of the coupling portion of the optical component;
The first outgoing light port and the second outgoing light port are optically coupled to the output ends of the coupling parts, respectively.
By applying the electrical signal to the nanocarbon material covering at least the coupling portion, an interference state in the coupling portion changes, and an optical path between the first emission light port and the second emission light port. The optical device according to claim 1, wherein the optical device is switched.
5. The optical device according to claim 4, wherein the nanocarbon material covering the coupling portion has a planar shape asymmetric with respect to the optical axis of the optical component.
An optical coupler for branching incident light into a plurality of channels;
A plurality of phase modulators respectively provided in the plurality of channels;
A plurality of outgoing optical ports coupled to outputs of the plurality of phase modulators;
Have
The plurality of phase modulators have a coating region covered with a nanocarbon material, and the phase of light passing through the plurality of phase modulators is changed by an electrical signal applied to the nanocarbon material from the outside,
An optical device characterized in that a direction of outgoing light emitted from the plurality of outgoing light ports is determined by a 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 by the nanocarbon material;
The optical device according to claim 6, wherein phase change amounts of the plurality of phase modulators are individually controlled by energization heating of the nanocarbon material.
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,
The optical device according to claim 6, wherein a shape or a size of the covering region in which each phase modulator is covered with the nanocarbon material is different among the plurality of channels.
The plurality of phase modulators are connected in series or in multiple stages and have the same amount of phase change,
The optical device according to claim 6, wherein a part of the incident light is extracted after the phase modulator and coupled to the plurality of outgoing light ports.
Each of the plurality of phase modulators is 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 Have
The optical device according to any one of claims 6 to 9, wherein the phase modulation section is coated with the nanocarbon material.
An optical coupler for branching incident light into a plurality of channels, a plurality of phase modulators provided in each of the plurality of channels, and a nano that changes the phase of light passing through each channel by energization heating with an external electric signal An array phase modulator having a carbon material;
A plurality of arrayed waveguides connected to the output of the array phase modulator;
A condensing waveguide that is connected to the plurality of arrayed waveguides and condenses output light from the plurality of arrayed waveguides at a predetermined position;
An outgoing light port connected to the output of the condensing waveguide;
Have
An optical device characterized in that a phase change amount of the plurality of phase modulators is controlled by the electrical signal, and a condensing position at an output end of the condensing waveguide is determined.
A plurality of output waveguides connected to an output end of the condensing waveguide;
Further comprising
The output light port includes a plurality of output light ports connected to each of the plurality of output waveguides,
12. The output light port is selected from the plurality of output light ports by adjusting the phase change amount so that the condensing position is adjusted to one of the plurality of output waveguides. The optical device according to.
A single output waveguide connected to the output end of the condensing waveguide;
Further comprising
The outgoing light port is a single outgoing light port connected to the output waveguide;
The incident light includes a plurality of wavelengths;
The optical device according to claim 11, wherein the condensing position is shifted depending on a wavelength by controlling the phase change amount, and light having a specific wavelength is extracted from the output waveguide.
A light projecting unit that sweeps light emitted from the plurality of outgoing light ports within a predetermined angle range using the optical device according to any one of claims 7 to 10;
A light receiving unit that receives reflected light from an object existing within the predetermined angle range;
A control circuit for measuring the distance of the object based on a light reception result in the light receiving unit;
A light detection and ranging device.
A nanostructure having a periodic refractive index profile;
A nanocarbon material covering the nanostructure;
An electrode for inputting an electrical signal applied to the nanocarbon material;
And the nanocarbon material is heated by energization and heating, whereby the refractive index of the nanostructure or the interaction with propagating light is modulated to change the emission direction of light incident on the nanostructure. device.