Optical switch, ranging device, and electronic apparatus

Abstract

The purpose of the present invention is to provide a technology for shortening the temperature switching speed of a waveguide and improving the switching performance of an optical switch by appropriately controlling a voltage waveform to be applied to a heater.　The present technology provides an optical switch and the like. The optical switch changes the phase of light on the basis of a thermooptic effect, and comprises: a heater that changes the temperature of a region in which the refractive index changes by the thermooptic effect; and a waveform generation unit that generates a voltage waveform for controlling a temporal change in voltage to be applied to the heater. The waveform generation unit changes the voltage from an initial voltage toward a limit voltage (maximum voltage or minimum voltage) in the shortest possible time, and thereafter changes the voltage from the limit voltage toward a target voltage.

Description

Optical switches, distance measuring devices, and electronic equipment

[0001] The technology disclosed herein (hereinafter also referred to as "this technology") relates to optical switches, distance measuring devices, and electronic equipment.

[0002] In silicon photonics devices, optical switching technology using Mach-Zehnder interferometers (MZ interferometers) is employed. Silicon photonics technology is based on optical waveguides with a high refractive index difference, using silicon as the core and quartz as the cladding. High-precision processing technology applying CMOS processes enables the integration of optical and electronic circuits. This technology plays an important role in distance measurement and information transmission in distance measurement systems such as LiDAR (Light Detection and Ranging) and optical communication systems.

[0003] In particular, FMCW (Frequency Modulated Continuous Wave) LiDAR is a technology that measures distance by irradiating an object with laser light and receiving the reflected light from it, and there is a strong demand for improvements in its accuracy and speed. For example, Patent Document 1 discloses a technique for adjusting the phase difference of an MZ interferometer. In optical switches using an MZ interferometer, a method is employed in which the path of light is switched by changing the temperature of the waveguide with a heater and controlling the refractive index.

[0004] Japanese Patent Publication No. 2007-334013

[0005] However, the slow temperature switching speed of the heater limited the potential for improving the LiDAR frame rate. Therefore, faster temperature switching technology is needed. In conventional technology, it takes tens of microseconds for the waveguide temperature to stabilize when the applied voltage to the heater is switched, and this delay hinders improvements in the operating speed of FMCW LiDAR.

[0006] Therefore, the primary objective of this technology is to shorten the temperature switching speed of the waveguide and improve the switching performance of the optical switch by appropriately controlling the voltage waveform applied to the heater.

[0007] This technology provides an optical switch that changes the phase of light based on the thermo-optic effect, comprising: a heater that changes the temperature of a region where the refractive index changes due to the thermo-optic effect; and a waveform generation unit that generates a voltage waveform to control the time change of the voltage applied to the heater, wherein the waveform generation unit changes the voltage from an initial voltage to a limit voltage (maximum or minimum voltage) in the shortest possible time, and then changes the voltage from the limit voltage to a target voltage. The shortest possible time may be 0.01 microseconds or more and 100 microseconds or less. The change in voltage from the limit voltage to the target voltage may be linear. The change in voltage from the limit voltage to the target voltage may be nonlinear. The waveform generation unit may control the voltage waveform such that the change in thermal energy accumulated in the heater and its vicinity is equal to the value obtained by integrating the power corresponding to the voltage applied to the heater over the transition time from the initial voltage to the target voltage. Let u be the thermal energy stored in the heater and its vicinity per unit of power, P1 be the power corresponding to the initial voltage, P2 be the power corresponding to the target voltage, and P2 be the power corresponding to the limit voltage (maximum voltage). Max When the transition time from the initial voltage to the target voltage is denoted as t, the waveform generation unit may generate a voltage waveform that satisfies the following equation (1). Let u be the thermal energy stored in the heater per unit of power, P1 be the power corresponding to the initial voltage, P2 be the power corresponding to the target voltage, and P be the power corresponding to the limit voltage (minimum voltage). Min When the transition time from the initial voltage to the target voltage is t, the waveform generation unit may generate a voltage waveform that satisfies the following equation (2). The optical switch further comprises a power correction unit that corrects the power corresponding to the initial voltage and the power corresponding to the target voltage, and the power correction unit may correct the power by detecting the amount of light based on a change in the phase of light and feeding the detection result back to the waveform generation unit. The power correction unit may be connected between a device that changes the phase of light and an optical antenna, and correct the power by detecting the output light amount of the optical switch and feeding the detection result back to the waveform generation unit. The power correction unit may be connected to an optical antenna connected to a device that changes the phase of light, and correct the power by detecting the amount of light emitted by the optical antenna and feeding the detection result back to the waveform generation unit. The power correction unit may be connected to an optical antenna connected to a device that changes the phase of light, and correct the power by detecting the amount of light received by the optical antenna and feeding the detection result back to the waveform generation unit. The optical switch further comprises an amplitude determination unit that determines the amplitude of the voltage waveform applied to the heater, and the amplitude determination unit may determine the optimal amplitude by stepwise changing the amplitude so that the transition time from the initial voltage to the target voltage is shortest. The amplitude determination unit may be connected between a device that changes the phase of light and an optical antenna, detect the output light amount of the optical switch, and feed the detection result back to the waveform generation unit to determine the optimal amplitude. The amplitude determination unit may be connected to an optical antenna connected to a device that changes the phase of light, detect the amount of light emitted by the optical antenna, and feed the detection result back to the waveform generation unit to determine the optimal amplitude. The amplitude determination unit may be connected to an optical antenna connected to a device that changes the phase of light, detect the amount of light received by the optical antenna, and feed the detection result back to the waveform generation unit to determine the optimal amplitude. The optical switch may comprise a Mach-Zehnder interferometer that changes the phase of light based on the thermo-optic effect. The heater may contain TiN.Furthermore, this technology provides a distance measuring device that includes an optical switch that changes the phase of light based on the thermo-optic effect, the optical switch having a heater that changes the temperature of a region where the refractive index changes due to the thermo-optic effect, and a waveform generation unit that generates a voltage waveform that controls the time change of the voltage applied to the heater, the waveform generation unit changing the voltage from an initial voltage to a limit voltage in the shortest possible time, and then changing the voltage from the limit voltage to a target voltage. Furthermore, this technology provides an electronic device that includes an optical switch that changes the phase of light based on the thermo-optic effect, the optical switch having a heater that changes the temperature of a region where the refractive index changes due to the thermo-optic effect, and a waveform generation unit that generates a voltage waveform that controls the time change of the voltage applied to the heater, the waveform generation unit changing the voltage from an initial voltage to a limit voltage in the shortest possible time, and then changing the voltage from the limit voltage to a target voltage.

[0008] This is a schematic perspective view showing an example configuration of an MZ interferometer. This is a graph showing the applied voltage waveform to a heater according to one embodiment of this technology. This is a schematic diagram showing the configuration of a control system for switching an optical switch according to one embodiment of this technology. This is a graph showing an example of the power waveform supplied to a heater according to one embodiment of this technology. This is a graph showing an example of the power waveform supplied to a heater according to one embodiment of this technology. This is a block diagram showing an example configuration of an optical switch according to one embodiment of this technology. This is a block diagram showing an example configuration of an optical switch according to one embodiment of this technology. This is a block diagram showing an example configuration of an optical switch according to one embodiment of this technology. This is a graph showing the relationship between heater power and light intensity in an optical switch according to one embodiment of this technology. This is a flowchart showing an example of the processing flow of a power correction unit according to one embodiment of this technology. This is a block diagram showing an example configuration of an optical switch according to one embodiment of this technology. This is a block diagram showing an example of the processing flow of an optical switch according to one embodiment of this technology. This is a block diagram showing an example of the processing of an amplitude determination unit according to one embodiment of this technology. This is a graph showing an example of the processing of an amplitude determination unit according to one embodiment of this technology. This is a graph showing the characteristics of an optical switch. This is a block diagram showing an example configuration of a distance measuring device according to one embodiment of this technology. This is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile control system to which this technology may be applied. This is a diagram showing an example of the installation position of the imaging unit.

[0009] Hereinafter, preferred embodiments for implementing this technology will be described with reference to the drawings. The embodiments described below are merely examples of typical embodiments of this technology and do not limit the scope of this technology. Furthermore, this technology can be implemented by combining any of the following embodiments and their modifications.

[0010] In the following description of embodiments, configurations may be described using terms with "approximately" attached, such as "approximately parallel" and "approximately orthogonal." For example, "approximately parallel" means not only that they are perfectly parallel, but also that they are substantially parallel, that is, that is, they are deviated from a perfectly parallel state by, for example, a few percent. The same applies to other terms with "approximately." Also, each figure is a schematic diagram and is not necessarily a strictly accurate representation. The scale of the drawings is exaggerated to make the technical features easier to understand. Therefore, it should be noted that the scale of the drawings and the scale of the actual device are not necessarily the same.

[0011] Unless otherwise specified, in drawings, "up" means the upper direction or upper side in the drawing, "down" means the lower direction or lower side in the drawing, "left" means the left direction or left side in the drawing, and "right" means the right direction or right side in the drawing. In addition, in drawings, the same or equivalent elements or components are denoted by the same reference numeral, and redundant explanations are omitted.

[0012] The embodiments described below represent typical embodiments of the Technology and should not be interpreted as narrowing the scope of the Technology. The effects described herein are illustrative and not limiting, and other effects may also exist.

[0013] The explanation will proceed in the following order: 1. First embodiment of this technology (Example 1 of an optical switch) (1) Overview of silicon photonics technology (2) MZ interferometer (3) Applied voltage waveform (4) Control of optical switch switching (5) Voltage waveform generated by the waveform generation unit 2. Second embodiment of this technology (Example 2 of an optical switch) 3. Third embodiment of this technology (Example 3 of an optical switch) 4. Fourth embodiment of this technology (Example of a distance measuring device) 5. Fifth embodiment of this technology (Example of an electronic device)

[0014] [1. First Embodiment of the Technology (Example 1 of an Optical Switch)] [(1) Overview of Silicon Photonics Technology] Silicon photonics technology is a technology based on optical waveguides with silicon as the core and quartz as the cladding, and is a technology for integrating devices and circuits that use light. This technology uses tiny optical devices as elements and utilizes the CMOS process cultivated in the LSI industry to achieve a high degree of integration between electronic circuits and optical circuits.

[0015] For example, FMCW LiDAR is a distance measuring device that utilizes silicon photonics technology. It measures the distance to an object by irradiating it with laser light and using the reflected light. FMCW LiDAR uses, for example, a Mach-Zehnder interferometer (MZ interferometer) or a slow-light deflector to perform highly accurate distance measurements by scanning the direction of the laser beam in two dimensions. This scanning technology makes it possible to emit and receive light from various angles, enabling distance measurements over a wide range.

[0016] [(2) MZ Interferometer] The MZ interferometer is a technology that allows for the selection of an output destination according to the input by interfering light through two optical paths. For example, by heating one of the two paths, the refractive index of the waveguide changes, which creates a phase difference and alters the interference of the light. This mechanism makes it possible to dynamically select the output destination of the light.

[0017] An example of an MZ interferometer configuration will be explained with reference to Figure 1. Figure 1 is a schematic perspective view showing an example of an MZ interferometer configuration.

[0018] As shown in Figure 1, the MZ interferometer 1 is a device that controls interference by splitting light into two different paths and switching the path of an optical signal.

[0019] In this configuration, light enters through the waveguide 11 and branches into two paths at the branching point. Heaters 12 are placed along each path. When a voltage is applied to each heater 12 via the electrode 13, the temperature of the heaters 12 increases. As the temperature of the heaters 12 increases, the temperature of the waveguide 11 changes, which in turn changes the refractive index of the waveguide 11. This change in refractive index causes a change in the phase of the light, and interference occurs when the paths rejoin.

[0020] The MZ interferometer 1 has two output ports: a cross port and a bar port. Interference determines which port the light is output from. The cross port is the path through which the input light is output in the opposite direction to its straight-line direction due to interference, while the bar port is the path through which the light is output in a straight line.

[0021] By controlling the voltage applied to the heater 12, the phase difference is appropriately adjusted, allowing the light output destination to be selected as either the cross port or the bar port. For example, when the heater 12 heats up to an appropriate phase difference, the light is output from the cross port due to light interference. On the other hand, when a different phase difference occurs, the light is output from the bar port. In this way, the MZ interferometer 1 can be used as an optical switch to switch the path of the optical signal.

[0022] The heater 12 may contain, for example, TiN (titanium nitride). TiN has excellent wear resistance and corrosion resistance, as well as excellent electrical and thermal properties, making it suitable as a material for the heater 12 in devices such as optical waveguides. In particular, it is easy to thin and is suitable for the integration of optical devices.

[0023] Furthermore, the heater 12 may also contain Pt (platinum). Pt is suitable as a material for the heater 12 because it has extremely good electrical conductivity and high heat resistance, as well as excellent oxidation resistance. In particular, it is suitable as a material for the heater 12 of an optical device because it exhibits stable properties with respect to temperature changes.

[0024] Further, the heater 12 may contain NiCr (nickel-chromium alloy). NiCr has a high resistivity and oxidation resistance and is suitable as a material for the heater 12. In particular, since NiCr operates stably even in a high-temperature environment, it is suitable for temperature control of silicon photonics devices.

[0025] The MZ interferometer 1 is used as an optical switch or optical modulator in an optical communication system and can be utilized particularly in scenarios where high-speed and high-precision optical control is required. Also, since the phase control technology utilizing the thermo-optical effect enables dynamic control of the optical signal path, it can also play an important role in the fields of LiDAR (light detection and ranging) and optical networks.

[0026] [(3) Applied voltage waveform] In the prior art, when the applied voltage of the heater was switched, the temperature changed gradually, and it took a long time for the temperature of the waveguide to stabilize. This will be described while referring to FIG. 2. FIG. 2A is a graph showing the applied voltage waveform to the heater according to an embodiment of the present technology. FIG. 2B is a graph showing the time change of the temperature of the waveguide.

[0027] In the graph shown in FIG. 2A, the vertical axis represents the heater power P (the power supplied to the heater by applying a voltage to the heater), and the horizontal axis represents the time t. The dotted line shows the power waveform in the prior art, and the dashed line and solid line show the power waveforms in the present technology.

[0028] In the graph shown in FIG. 2B, the vertical axis represents the temperature of the waveguide, and the horizontal axis represents the time t. The dotted line, dashed line, and solid line respectively correspond to FIG. 2A.

[0029] In FIG. 2A, the dotted line shows the case where the heater power is simply switched from the initial power P1 to the target heater power P2. As shown by the dotted line in FIG. 2B, when transitioning from the initial power P1 to the target power P2, the temperature changes slowly, tracing a gentle curve from the initial temperature T1 to the target temperature T2.

[0030] This delay has limited the performance improvement in systems that require high-speed operation, such as FMCW LiDAR. During the switch from the initial temperature T1 to the target temperature T2, the light output was dispersed to both the cross port and the bar port, making it difficult for the light to take the optimal path. Therefore, a method for quickly switching the temperature has been demanded.

[0031] In this technology, an "inverse sawtooth waveform" is adopted as the waveform of the applied voltage. As shown by the solid line in Fig. 2A, the inverse sawtooth waveform is such that the voltage applied to the heater changes from the initial voltage (initial power P1) to the limit voltage (limit power P Max ) in the shortest possible time (instantaneously), and then changes from the limit voltage (limit power P Max ) to the target voltage (target power P2). By changing the applied voltage in this way, as shown by the solid line in Fig. 2B, it becomes possible to rapidly increase the temperature of the waveguide from the initial temperature T1 to the target temperature T2 and stabilize it in a short time.

[0032] When the target power P2 is higher than the initial power P1, the limit voltage (limit power) is the maximum voltage (maximum power P Max ) that is higher than the target voltage (target power P2). On the other hand, when the target power P2 is lower than the initial power P1, the limit voltage (limit power) is the minimum voltage (minimum power P Min ) that is lower than the target voltage (target power P2).

[0033] By controlling the voltage waveform in this way, the delay in temperature change in the prior art is eliminated, and in a system that requires a high-speed response such as FMCW LiDAR, the temperature switching time can be shortened to the order of several microseconds, realizing an improvement in the frame rate.

[0034] Also, as shown by the solid line in Fig. 2B, according to this technology, the overshoot and undershoot when reaching the target temperature T2 are suppressed. Therefore, it is difficult for an error to occur until it stabilizes at the target temperature T2. By minimizing the sudden overshoot and undershoot of the temperature, it is possible to prevent the light output from becoming unstable between the cross port and the bar port. Therefore, this technology can achieve high-speed and high-precision optical switching compared with the prior art.

[0035] In Figure 2A, the dashed line shows a rectangular waveform. The rectangular waveform represents the transition from initial power P1 to limiting power P MAX This method involves instantaneously switching the voltage. Similar to the solid line in Figure 2B, this method can rapidly raise the waveguide temperature from the initial temperature T1 to the target temperature T2. However, compared to the inverse sawtooth waveform, the rectangular waveform is more prone to upward and downward fluctuations, making it more susceptible to errors before stabilizing at the target temperature T2.

[0036] Based on the above, this technology provides an optical switch that changes the phase of light based on the thermo-optic effect, comprising a heater that changes the temperature of a region where the refractive index changes due to the thermo-optic effect, and a waveform generation unit (described later) that generates a voltage waveform that controls the time change of the voltage applied to the heater, wherein the waveform generation unit changes the voltage from an initial voltage P1 to a limit voltage (maximum or minimum voltage) in the shortest possible time, and then changes the voltage from the limit voltage to a target voltage P2.

[0037] An optical switch according to one embodiment of this technology may include a Mach-Zehnder interferometer (MZ interferometer) that changes the phase of light based on the thermo-optic effect. An example of the configuration of the MZ interferometer has been explained with reference to Figure 1, so a further explanation will be omitted.

[0038] Furthermore, the device included in the optical switch is not limited to an MZ interferometer, as it only needs to be able to change the phase of light based on the thermo-optic effect. An optical switch according to one embodiment of this technology may include, for example, a ring resonator. A ring resonator is an optical device that has a structure that resonates light in a ring-shaped waveguide and provides various optical functions such as filtering of optical signals, optical switching, and phase shifting. The ring resonator can adjust the path and phase of light by controlling the resonance conditions of light in the waveguide with temperature and voltage.

[0039] In a ring resonator, light circulates repeatedly through a ring-shaped waveguide, causing specific wavelengths of light to resonate strongly. This resonance state can be controlled by changing the waveguide temperature based on thermo-optic effects, which alters the refractive index within the ring and adjusts the phase. Specifically, the temperature can be changed by heaters placed in the waveguide, thereby controlling the wavelength selectivity and path selectivity of the light.

[0040] Because ring resonators have high frequency selectivity, they can also function as optical filters, resonating only with light of specific wavelengths. This property makes them applicable to optical communications and optical networks for extracting specific signals or removing unwanted wavelengths.

[0041] Furthermore, ring resonators are extremely small and highly efficient devices that can be used in optical integrated circuits. This enables very fast and low-power optical switching and filtering.

[0042] [(4) Control of Optical Switch Switching] Figure 3 is a schematic diagram showing the configuration of a control system for switching an optical switch according to one embodiment of this technology. This system is divided into an SOC region 2 and an optical circuit region 3, which control the voltage application to the heater and the operation of the optical switch, respectively.

[0043] A System on Chip (SOC) is a single integrated circuit that incorporates the functions of an entire system, handling a variety of functions such as generating control signals and adjusting waveforms.

[0044] In the SOC region, the input circuit 22 receives a temperature command signal (High / Low) and transmits it to the waveform generation unit 21. The waveform generation unit 21 consists of a Schmitt trigger and an integrating circuit, and generates a voltage waveform to be applied to the heater. This waveform generation unit 21 generates an inverted sawtooth voltage waveform. This voltage waveform causes the temperature of the heater and waveguide to change rapidly, improving the switching speed of the optical switch.

[0045] The output circuit 23 generates a voltage signal to be supplied to the heater, and this voltage signal is supplied to the optical circuit region 3 as the applied voltage 24.

[0046] The heater status signal (High / Low) plays a role in monitoring the heater status in real time and providing feedback on the control signal. The graph showing the heater status signal illustrates the relationship between the voltage V supplied to the heater and the heater status signal (Low→High and High→Low). The vertical axis represents the voltage V applied to the heater, and the horizontal axis represents the passage of time.

[0047] First, when the heater status signal switches from "Low" to "High," the voltage to the heater increases from a low state (Low) to a high state (High). In this state, the heater receives high power, and the temperature of the waveguide rises rapidly. This changes the refractive index of the waveguide, causing the optical switch to switch.

[0048] Next, when the heater status signal switches from "High" to "Low," the voltage applied to the heater decreases from a high state (High) to a low state (Low). At this time, the power supply to the heater decreases, and the waveguide temperature drops and stabilizes. As a result, the phase control of the optical switch is completed, and the optical signal is output to the desired output port.

[0049] As shown in this graph, the heater voltage takes an inverse sawtooth waveform to control rapid changes in heater power. This control prevents excessive fluctuations in waveguide temperature, enabling stable temperature control in a short time. This voltage control also shortens the switching time of the optical switch, resulting in improved performance in systems requiring fast response.

[0050] In the optical circuit region 3, the path of the optical signal is controlled by a heater located in the optical switch. As shown in the figure, the heater operates in three states: Low 31, switching in progress 32, and High 33, and switches the output of the optical signal to the cross port and bar port.

[0051] Optical switches, when arranged in a tournament tree configuration, can branch incoming light into multiple paths. For example, one input can be used to select two paths, and then two more paths can be selected further down the line. By selecting paths in this stepwise manner, it is possible to control, for example, eight or more output destinations, and to construct complex optical switching networks with any number of branches.

[0052] This switching operation can be performed in a much shorter time compared to conventional technology by using voltage control with an inverse sawtooth waveform. In conventional technology, the switching time of the optical switch was long, affecting the frame rate of FMCW LiDAR and other systems, but in this technology, the optical switch switching time is drastically reduced by precise control of the heater voltage.

[0053] At the bottom of the diagram showing the tournament tree, a comparison of the optical switch switching times in the conventional technology and the present technology is shown. A "frame" is a time-divided unit of the operation in which an optical switch selects from multiple optical paths. Within one frame, the optical switch performs stepwise switching across multiple paths to select the antenna that inputs and outputs the laser light.

[0054] The figure compares the optical switch switching time in the conventional method with that of this technology. In the conventional method, the optical switch switching within a single frame was slow, resulting in a delay in switching the antenna output path and thus a decrease in the overall system response speed. In contrast, in this technology, the optical switch switching time is shortened by optimizing the heater voltage waveform control, enabling rapid optical path selection within a single frame. As a result, an overall improvement in frame rate is achieved, which is advantageous in systems requiring high-speed response.

[0055] This control system optimizes the switching speed of optical switches in optical distance measurement systems such as FMCW LiDAR, improving the frame rate and enabling high-speed and high-precision measurements.

[0056] [(5) Voltage waveform generated by the waveform generation unit] An example of the voltage waveform (power waveform) generated by the waveform generation unit 21 will be described while referring to FIG. 4. FIG. 4 is a graph showing an example of the power waveform supplied to the heater according to an embodiment of the present technology. In this graph, the vertical axis represents the power P [W] supplied to the heater, and the horizontal axis represents the time T [s].

[0057] In the initial state, an initial power P1 is supplied to the heater, and the temperature of the waveguide is maintained in a stable and low state. Thereafter, the power instantaneously rises to the limit power P Max to rapidly increase the temperature. The limit power P Max is higher than the target power P2. Instead of simply switching from the initial power P1 to the target power P2, the power is instantaneously increased to the limit power P Max higher than the target power P2.

[0058] The change in power from the initial power P1 to the limit power P Max is preferably performed instantaneously. More specifically, the shortest possible time required for this power change is preferably 0.01 microseconds or more and 100 microseconds or less.

[0059] Thereafter, the power gradually decreases to the target power P2 according to the reverse sawtooth waveform. In this case, the change in power (voltage) from the limit power (limit voltage) P Max to the target power (target voltage) P2 is linear.

[0060] Here, in order to suppress the overshoot and undershoot when the waveguide of the Mach-Zehnder interferometer reaches the target temperature, it is preferable that the waveform generation unit 21 (see FIG. 3) generates a specific voltage waveform. Specifically, the waveform generation unit 21 integrates the change amount of the thermal energy accumulated in the heater and its vicinity and the power (heater power) P corresponding to the voltage applied to the heater with the transition time t from the initial voltage to the target voltage (the area of the gray shaded region shown in FIG. 4), and it is preferable to control the voltage waveform (power waveform) so that they are equal.

[0061] This can be expressed mathematically. u is the thermal energy stored in the heater and its surrounding region per unit of power, P1 is the power corresponding to the initial voltage, P2 is the power corresponding to the target voltage, and P2 is the power corresponding to the limit voltage (maximum voltage). Max Let t be the transition time from the initial voltage to the target voltage. In this case, it is preferable that the waveform generation unit 21 generates a voltage waveform that satisfies the following equation (1).

[0062]

[0063] When comparing the temperature distribution when power P1 corresponding to the initial voltage is supplied with the temperature distribution when power P2 corresponding to the target voltage is supplied, an energy difference exists between them. Focusing on this energy difference, the inventors conceived the idea that by instantaneously applying thermal energy equivalent to this energy difference when switching from P1 to P2, the waveguide temperature can be stabilized in a short time, preventing upward and downward fluctuations when the target temperature is reached.

[0064] Specifically, by instantaneously supplying power equivalent to this energy difference, temperature fluctuations are minimized, and the desired temperature can be reached in a shorter time compared to conventional gradual temperature changes. This technology significantly improves the responsiveness of the heater and dramatically shortens the time it takes for the waveguide temperature to stabilize. As a result, it suppresses the temperature fluctuations that occur when reaching the target temperature, and the waveguide temperature can quickly reach a predetermined stable state.

[0065] The energy stored in the heater and its vicinity is the thermal energy transferred to the surrounding material due to the heating of the heater. This energy is generated when a voltage is applied to the heater adjacent to the waveguide, and is produced when the waveguide is heated. When observing the device cross-section, the heat generated from the heater forms a temperature distribution that spreads concentrically around the heater. Based on this temperature distribution, the heat capacity of the components at each location and the stored energy due to the temperature rise can be calculated, and based on these results, the amplitude and temporal length of the waveform can be adjusted.

[0066] Specifically, thermal simulations are effective for calculating this energy. For example, by using commercially available thermal simulation tools, the shapes of the waveguide, heater, and surrounding silicon devices are first constructed as 3D models. Then, the relevant boundary conditions are set and the heat conditions applied to the heater are input. Finally, by solving the equations governing heat, the ambient temperature distribution associated with the heating of the heater can be obtained.

[0067] Figure 4 shows the power waveform when the power P2 corresponding to the target voltage is higher than the power P1 corresponding to the initial voltage. On the other hand, the power waveform when the power P2 corresponding to the target voltage is higher than the power P1 corresponding to the initial voltage will be explained with reference to Figure 5. Figure 5 is a graph showing an example of the power waveform supplied to a heater according to one embodiment of this technology. In this graph, the vertical axis represents the power P [W] supplied to the heater, and the horizontal axis represents time T [s].

[0068] In the initial state, the heater is supplied with initial power P1, and the waveguide temperature is maintained at a stable low level. Subsequently, the power is instantaneously reduced to limiting power P Min It descends to a certain point, rapidly lowering the temperature. Limit power P Min The power is lower than the target power P2. Instead of simply switching from the initial power P1 to the target power P2, the limit power P is lower than the target power P2. Min It instantly reduces the power to that level.

[0069] From initial power P1 to limiting power P min The change in power is preferably instantaneous. More specifically, the shortest possible time required for this power change is preferably 0.01 microseconds or more and 100 microseconds or less.

[0070] Subsequently, the power follows an inverse sawtooth waveform, gradually increasing until it reaches the target power P2. In this case, the limiting power (limiting voltage) P Min The change in power (voltage) from the target power (target voltage) P2 is linear.

[0071] Let u be the thermal energy stored in the heater per unit of power, P1 be the power corresponding to the initial voltage, P2 be the power corresponding to the target voltage, and P be the power corresponding to the limit voltage (minimum voltage). Min Let t be the transition time from the initial voltage to the target voltage. In this case, it is preferable that the waveform generation unit 21 generates a voltage waveform that satisfies the following equation (2).

[0072]

[0073] Incidentally, in Figures 4 and 5, the voltage change from the limit voltage to the target voltage is shown as linear, but it does not necessarily have to be linear. The voltage change from the limit voltage to the target voltage may be nonlinear. In particular, by further optimizing the shape of the applied voltage waveform, it becomes possible to stabilize the temperature change of the waveguide in a shorter time.

[0074] Specifically, with linear voltage changes, temperature fluctuations are relatively gradual, which can limit the response speed. On the other hand, by employing a nonlinear voltage change curve, it becomes possible to achieve a faster transient response in temperature control by the heater. This is expected to reduce the time it takes to reach the target temperature while suppressing rapid temperature fluctuations. For example, by designing a curve that rapidly increases the voltage in the initial stage and then transitions to a gradual change, it is possible to suppress upward and downward temperature fluctuations and achieve faster and more stable temperature control. Such control is particularly effective in systems and devices that require high-speed response.

[0075] This technology is applicable to silicon photonics technology in general. In silicon photonics technology, optical integrated circuits can be constructed based on optical waveguides with a silicon core and quartz cladding. This technology utilizes the CMOS process cultivated in LSI manufacturing and highly integrates electronic and optical circuits. By applying this technology, for example, high-speed processing of optical signals becomes possible in optical communication systems, and distance measurement can be performed with high accuracy and speed in LiDAR (light detection and ranging) technology.

[0076] The above description of the optical switch according to the first embodiment of this technology can be applied to other embodiments of this technology, unless there are any particular technical inconsistencies.

[0077] [2. Second Embodiment of the Technology (Example 2 of Optical Switches)] As shown in Figure 4, the amplitude (P) is obtained from the power waveform (voltage waveform). Max -P2) and the length of time (transition time t from initial voltage to target voltage) are determined. Regarding the relationship between the length of time and amplitude of the power waveform, the shorter the length of time, the larger the amplitude, and the longer the length of time, the smaller the amplitude.

[0078] However, shortening the time interval t too much causes an excessive upward fluctuation in the heater temperature. Therefore, it is difficult to arbitrarily shorten the time interval t.

[0079] Therefore, it is necessary to appropriately adjust the time length t to suppress both upward and downward deviations. It is recommended to use thermal simulation or calculation formulas for this adjustment. An example of a calculation formula is to derive the transient temperature response using a thermal RC ladder circuit.

[0080] Furthermore, there are limitations on the amplitude of the power waveform. The amplitude limit is defined based on the following conditions: When lowering the temperature, the amplitude limit corresponds to 0W (zero watts). This value indicates the lower limit beyond which the heater's heat output cannot be reduced. On the other hand, when raising the temperature, the amplitude is determined by the maximum wattage that can be supplied to the heater, which is predetermined based on past evaluation results, etc.

[0081] The heater powers P1 and P2 under stable temperature conditions require individual device adjustments to account for manufacturing variations in the waveguide. These adjustments are determined by monitoring the extinction ratio during the testing phase.

[0082] Furthermore, P1 and P2 represent the 100% state of the cross port and the 100% state of the bar port, respectively, but due to manufacturing variations, adjustments are necessary for each individual device. Therefore, it is difficult to determine the specific wattage values ​​of P1 and P2 at the design stage.

[0083] Therefore, it is preferable that the heater power values ​​P1 and P2 when the temperature is stable be automatically optimized during the pre-shipment testing phase to compensate for individual differences due to manufacturing variations. This optimization process is carried out, for example, by detecting the light emitted from the optical switch and feeding the detection result back to the waveform generation unit. This adjusts the heater power so that the light intensity is maximized.

[0084] An example of the configuration of an optical switch according to one embodiment of this technology will be described with reference to Figures 6 to 8. Figures 6 to 8 are block diagrams showing an example of the configuration of an optical switch according to one embodiment of this technology.

[0085] As shown in Figures 6 to 8, the optical switch 100 according to one embodiment of this technology may further include a power correction unit 25 that corrects the power corresponding to the initial voltage and the power corresponding to the target voltage. This power correction unit 25 can be realized by using, for example, a photodiode (PD).

[0086] The power correction unit 25 detects the amount of light based on the phase change of light and feeds the detection result back to the waveform generation unit 21, thereby correcting the power corresponding to the initial voltage and the power corresponding to the target voltage. This makes it possible to correct individual differences due to manufacturing variations.

[0087] As shown in Figure 6, the power correction unit 25 may be connected between the device that changes the phase of light (e.g., an MZ interferometer) 1 and the optical antenna (transmitting antenna 26). The power correction unit 25 can correct the power corresponding to the initial voltage and the power corresponding to the target voltage by detecting the output light amount of the device 1 and feeding the detection result back to the waveform generation unit 21.

[0088] Alternatively, as shown in Figure 7, the power correction unit 25 may be connected to an optical antenna (transmitting antenna 26) connected to a device 1 that changes the phase of light. The power correction unit 25 can correct the power corresponding to the initial voltage and the power corresponding to the target voltage by detecting the amount of light emitted from the optical antenna (transmitting antenna 26) and feeding back the detection result to the waveform generation unit 21.

[0089] Alternatively, as shown in Figure 8, the power correction unit 25 may be connected to an optical antenna (receiving antenna 27) connected to a device 1 that changes the phase of light. This receiving antenna 27 receives light that has been reflected by an object from the light transmitted from the transmitting antenna 26 (see Figure 7). The power correction unit 25 detects the amount of light received by the receiving antenna 27 and feeds the detection result back to the waveform generation unit 21, thereby correcting the power corresponding to the initial voltage and the power corresponding to the target voltage.

[0090] During this optimization process, the relationship between the heater power of device 1 and the light intensity detected by the power correction unit 25 periodically increases and decreases. This will be explained with reference to Figure 9. Figure 9 is a graph showing the relationship between heater power and light intensity in an optical switch according to one embodiment of this technology. In Figure 9, the horizontal axis represents the heater power P, and the vertical axis represents the light intensity L detected by the power correction unit 25.

[0091] First, the curve shown in Figure 9A illustrates how the light intensity L increases or decreases as the heater power P increases. As the power P increases, the light intensity L increases, and once it reaches a peak (maximum value), it begins to decrease. This maximum value P A1 However, this is the optimal value for heater power.

[0092] The curve shown in Figure 9B similarly illustrates the increase or decrease in light intensity L in response to changes in heater power P. Due to manufacturing variations and individual device differences, the curve shown in Figure 9B is shifted horizontally compared to the curve shown in Figure 9A. For the device shown in Figure 9B, the optimal value of heater power is P B1 Therefore, the heater power required to achieve maximum light output varies depending on the individual device. For this reason, it is necessary to automatically adjust the heater power during the testing phase and perform automatic optimization to obtain the optimal light output.

[0093] A series of steps for optimizing the power applied to the heater will be described with reference to Figure 10. Figure 10 is a flowchart showing an example of the processing flow of a power correction unit according to one embodiment of this technology. Figure 10 illustrates a method for achieving optimal operation of the optical switch by optimizing the power supplied to the heater by the power correction unit 25.

[0094] First, in step S101, the heater power is set to zero.

[0095] Next, in step S102, the "maximum light intensity" is initialized to the light intensity when the heater power is zero.

[0096] Next, in step S103, the "maximum light intensity update flag" is initialized to the off state.

[0097] Next, in step S104, the heater power is increased.

[0098] Next, when the amount of light detected by the power correction unit 25 is equal to or greater than the "maximum light amount" (step S105: Yes), in step S106, the "maximum light amount" is updated, and the heater power in this case (P in Figure 9) A2 , P B2 ) is recorded. Then, in step S107, the "maximum light intensity update flag" is turned on, and then in step S104, the heater power is further increased.

[0099] On the other hand, when the amount of light detected by the power correction unit 25 is less than the "maximum light intensity" (step S105: No), in step S108, the state of the "maximum light intensity update flag" is determined. When the "maximum light intensity update flag" is in the ON state (step S108: Yes), in step S109, the heater power at the "maximum light intensity" recorded in step S106 is set to the optimal value. When the "maximum light intensity update flag" is in the OFF state (step S108: No), in step S104, the heater power is further increased.

[0100] This process automatically adjusts the heater power to account for manufacturing variations and individual differences, resulting in optimal light output.

[0101] The above description of the optical switch according to the second embodiment of this technology can be applied to other embodiments of this technology, unless there are any particular technical inconsistencies.

[0102] [3. Third Embodiment of the Technology (Example 3 of Optical Switches)] The voltage waveform applied to the heater is adjusted using thermal simulation and calculation formulas to suppress temperature fluctuations.

[0103] On the other hand, it is also possible to optimize the voltage waveform during the pre-shipment testing phase without performing thermal simulations or similar procedures.

[0104] An example of the configuration of an optical switch according to one embodiment of this technology will be described with reference to Figures 11 to 13. Figures 11 to 13 are block diagrams showing an example of the configuration of an optical switch according to one embodiment of this technology.

[0105] As shown in Figures 11 to 13, the optical switch 100 according to one embodiment of this technology may further include an amplitude determination unit 28 that determines the amplitude of the voltage waveform applied to the heater (see Figures 4 and 5). This amplitude determination unit 28 can be realized, for example, by using a photodiode (PD).

[0106] The amplitude determination unit 28 gradually changes the amplitude so that the transition time from the initial voltage to the target voltage is minimized, thereby determining the optimal amplitude. This makes it possible to suppress temperature fluctuations both upward and downward.

[0107] As shown in Figure 11, the amplitude determination unit 28 may be connected between the device 1 that changes the phase of light (for example, an MZ interferometer) and the optical antenna (transmitting antenna 26). The amplitude determination unit 28 can determine the optimal amplitude by detecting the output light amount of the device 1 and feeding the detection result back to the waveform generation unit 21.

[0108] Alternatively, as shown in Figure 12, the amplitude determination unit 28 may be connected to an optical antenna (transmitting antenna 26) connected to a device 1 that changes the phase of light. The amplitude determination unit 28 can determine the optimal amplitude by detecting the amount of light emitted from the optical antenna (transmitting antenna 26) and feeding the detection result back to the waveform generation unit 21.

[0109] Alternatively, as shown in Figure 13, the amplitude determination unit 28 may be connected to an optical antenna (receiving antenna 27) connected to a device 1 that changes the phase of light. This receiving antenna 27 receives light that has been reflected by an object from the light transmitted from the transmitting antenna 26 (see Figure 12). The amplitude determination unit 28 can determine the optimal amplitude by detecting the amount of light received by the receiving antenna 27 and feeding the detection result back to the waveform generation unit 21.

[0110] A series of steps for optimizing the voltage waveform will be described with reference to Figure 14. Figure 14 is a flowchart showing an example of the processing flow of the amplitude determination unit according to one embodiment of this technology. Figure 14 illustrates a method for achieving optimal operation of the optical switch by optimizing the voltage waveform in the amplitude determination unit 28.

[0111] The processing flow outlines the following: it begins with a sharp, inverted sawtooth waveform, then, while keeping the area (the shaded area in Figures 4 and 5) constant, the amplitude is gradually reduced while the length of the voltage waveform (see Figures 4 and 5) is gradually increased. Finally, the optimal amplitude and length are determined.

[0112] Hereafter, the transition time from the initial voltage to the target voltage will be defined as the stabilization time, meaning the time required for the temperature to stabilize.

[0113] It should be assumed that the heater powers P1 and P2 at temperature stabilization are already optimized before the amplitude determination unit 28 determines the optimal amplitude. Since the light intensity at stabilization is also determined during the test phase, it is possible to automatically adjust the amplitude and length of the voltage waveform applied to the heater based on the detected light intensity.

[0114] First, in step S201, the amplitude of the voltage waveform is set to the upper limit.

[0115] Next, in step S202, the length of the voltage waveform is calculated based on the area of ​​the voltage waveform (the shaded area in Figures 4 and 5) and the amplitude.

[0116] Next, in step S203, a voltage waveform is applied to switch from the steady state of heater power P1 corresponding to the initial voltage to the steady state of heater power P2 corresponding to the target voltage.

[0117] Next, in step S204, the stabilization time from the initial voltage to the target voltage is set to the initial value of the "minimum stabilization time".

[0118] Next, in step S205, after sufficient time has passed, the heater power is returned from the steady state of P2 to the steady state of P1.

[0119] Next, in step S206, the amplitude is reduced.

[0120] Next, in step S207, the length of the voltage waveform is calculated based on the area and amplitude of the voltage waveform.

[0121] Next, in step S208, a voltage waveform is applied to switch from the steady state of heater power P1 corresponding to the initial voltage to the steady state of heater power P2 corresponding to the target voltage.

[0122] If the stabilization time from the steady state of heater power P1 to the steady state of heater power P2 is less than or equal to the "minimum stabilization time" (step S209: Yes), then in step S211, the "minimum stabilization time" is updated and the amplitude and length in this case are recorded. Then, the processing from step S205 onwards is executed.

[0123] On the other hand, when the stabilization time from the steady state of heater power P1 to the steady state of heater power P2 is greater than the "minimum stabilization time" (step S209: No), in step S210, the amplitude and length of the "minimum stabilization time" recorded in step S211 are set to the optimal values.

[0124] The processing of the amplitude determination unit 28 will be further explained with reference to Figure 15. Figure 15 is a graph showing an example of the processing of the amplitude determination unit according to one embodiment of this technology. Figure 15 shows the process of determining the optimal voltage waveform based on the amount of light detected by the amplitude determination unit 28 while adjusting the heater power. The horizontal axis represents the amplitude A of the voltage waveform, and the vertical axis represents the stabilization time T until switching from the steady state of heater power P1 to the steady state of heater power P2.

[0125] Figure 15A shows the upper limit of amplitude A. Max This is the case when the optimal value is OV. The amplitude A is gradually decreased, and the optimal value of amplitude A is determined when the stabilization time T becomes greater than the "minimum stabilization time".

[0126] Figure 15B shows the upper limit of amplitude A. Max This is the case when the amplitude A is not the optimal value OV. In this case as well, the amplitude A is gradually decreased, and the optimal value of amplitude A is determined when the stabilization time T becomes greater than the "minimum stabilization time".

[0127] Through the above process, the applied voltage waveform is automatically optimized to minimize the temperature stabilization time. This stabilization time is defined as the time during which the amount of light detected by the amplitude determination unit 28 remains within the allowable range based on the device specifications. The allowable range is determined based on the device characteristics and operating conditions. Through this automatic optimization process, the transient temperature response is efficiently controlled, and the optical switch operates quickly and stably.

[0128] The cases where the amplitude is at its optimal value and where it is not will be explained with reference to Figure 16. Figure 16 is a graph showing the characteristics of the optical switch. The horizontal axis represents time T, and the vertical axis represents the amount of light L detected by the amplitude determination unit 28.

[0129] The gray-shaded band in the diagram represents the tolerance range, which is determined based on the characteristics and operating conditions of the optical switch. The heater control aims to rapidly switch and stabilize the temperature within this tolerance range, and the diagram illustrates the temperature response process in this manner.

[0130] Figure 16A shows the case where the amplitude of the voltage waveform is too large. In this case, the light intensity initially rises sharply, then experiences a large downward fluctuation, and finally stabilizes within the acceptable range. The stabilization time in this case is T. A Therefore, during downward fluctuations, it temporarily falls outside the acceptable range.

[0131] On the other hand, Figure 16B shows the case where the amplitude of the voltage waveform is appropriate. The light intensity increases rapidly, then settles within the acceptable range, albeit with a downward fluctuation, and the stabilization time is T B This is the result. Stabilization time T B This is the stabilization time T shown in Figure 16A. A It is shorter than that.

[0132] As a result, the shape (amplitude and duration) of the voltage waveform applied to the heater is automatically adjusted based on the light intensity monitoring by the amplitude determination unit 28. This enables rapid temperature stabilization and improves the operating performance of the optical switch.

[0133] The above description of the optical switch according to the third embodiment of this technology can be applied to other embodiments of this technology, unless there are any particular technical inconsistencies.

[0134] [4. Fourth Embodiment of the Technology (Example of a Distance Measuring Device)] The technology provides a distance measuring device that includes an optical switch that changes the phase of light based on the thermo-optic effect, wherein the optical switch includes a heater that changes the temperature of a region in which the refractive index changes due to the thermo-optic effect, and a waveform generation unit that generates a voltage waveform that controls the time change of the voltage applied to the heater, wherein the waveform generation unit changes the voltage from an initial voltage to a limit voltage in the shortest possible time, and then changes the voltage from the limit voltage to a target voltage.

[0135] In other words, this technology provides a distance measuring device equipped with an optical switch according to any one of the first to third embodiments.

[0136] An example of the configuration of the range measuring device according to this embodiment will be described with reference to Figure 17. Figure 17 is a block diagram showing an example of the configuration of a range measuring device according to one embodiment of this technology. This figure shows an example of the configuration of an optical integrated circuit type LiDAR, which is an example of a range measuring device. The optical integrated circuit type LiDAR provides a coherent optical radar device suitable for long and medium-range range measuring using silicon photonics technology.

[0137] As shown in Figure 17, the distance measuring device 1000 consists of the following main elements.

[0138] The light source 101 is a light source that generates continuous light used for distance measurement. This light source 101 continuously emits laser light at a constant wavelength.

[0139] The frequency modulator 102 is a device that adds frequency modulation from the signal modulation source 103 to the continuous light output from the light source 101. The modulated light is transmitted toward the object 200 and used for distance measurement.

[0140] The collimating lens 104 is an optical element for converting laser light into parallel light. By ensuring that the irradiated light travels in a straight line towards the target without spreading out, measurement accuracy is improved.

[0141] The slow light deflector 105 is a device that achieves more accurate distance measurement by controlling the direction of light propagation and delaying the phase of the optical signal.

[0142] The optical switch 100 is an optical switch according to any one of the first to third embodiments, and performs branching and switching of optical signals.

[0143] The silicon photonics circuit 106 is a circuit that utilizes silicon photonics technology and performs high-speed processing and transmission of optical signals. Silicon photonics enables the integration of optical and electronic circuits, contributing to the miniaturization and performance improvement of the distance measuring device 1000.

[0144] The photodetector 107 is a photodetector that receives reflected light and converts it into an electrical signal. For example, a detector using Ge (germanium) is highly sensitive and improves the accuracy of distance measurement.

[0145] The signal processing circuit 108 is a circuit that processes the received optical signal and calculates the distance to the object 200. This circuit filters and digitizes the received signal to generate measurement data.

[0146] The control circuit 109 is responsible for controlling the entire distance measuring device 1000, and controls the operation of each device, such as the light source 101, frequency modulator 102, and optical switch 100. This optimizes the timing control and signal processing of the distance measuring device 1000.

[0147] In this range measuring device 1000, laser light emitted from the light source 101 is modulated by the frequency modulator 102 and irradiated onto the object 200 via the collimating lens 104. The light reflected from the object 200 is detected by the photodetector 107 and analyzed through the signal processing circuit 108. This signal analysis calculates the distance and velocity to the object 200.

[0148] Furthermore, by using the slow light deflector 105 and the optical switch 100, the phase and direction of the optical signal can be precisely controlled, enabling accurate distance measurement for a wide range of objects. This achieves high-precision distance measurement at long and medium distances.

[0149] This technology enables the rangefinder 1000 to achieve high sensitivity and high-speed measurement, and the application of silicon photonics technology allows for both miniaturization and high performance. As a result, the accuracy and efficiency of the optical radar are greatly improved.

[0150] The above description of the distance measuring device according to the fourth embodiment of this technology can be applied to other embodiments of this technology unless there are any particular technical inconsistencies.

[0151] [5. Fifth Embodiment of the Technology (Example of an Electronic Device)] The technology provides an electronic device that includes an optical switch that changes the phase of light based on the thermo-optic effect, wherein the optical switch includes a heater that changes the temperature of a region in which the refractive index changes due to the thermo-optic effect, and a waveform generation unit that generates a voltage waveform that controls the time change of the voltage applied to the heater, wherein the waveform generation unit changes the voltage from an initial voltage to a limit voltage in the shortest possible time, and then changes the voltage from the limit voltage to a target voltage.

[0152] In other words, this technology provides an electronic device equipped with an optical switch according to any one of the first to third embodiments.

[0153] This technology can be applied to a variety of products. For example, it may be implemented as a device mounted on any type of mobile vehicle, such as automobiles, electric vehicles, hybrid electric vehicles, motorcycles, bicycles, personal mobility devices, airplanes, drones, ships, or robots.

[0154] Figure 18 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile control system to which the technology described herein may be applied.

[0155] The vehicle control system 12000 comprises a plurality of electronic control units connected via a communication network 12001. In the example shown in Figure 18, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an external information detection unit 12030, an internal information detection unit 12040, and an integrated control unit 12050. The functional configuration of the integrated control unit 12050 is shown in the figure, which includes a microcomputer 12051, an audio / image output unit 12052, and an in-vehicle network interface 12053.

[0156] The drivetrain control unit 12010 controls the operation of devices related to the vehicle's drivetrain according to various programs. For example, the drivetrain control unit 12010 functions as a control device for a drivetrain generating device that generates driving force for the vehicle, such as an internal combustion engine or a drive motor; a drivetrain transmission mechanism that transmits driving force to the wheels; a steering mechanism that adjusts the steering angle of the vehicle; and a braking device that generates braking force for the vehicle.

[0157] The body system control unit 12020 controls the operation of various devices mounted on the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for a keyless entry system, a smart key system, a power window system, or various lamps such as headlights, reverse lights, brake lights, turn signals, or fog lights. In this case, the body system control unit 12020 may receive radio waves transmitted from a portable device that replaces a key or signals from various switches. The body system control unit 12020 receives these radio waves or signals and controls the vehicle's door lock system, power window system, lamps, etc.

[0158] The external information detection unit 12030 detects information from outside the vehicle equipped with the vehicle control system 12000. For example, an imaging unit 12031 is connected to the external information detection unit 12030. The external information detection unit 12030 causes the imaging unit 12031 to capture images of the outside of the vehicle and receives the captured images. Based on the received images, the external information detection unit 12030 may perform object detection processing such as detecting people, cars, obstacles, signs, or characters on the road surface, or distance detection processing.

[0159] The imaging unit 12031 is a light sensor that receives light and outputs an electrical signal corresponding to the amount of light received. The imaging unit 12031 can output the electrical signal as an image or as distance measurement information. The light received by the imaging unit 12031 may be visible light or invisible light such as infrared light.

[0160] The in-vehicle information detection unit 12040 detects information inside the vehicle. The in-vehicle information detection unit 12040 is connected to, for example, a driver status detection unit 12041 that detects the driver's state. The driver status detection unit 12041 includes, for example, a camera that captures images of the driver, and the in-vehicle information detection unit 12040 may calculate the driver's level of fatigue or concentration, or determine whether the driver is drowsy, based on the detection information input from the driver status detection unit 12041.

[0161] The microcomputer 12051 can calculate control target values ​​for the drive force generator, steering mechanism, or braking device based on information inside and outside the vehicle acquired by the external information detection unit 12030 or the internal information detection unit 12040, and output control commands to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing ADAS (Advanced Driver Assistance System) functions, including collision avoidance or impact mitigation, following driving based on distance between vehicles, maintaining vehicle speed, vehicle collision warning, or vehicle lane departure warning.

[0162] Furthermore, the microcomputer 12051 can perform cooperative control for purposes such as autonomous driving, where the vehicle drives autonomously without driver intervention, by controlling the drive force generating device, steering mechanism, or braking device, etc., based on information about the vehicle's surroundings acquired by the external information detection unit 12030 or the internal information detection unit 12040.

[0163] Furthermore, the microcomputer 12051 can output control commands to the body system control unit 12020 based on external information acquired by the external information detection unit 12030. For example, the microcomputer 12051 can control the headlights according to the position of a preceding or oncoming vehicle detected by the external information detection unit 12030, and perform coordinated control aimed at reducing glare, such as switching from high beams to low beams.

[0164] The audio-image output unit 12052 transmits at least one of audio and image output signals to an output device capable of visually or audibly notifying information to the vehicle's occupants or to those outside the vehicle. In the example shown in Figure 18, the output devices include an audio speaker 12061, a display unit 12062, and an instrument panel 12063. The display unit 12062 may include, for example, at least one of an onboard display and a head-up display.

[0165] Figure 19 shows an example of the installation position of the imaging unit 12031.

[0166] In Figure 19, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104, and 12105.

[0167] The imaging units 12101, 12102, 12103, 12104, and 12105 are installed, for example, on the front nose, side mirrors, rear bumper, back door, and the upper part of the windshield inside the vehicle 12100. The imaging unit 12101 installed on the front nose and the imaging unit 12105 installed on the upper part of the windshield inside the vehicle mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 installed on the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 installed on the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The imaging unit 12105 installed on the upper part of the windshield inside the vehicle is mainly used for detecting preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, or lanes.

[0168] Figure 19 shows an example of the imaging range of imaging units 12101 to 12104. Imaging range 12111 indicates the imaging range of imaging unit 12101 located on the front nose, imaging ranges 12112 and 12113 indicate the imaging ranges of imaging units 12102 and 12103 located on the side mirrors, respectively, and imaging range 12114 indicates the imaging range of imaging unit 12104 located on the rear bumper or back door. For example, by superimposing the image data captured by imaging units 12101 to 12104, an overhead view image of the vehicle 12100 can be obtained.

[0169] At least one of the imaging units 12101 to 12104 may have a function for acquiring distance information. For example, at least one of the imaging units 12101 to 12104 may be a stereo camera consisting of multiple image sensors, or an image sensor having pixels for phase difference detection.

[0170] For example, the microcomputer 12051, based on distance information obtained from the imaging units 12101 to 12104, can determine the distance to each object within the imaging range 12111 to 12114 and the temporal change of this distance (relative speed to the vehicle 12100). In particular, it can extract the closest object on the vehicle 12100's path that is traveling in approximately the same direction as the vehicle 12100 at a predetermined speed (e.g., 0 km / h or more) as the preceding vehicle. Furthermore, the microcomputer 12051 can set a predetermined distance to be maintained before the preceding vehicle and perform automatic braking control (including follow-and-stop control) and automatic acceleration control (including follow-and-start control), etc. In this way, cooperative control aimed at autonomous driving, where the vehicle drives autonomously without driver intervention, can be performed.

[0171] For example, the microcomputer 12051 can use distance information obtained from imaging units 12101 to 12104 to classify and extract three-dimensional object data related to three-dimensional objects, such as motorcycles, passenger cars, large vehicles, pedestrians, utility poles, and other three-dimensional objects, and use this data for automatic obstacle avoidance. For example, the microcomputer 12051 identifies obstacles around the vehicle 12100 into obstacles that are visible to the driver of the vehicle 12100 and obstacles that are difficult to see. The microcomputer 12051 then determines the collision risk, which indicates the degree of risk of collision with each obstacle. If the collision risk is above a set value and there is a possibility of collision, the microcomputer 12051 can provide driving assistance to avoid collisions by outputting a warning to the driver via the audio speaker 12061 or the display unit 12062, or by performing forced deceleration or evasive steering via the drive system control unit 12010.

[0172] At least one of the imaging units 12101 to 12104 may be an infrared camera that detects infrared light. For example, the microcomputer 12051 can recognize pedestrians by determining whether or not pedestrians are present in the images captured by the imaging units 12101 to 12104. Such pedestrian recognition is performed, for example, by a procedure to extract feature points from the images captured by the imaging units 12101 to 12104 as infrared cameras, and a procedure to perform pattern matching on a series of feature points that indicate the contour of an object to determine whether or not it is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the images captured by the imaging units 12101 to 12104 and recognizes a pedestrian, the audio-image output unit 12052 controls the display unit 12062 to superimpose a rectangular contour line for emphasis on the recognized pedestrian. The audio-image output unit 12052 may also control the display unit 12062 to display an icon indicating a pedestrian at a desired position.

[0173] The above describes an example of a vehicle control system to which this technology may be applied. This technology can be applied to, for example, the imaging unit 12031 in the configuration described above.

[0174] The specific numerical values, shapes, materials (including composition), etc., described herein are examples only and are not limited to these.

[0175] Furthermore, this technology can also take the following configurations: [1] An optical switch that changes the phase of light based on the thermo-optic effect, comprising: a heater that changes the temperature of a region in which the refractive index changes due to the thermo-optic effect; and a waveform generation unit that generates a voltage waveform that controls the time change of the voltage applied to the heater, wherein the waveform generation unit changes the voltage from an initial voltage to a limit voltage (maximum or minimum voltage) in the shortest possible time, and then changes the voltage from the limit voltage to a target voltage. [2] The optical switch according to [1], wherein the shortest possible time is 0.01 microseconds or more and 100 microseconds or less. [3] The optical switch according to [1] or [2], wherein the change in voltage from the limit voltage to the target voltage is linear. [4] The optical switch according to [1] or [2], wherein the change in voltage from the limit voltage to the target voltage is nonlinear. [5] The optical switch according to any one of [1] to [4], wherein the waveform generation unit controls the voltage waveform such that the change in thermal energy stored in the heater and its vicinity region is equal to the value obtained by integrating the power corresponding to the voltage applied to the heater over the transition time from the initial voltage to the target voltage. [6] The thermal energy stored in the heater and its vicinity region per unit of power is u, the power corresponding to the initial voltage is P1, the power corresponding to the target voltage is P2, and the power corresponding to the limit voltage (maximum voltage) is P Max The optical switch according to any one of [1] to [5], wherein the waveform generation unit generates a voltage waveform that satisfies the following equation (1), when the transition time from the initial voltage to the target voltage is t. [7] The thermal energy stored in the heater per unit of power is u, the power corresponding to the initial voltage is P1, the power corresponding to the target voltage is P2, and the power corresponding to the limit voltage (minimum voltage) is P MinThe optical switch according to any one of [1] to [6], wherein the waveform generation unit generates a voltage waveform that satisfies the following equation (2), when the transition time from the initial voltage to the target voltage is t. [8] The optical switch according to any one of [1] to [7], further comprising a power correction unit for correcting power corresponding to the initial voltage and power corresponding to the target voltage, wherein the power correction unit detects the amount of light based on a change in the phase of light and corrects the power by feeding back the detection result to the waveform generation unit. [9] The optical switch according to [8], wherein the power correction unit is connected between a device that changes the phase of light and an optical antenna, detects the output light amount of the optical switch, and corrects the power by feeding back the detection result to the waveform generation unit.

[10] The optical switch according to [8], wherein the power correction unit is connected to an optical antenna connected to a device that changes the phase of light, detects the amount of light emitted by the optical antenna, and corrects the power by feeding back the detection result to the waveform generation unit.

[11] The optical switch according to [8], wherein the power correction unit is connected to an optical antenna connected to a device that changes the phase of light, detects the amount of light received by the optical antenna, and corrects the power by feeding back the detection result to the waveform generation unit.

[12] The optical switch according to any one of [1] to

[11] , further comprising an amplitude determination unit that determines the amplitude of the voltage waveform applied to the heater, wherein the amplitude determination unit changes the amplitude in steps so that the transition time from the initial voltage to the target voltage is shortest, and determines the optimal amplitude.

[13] The optical switch according to

[12] , wherein the amplitude determination unit is connected between a device that changes the phase of light and an optical antenna, detects the output light amount of the optical switch, and determines the optimal amplitude by feeding back the detection result to the waveform generation unit.

[14] The optical switch according to

[12] , wherein the amplitude determination unit is connected to an optical antenna connected to a device that changes the phase of light, detects the amount of light emitted from the optical antenna, and determines the optimal amplitude by feeding back the detection result to the waveform generation unit.

[15] The optical switch according to

[12] , wherein the amplitude determination unit is connected to an optical antenna connected to a device that changes the phase of light, detects the amount of light received by the optical antenna, and determines the optimal amplitude by feeding back the detection result to the waveform generation unit.

[16] The optical switch according to any one of [1] to

[15] , comprising a Mach-Zehnder interferometer that changes the phase of light based on the thermo-optic effect.

[17] The optical switch according to any one of [1] to

[16] , wherein the heater contains TiN.

[18] A distance measuring device comprising an optical switch that changes the phase of light based on the thermo-optic effect, wherein the optical switch comprises a heater that changes the temperature of a region in which the refractive index changes due to the thermo-optic effect, and a waveform generation unit that generates a voltage waveform that controls the time change of the voltage applied to the heater, wherein the waveform generation unit changes the voltage from an initial voltage to a limit voltage in the shortest possible time, and then changes the voltage from the limit voltage to a target voltage.

[19] An electronic device comprising an optical switch that changes the phase of light based on the thermo-optic effect, wherein the optical switch comprises a heater that changes the temperature of a region in which the refractive index changes due to the thermo-optic effect, and a waveform generation unit that generates a voltage waveform that controls the time change of the voltage applied to the heater, wherein the waveform generation unit changes the voltage from an initial voltage to a limit voltage in the shortest possible time, and then changes the voltage from the limit voltage to a target voltage.

[0176] 1 Device (e.g., MZ interferometer) 11 Waveguide 12 Heater 13 Electrode 21 Waveform generation unit 22 Input circuit 23 Output circuit 24 Applied voltage 25 Power correction unit 26 Transmitting antenna 27 Receiving antenna 28 Amplitude determination unit 100 Optical switch 1000 Distance measuring device

Claims

1. An optical switch that changes the phase of light based on the thermo-optic effect, comprising: a heater that changes the temperature of a region in which the refractive index changes due to the thermo-optic effect; and a waveform generation unit that generates a voltage waveform to control the time change of the voltage applied to the heater, wherein the waveform generation unit changes the voltage from an initial voltage to a limit voltage (maximum or minimum voltage) in the shortest possible time, and then changes the voltage from the limit voltage to a target voltage.

2. The optical switch according to claim 1, wherein the shortest possible time is 0.01 microseconds or more and 100 microseconds or less.

3. The optical switch according to claim 1, wherein the change in the voltage from the limit voltage to the target voltage is linear.

4. The optical switch according to claim 1, wherein the change in the voltage from the limit voltage to the target voltage is nonlinear.

5. The optical switch according to claim 1, wherein the waveform generation unit controls the voltage waveform such that the change in thermal energy accumulated in the heater and its vicinity is equal to the value obtained by integrating the power corresponding to the voltage applied to the heater over the transition time from the initial voltage to the target voltage.

6. Let u be the thermal energy stored in the heater and its vicinity per unit of power, P1 be the power corresponding to the initial voltage, P2 be the power corresponding to the target voltage, and P2 be the power corresponding to the limit voltage (maximum voltage). Max The optical switch according to claim 1, wherein, when the transition time from the initial voltage to the target voltage is t, the waveform generation unit generates a voltage waveform that satisfies the following equation (1).

7. Let u be the thermal energy stored in the heater per unit of power, P1 be the power corresponding to the initial voltage, P2 be the power corresponding to the target voltage, and P be the power corresponding to the limit voltage (minimum voltage). Min The optical switch according to claim 1, wherein, when the transition time from the initial voltage to the target voltage is t, the waveform generation unit generates a voltage waveform that satisfies the following equation (2).

8. The optical switch according to claim 1, further comprising a power correction unit for correcting the power corresponding to the initial voltage and the power corresponding to the target voltage, wherein the power correction unit detects the amount of light based on a change in the phase of light and corrects the power by feeding the detection result back to the waveform generation unit.

9. The optical switch according to claim 8, wherein the power correction unit is connected between a device that changes the phase of light and an optical antenna, detects the output light amount of the optical switch, and corrects the power by feeding the detection result back to the waveform generation unit.

10. The optical switch according to claim 8, wherein the power correction unit is connected to an optical antenna connected to a device that changes the phase of light, detects the amount of light emitted from the optical antenna, and corrects the power by feeding the detection result back to the waveform generation unit.

11. The optical switch according to claim 8, wherein the power correction unit is connected to an optical antenna connected to a device that changes the phase of light, detects the amount of light received by the optical antenna, and corrects the power by feeding the detection result back to the waveform generation unit.

12. The optical switch according to claim 1, further comprising an amplitude determination unit that determines the amplitude of the voltage waveform applied to the heater, wherein the amplitude determination unit changes the amplitude in steps so as to minimize the transition time from the initial voltage to the target voltage, thereby determining the optimal amplitude.

13. The optical switch according to claim 12, wherein the amplitude determination unit is connected between a device that changes the phase of light and an optical antenna, detects the output light amount of the optical switch, and feeds the detection result back to the waveform generation unit to determine the optimal amplitude.

14. The optical switch according to claim 12, wherein the amplitude determination unit is connected to an optical antenna connected to a device that changes the phase of light, detects the amount of light emitted from the optical antenna, and determines the optimal amplitude by feeding the detection result back to the waveform generation unit.

15. The optical switch according to claim 12, wherein the amplitude determination unit is connected to an optical antenna connected to a device that changes the phase of light, detects the amount of light received by the optical antenna, and determines the optimal amplitude by feeding the detection result back to the waveform generation unit.

16. The optical switch according to claim 1, further comprising a Mach-Zehnder interferometer that changes the phase of light based on the thermo-optic effect.

17. The optical switch according to claim 1, wherein the heater includes TiN.

18. A distance measuring device comprising an optical switch that changes the phase of light based on the thermo-optic effect, wherein the optical switch includes a heater that changes the temperature of a region in which the refractive index changes due to the thermo-optic effect, and a waveform generation unit that generates a voltage waveform that controls the time change of the voltage applied to the heater, wherein the waveform generation unit changes the voltage from an initial voltage to a limit voltage in the shortest possible time, and then changes the voltage from the limit voltage to a target voltage.

19. An electronic device comprising an optical switch that changes the phase of light based on the thermo-optic effect, wherein the optical switch comprises a heater that changes the temperature of a region in which the refractive index changes due to the thermo-optic effect, and a waveform generation unit that generates a voltage waveform that controls the time change of the voltage applied to the heater, wherein the waveform generation unit changes the voltage from an initial voltage to a limit voltage in the shortest possible time, and then changes the voltage from the limit voltage to a target voltage.

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