Semiconductor device

Abstract

A semiconductor device according to the present technology comprises: a plurality of light emission units (17) that emit probe light to an object to be measured; heaters (18) that are respectively provided to each individual light emission unit (17) and that vary the emission angle of the probe light of the light emission unit (17); and a heater selection unit (25) that selects one heater (18) to be controlled from the plurality of heaters (18). The light emission units (17) are a plurality of optical antennas or a plurality of free-space optical couplers. The heater selection unit (25) is provided with: a first heater selection unit (26) that selects one heater group from a plurality of heater groups into which the plurality of heaters (18) are divided, and a second heater selection unit (27) that selects one heater from each of the heater groups. The heater (18) to be controlled is selected according to selection patterns of the first heater selection unit (26) and the second heater selection unit (27).

Description

Semiconductor device

[0001] This technology relates to a technology for semiconductor devices used in LiDAR (Light Detection and Ranging) and the like.

[0002] Various switches (selectors) are provided in LiDAR devices used in vehicles and the like. For example, in Non-Patent Document 1 below, the number of optical switches for guiding light to the transmission antenna is large, and the layout area on the driver's substrate for driving a large number of optical switches is widely adopted.

[0003] Daisuke Inoue, et al., "Solid-state optical scanning device using a beam combiner and switch array", Optica Vol.10, Issue 10, pp.1358-1365(2023), DOI:10.1364 / OPTICA.498402, [searched on August 7, 2024], Internet <https: / / opg.optica.org / optica / fulltext.cfm?uri=optica-10-10-1358&id=540786>

[0004] As a result, semiconductor devices such as LiDAR devices become larger, and significant limitations occur in the layout and the like when incorporating the semiconductor device into a product.

[0005] Therefore, the purpose of this technology is to miniaturize semiconductor devices.

[0006] The semiconductor device according to this technology comprises a plurality of light-emitting units that emit probe light toward an object to be measured, a heater provided for each of the light-emitting units that varies the emission angle of the probe light in the light-emitting unit, and a heater selection unit that selects one heater to be controlled from the plurality of heaters. The light-emitting units are a plurality of optical antennas or a plurality of optical space couplers, and the heater selection unit is provided with a first heater selection unit that selects one heater group from a plurality of heater groups in which the plurality of heaters are divided into a plurality of groups, and a second heater selection unit that selects one heater from each heater group. The heater to be controlled is selected by the selection pattern of the first heater selection unit and the second heater selection unit. For example, if there are as many heaters as there are light-emitting units for adjusting the emission angle of the light emitted from the light-emitting units, it is common to provide as many switches as there are heaters for selecting the heater to be controlled. However, with this configuration, for example, it is possible to select one heater to be controlled by a combination of the selection modes of the first heater selection unit and the second heater selection unit.

[0007] The semiconductor device according to this technology comprises an optical switch unit that has a plurality of phase shifters and directs light to one of a plurality of optical antennas or a plurality of optical space couplers, and a phase shifter selection unit that selects the phase shifter to be controlled from the plurality of phase shifters, wherein the optical switch unit is configured in a tree structure of multiple stages of optical switch circuits, and the optical switch circuit is configured to include a Mach-Zehnder interferometer or microring resonator having the phase shifter, and the phase shifters having the Mach-Zehnder interferometer or microring resonator arranged in the same stage of the tree structure of multiple stages are the phase shifters of the same stage, and the phase shifter selection unit is provided with a first phase shifter selection unit that selects one phase shifter group from a population of phase shifters of the same stage that is divided into a plurality of groups, and a second phase shifter selection unit that selects one phase shifter from each phase shifter group, and the phase shifter to be controlled is selected by the selection pattern of the first phase shifter selection unit and the second phase shifter selection unit.

[0008] This figure shows an example of the configuration of a distance measuring device according to an embodiment of this technology. This figure shows an example of the connection of the optical switch circuit provided in the optical switch section. This figure shows an example of the configuration of the optical switch circuit. This figure shows an example of the connection between the optical switch section and the slow light diffraction grating array section. This figure shows how the emission angle of the probe light emitted from the slow light diffraction grating is adjusted. This figure shows an example of a heater drive circuit provided for each slow light diffraction grating. This figure shows the state in which one heater has been selected as the control target by the heater drive circuit. This is an explanatory diagram of feedback control for suppressing control variations of the driver. This is a schematic diagram showing an example of the arrangement of the slow light diffraction grating array section and the optical switch section on a substrate. This figure shows an example of a phase shifter drive circuit provided for each optical switch circuit. This figure shows the state in which one phase shifter has been selected as the control target by the phase shifter drive circuit. This is a second embodiment of the heater drive circuit provided for each slow light diffraction grating, and shows an example of a configuration that includes a detection circuit for detecting abnormal current in the heater. This is a second embodiment of the phase shifter drive circuit provided for each optical switch circuit, and shows an example of a configuration that includes a detection circuit for detecting abnormal current in the phase shifter.

[0009] The embodiments will be described below in the following order: <1. Configuration of the semiconductor device> <2. Heater control in the slow-light diffraction grating> <3. Phase shifter control in the optical switch circuit> <4. Second embodiment> <5. Modified examples> <6. Summary> <7. This technology>

[0010] <1. Configuration of Semiconductor Device> As an example of a semiconductor device of this technology, we will give a distance measuring device 1. An example of the configuration of the distance measuring device 1 will be explained with reference to Figure 1.

[0011] The distance measuring device 1 measures the distance to the object OB by irradiating the object OB with probe light Lp and receiving the reflected light Lr.

[0012] The distance measuring device 1 is comprised of a silicon photonics chip 2, which uses silicon photonics, a technology that integrates optical waveguides made of silicon or the like onto a silicon chip, and a CMOS (Complementary Metal-Oxide-Semiconductor) chip 3, which uses semiconductor technology.

[0013] The siliphotochip 2 includes a ring laser 4 and a first optical branching circuit 5.

[0014] The light output from the ring laser 4 travels along an optical path formed on the siliphoto chip 2 and is input to the input terminal 5a of the first optical branching circuit 5.

[0015] The first optical branching circuit 5 is equipped with two output terminals 5b and 5c, and branched light is output from each of these output terminals 5b and 5c.

[0016] The siliphotochip 2 comprises a circulator 6, an optical switch unit 7, a slow light diffraction grating array unit 8, an optical coupler 9, and a light receiving unit 10.

[0017] The circulator 6 is equipped with three ports, designated as the first port 6a, the second port 6b, and the third port 6c.

[0018] The circulator 6 has the function of outputting light incident on the first port 6a from the second port 6b, and outputting light input from the second port 6b to the third port 6c.

[0019] The light output from one output terminal 5b of the first optical branching circuit 5 is input to the first port 6a of the circulator 6 and output from the second port 6b.

[0020] The optical switch unit 7 has one input port 7a and multiple output ports 7b. The input port 7a of the optical switch unit 7 is connected to the second port 6b of the circulator 6.

[0021] As shown in Figure 2, the optical switch section 7 is arranged such that multiple optical switch circuits 11 form a tree structure, or in other words, a tournament-like arrangement. Each optical switch circuit 11 has one input port 11a and two output ports 11b(1) and 11b(2).

[0022] Specifically, the optical switch unit 7 has one optical switch circuit 11 located at the first stage ST1 in the tree structure. The input port 11a of the optical switch circuit 11 located at the first stage ST1 is the input port 7a of the optical switch unit 7.

[0023] The optical switch unit 7 has two optical switch circuits 11 arranged in the second stage ST2 of the tree structure. The two output ports 11b of the optical switch circuit 11 arranged in the first stage ST1 are connected to the input ports 11a of the optical switch circuit 11 arranged in the second stage ST2, respectively.

[0024] Similarly, the third stage ST3 of the optical switch section 7 has four optical switch circuits 11, and the input port 11a of each optical switch circuit 11 is connected to the output port 11b of the preceding optical switch circuit 11.

[0025] In the optical switch section 7, eight optical switch circuits 11 are arranged in the fourth stage ST4, sixteen optical switch circuits 11 are arranged in the fifth stage ST5, and thirty-two optical switch circuits 11 are arranged in the sixth stage ST6.

[0026] The total number of output ports 11b of the optical switch circuit 11 located in the sixth stage ST6 of the optical switch section 7 is 64.

[0027] In this example, the 64 output ports 7b provided by the optical switch unit 7 are denoted as output port 7b(1) to output port 7b(64).

[0028] Various configurations are possible for each optical switch circuit 11 provided in the optical switch unit 7. Here, we will describe a case in which a configuration including a Mach-Zehnder interferometer 11A is adopted as an example of an optical switch circuit 11.

[0029] As shown in Figure 3, the Mach-Zehnder interferometer 11A is configured to include a pre-stage beam splitter 12 having two output ports, a first optical path 13 and a second optical path 14 connected to the two output ports of the pre-stage beam splitter 12, a phase shifter 15 that shifts the phase of the light passing through the second optical path 14, and a post-stage beam splitter 16 configured as a two-input, two-output device.

[0030] The pre-stage beam splitter 12 has an input port 12a and two output ports 12b(1) and 12b(2).

[0031] The input port 12a of the pre-stage beam splitter 12 is the input port 11a of the optical switch circuit 11.

[0032] The first optical path 13 is connected to the output port 12b(1) of the pre-stage beam splitter 12. The second optical path 14 is connected to the output port 12b(2) of the pre-stage beam splitter 12.

[0033] The subsequent beam splitter 16 has two input ports 16a(1) and 16a(2) and two output ports 16b(1) and 16b(2).

[0034] The first optical path 13 is connected to input port 16a(1). The second optical path 14 is connected to input port 16a(2).

[0035] The output port 16b(1) of the downstream beam splitter 16 is the output port 11b(1) of the optical switch circuit 11, and the output port 16b(2) is the output port 11b(2).

[0036] The Mach-Zehnder interferometer 11A can output light from only one of the two output ports 16b(1) and 16b(2) of the downstream beam splitter 16 by controlling the amount of shift by the phase shifter 15. In other words, the Mach-Zehnder interferometer 11A functions as a switch to switch the light output path.

[0037] The phase shifter 15 is, for example, a heater. That is, the phase shifter 15 changes the amount of phase shift of the light passing through the second optical path 14 by changing the temperature of the heater.

[0038] Note that the expression "output light from only one of the two output ports 16b(1) and 16b(2) of the subsequent beam splitter 16" indicates that the intensity of the output light is significantly stronger than the intensity of the light output from the other output port 16b. That is, this expression does not mean that no light is output from the other output port 16b.

[0039] Thus, in the optical switch section 7, the same number of phase shifters 15 as the number of Mach-Zehnder interferometers 11A in each stage exist as control targets.

[0040] The 64 output ports 7b in the optical switch section 7 are each connected to the input port 8a of the slow light diffraction grating array section 8 as shown in FIG. 1. That is, the slow light diffraction grating array section 8 is provided with 64 input ports 8a(1),..., 8a(64).

[0041] The slow light diffraction grating array section 8 includes one slow light diffraction grating 17 corresponding to one input port 8a. That is, the slow light diffraction grating array section 8 includes 64 slow light diffraction gratings 17 corresponding to 64 input ports 8a.

[0042] The 64 slow light diffraction gratings 17 are arranged at regular intervals separated in the second direction D2 orthogonal to the first direction D1 with the longitudinal direction as the first direction D1, for example, as shown in FIG. 4.

[0043] The slow light diffraction grating 17 is configured to have a heater 18.

[0044] In the following description, when the 64 slow light diffraction gratings 17 are denoted as slow light diffraction gratings 17(1), 17(2),..., 17(64), the corresponding heaters 18 are described as heaters 18(1), 18(2),..., 18(64), respectively.

[0045] As shown in FIG. 5, the slow light diffraction grating 17 can change the emission angle Ang of the light emitted from the slow light diffraction grating 17 into the space by changing the temperature of the heater 18. The slow light diffraction grating 17 functions as a light emission unit. The light emitted from the slow light diffraction grating 17 is used as the probe light Lp.

[0046] Thus, in the slow light diffraction grating array unit 8, the same number of heaters 18 as the slow light diffraction grating 17 exist as control targets.

[0047] The probe light Lp emitted from the slow light diffraction grating 17 into the air is reflected by the measurement object OB and enters the slow light diffraction grating 17 as the reflected light Lr.

[0048] The reflected light Lr incident on the slow light diffraction grating 17 travels in the opposite direction to when the probe light Lp was emitted. That is, the reflected light Lr advances from the input port 8a connected to the slow light diffraction grating 17 to the optical switch unit 7 via the output port 7b, and advances from the input port 7a to the second port 6b of the circulator 6.

[0049] The light input from the second port 6b of the circulator 6 is output from the third port 6c as described above (see FIG. 1).

[0050] The light branched in the first optical branching circuit 5 and output from the output terminal 5c is input to the input port of the optical coupler 9 as the reference light Lref.

[0051] Note that the optical coupler 9 is a two-input two-output coupler and has two input ports 9a(1), 9a(2) and two output ports 9b(1), 9b(2).

[0052] The reference light Lref output from the output terminal 5c of the first optical branching circuit 5 is input to the input port 9a(1).

[0053] Also, the reflected light Lr output from the third port 6c of the circulator 6 is input to the input port 9a(2) of the optical coupler 9.

[0054] In the optical coupler 9, the reference light Lref input from input port 9a(1) and the reflected light Lr input from input port 9a(2) interfere with each other, and the I signal Si and the Q signal Sq are output from the two output ports 9b. Here, it is assumed that the I signal Si is output from output port 9b(1) and the Q signal Sq is output from output port 9b(2).

[0055] The I signal Si and Q signal Sq output from the optical coupler 9 are incident on the light receiving unit 10 and received.

[0056] The light-receiving unit 10 is configured, for example, with a balanced photodetector 20 having two photodiodes 19i and 19q.

[0057] Photodiode 19i is a diode that receives incident light as the I signal Si, and photodiode 19q is a diode that receives incident light as the Q signal Sq.

[0058] The CMOS chip 3 contains circuits for controlling various control targets mounted on the siliphoto chip 2, as well as processing circuits for detection results.

[0059] Specifically, as shown in Figure 1, the CMOS chip 3 includes a laser control unit 21, an optical scan control unit 22, a detection unit 23, and a setting unit 24.

[0060] The laser control unit 21 includes a laser power control unit 21a that controls the intensity of the light emitted from the ring laser 4, and a laser frequency control unit 21b that controls the frequency of the emitted light.

[0061] Under the control of the laser frequency control unit 21b, the light emitted from the ring laser 4 becomes frequency-swept light whose frequency changes over time. In other words, the distance measuring device 1 is a device that performs distance measurement using a frequency-modulated continuous wave (FMCW).

[0062] The optical scan control unit 22 includes an optical switch control unit 22a and an emission angle control unit 22b.

[0063] The optical switch control unit 22a adjusts the phase of the light passing through the second optical path 14 by controlling the phase shifter 15, and selects the port from which the light is emitted between output port 16b(1) and output port 16b(2).

[0064] The optical switch control unit 22a performs a function to select the slow light diffraction grating 17 into which light is incident by controlling the phase shifter 15 for each stage in the optical switch unit 7.

[0065] The emission angle control unit 22b controls the emission angle Ang of the probe light Lp by controlling the heater 18 of the slow light diffraction grating array unit 8. As a result, the distance measuring device 1 achieves two-dimensional scanning of the probe light Lp relative to the object OB to be measured.

[0066] The detection unit 23 receives a bias voltage and other inputs suitable for the operation of the balanced photodetector 20. The detection unit 23 also receives the I signal Si and Q signal Sq output from the balanced photodetector 20, performs adjustments such as removing unwanted noise, and obtains an analog signal for calculating distance information.

[0067] The analog signal obtained by the detection unit 23 is output to a subsequent processing unit (not shown) to generate distance information.

[0068] The setting unit 24 performs various settings on the laser control unit 21, the optical scan control unit 22, and the detection unit 23. Specifically, the setting unit 24 sets the power of the light emitted from the ring laser 4, the frequency sweep range, the shift amount of the phase shifter 15 controlled by the optical switch unit 7, the temperature of the heater 18, and the bias voltage of the detection unit 23.

[0069] <2. Heater Control in Slow Light Diffraction Gratings> The control of the heater 18 provided for each slow light diffraction grating 17 in the slow light diffraction grating array section 8 will be explained with reference to Figure 6, etc.

[0070] The slow-light diffraction grating array section 8 is equipped with a plurality of heaters 18, which in this example is set to 64. The emission angle control section 22b in the optical scan control section 22 of the CMOS chip 3 has a heater selection section 25 that selects the heater 18 to be controlled from among these plurality of heaters 18.

[0071] Figure 6 shows the specific circuit configuration of the heater selection unit 25 and the heater 18. In Figure 6, the heater 18 is simply shown as a resistor. The rectangle surrounding the resistor represents the slow light diffraction grating 17.

[0072] The heater selection unit 25 includes a first heater selection unit 26 that selects one heater group 18G from heater groups 18G in which 64 heaters 18 are divided into several groups, and a second heater selection unit 27 that selects one heater 18 to be controlled from the selected first heater selection unit 26.

[0073] For example, of the 64 heaters 18(1), 18(2), ..., 18(64), the first eight heaters, 18(1) through 18(8), belong to the first heater group 18G(1).

[0074] Similarly, the eight heaters 18(9) to 18(16) belong to the second heater group 18G(2), the eight heaters 18(17) to 18(24) belong to the third heater group 18G(3), the eight heaters 18(25) to 18(32) belong to the fourth heater group 18G(4), the eight heaters 18(33) to 18(40) belong to the fifth heater group 18G(5), the eight heaters 18(41) to 18(48) belong to the sixth heater group 18G(6), the eight heaters 18(49) to 18(56) belong to the seventh heater group 18G(7), and the eight heaters 18(57) to 18(64) belong to the eighth heater group 18G(8).

[0075] Note that this grouping of 64 heaters 18 is merely one example.

[0076] Here, the eight heaters 18 belonging to each heater group 18G are designated as the first heater 18a, the second heater 18b, the third heater 18c, the fourth heater 18d, the fifth heater 18e, the sixth heater 18f, the seventh heater 18g, and the eighth heater 18h.

[0077] The second heater selection unit 27 selects one of the eight heaters 18, from the first heater 18a to the eighth heater 18h, which belong to each heater group 18G.

[0078] In other words, the first heater selection unit 26 selects one heater group 18G, and the second heater selection unit 27 selects one heater 18 from each of the heater groups 18G, thereby selecting one heater 18 to be controlled.

[0079] Although not explained in the previous description, the slow-light diffraction grating array section 8 has a diode 28 connected in series with each heater 18 to prevent reverse current flow. The positive terminal of the heater 18 is connected to the cathode of the diode 28.

[0080] As shown in Figure 6, the first heater selection unit 26 is provided as a first heater selection switch 29(1), ..., first heater selection switch 29(8) for each heater group 18G. In other words, the first heater selection unit 26 is equipped with eight first heater selection switches 29.

[0081] The ejection angle control unit 22b includes a plurality of drivers 30 located on the negative side of the first heater selection switch 29.

[0082] As for the driver 30, for example, there is a driver 30(1) provided for four groups from heater group 18G(1) to heater group 18G(4), and a driver 30(2) provided for four groups from heater group 18G(5) to heater group 18G(8).

[0083] In other words, one driver 30 is provided for every predetermined number of first heater selection switches 29.

[0084] The negative terminal of each driver 30 is connected to a negative power source such as ground.

[0085] As shown in Figure 6, when one of the eight first heater selection switches 29 provided in the first heater selection unit 26 is controlled to the ON state, the negative terminals of the eight heaters 18 connected in parallel to the positive terminal side of the first heater selection switch 29 that is controlled to the ON state are connected to the driver 30.

[0086] Furthermore, as shown in Figure 6, the second heater selection unit 27 is provided as a second heater selection switch 31 connected to each heater 18 of the heater group 18G.

[0087] Specifically, the second heater selection unit 27 includes a second heater selection switch 31(1) connected in parallel to the positive terminal side of the first heater 18a in each of the eight heater groups 18G, a second heater selection switch 31(2) connected in parallel to the positive terminal side of the second heater 18b in each, a second heater selection switch 31(3) connected in parallel to the positive terminal side of the third heater 18c in each, a second heater selection switch 31(4) connected in parallel to the positive terminal side of the fourth heater 18d in each, a second heater selection switch 31(5) connected in parallel to the positive terminal side of the fifth heater 18e in each, a second heater selection switch 31(6) connected in parallel to the positive terminal side of the sixth heater 18f in each, a second heater selection switch 31(7) connected in parallel to the positive terminal side of the seventh heater 18g in each, and a second heater selection switch 31(8) connected in parallel to the positive terminal side of the eighth heater 18h in each.

[0088] The positive terminal side of each second heater selection switch 31 provided in the second heater selection unit 27 is connected to the positive power supply.

[0089] Drivers 30(1) and 30(2) function as constant current sources that supply a constant current to the heater 18 to be controlled.

[0090] The distance measuring device 1 includes a first heater selection unit 26 in the silicon photochip 2 that switches the connection configuration of the negative electrode side of the heater 18, and a second heater selection unit 27 that switches the connection configuration of the positive electrode side, thereby enabling the selection of one heater 18 to be controlled.

[0091] For example, Figure 7 shows a state in which the optical switch control unit 22a controls only the first heater selection switch 29(1) of the eight first heater selection switches 29 provided in the first heater selection unit 26 to be in the ON state, and controls only the second heater selection switch 31(8) of the eight second heater selection switches 31 provided in the second heater selection unit 27 to be in the ON state.

[0092] In this state, a current controlled by the driver 30(1) is applied to the eighth heater 18h, i.e., heater 18(8), which belongs to the heater group 18G(1), and is adjusted to a predetermined temperature.

[0093] Furthermore, control variations may exist between driver 30(1) and driver 30(2).

[0094] To reduce this control variation, the CMOS chip 3 may be provided with a voltage monitoring unit 32 corresponding to each driver 30.

[0095] For example, as shown in Figure 8, a voltage monitoring unit 32(1) corresponding to driver 30(1) is inserted between driver 30(1) and ground. Also, a voltage monitoring unit 32(2) corresponding to driver 30(2) is inserted between driver 30(2) and ground.

[0096] Furthermore, the emission angle control unit 22b of the CMOS chip 3 is provided with a feedback control unit 33 based on the detected voltage in the voltage monitoring unit 32(1) and the voltage monitoring unit 32(2).

[0097] The feedback control unit 33 performs feedback control to either driver 30(1) or driver 30(2) based on the voltage detected by each voltage monitoring unit 32.

[0098] As explained above, in the CMOS chip 3, the total number of first heater selection switches 29, which serve as the first heater selection unit 26, and second heater selection switches 31, which serve as the second heater selection unit 27, is 16.

[0099] As a result, the distance measuring device 1 achieves a reduction in electronic components and circuit area compared to a case where 64 switches are provided to control each of the 64 heaters 18, which are provided together with the slow light diffraction grating 17, to be in an ON or OFF state.

[0100] Furthermore, by placing either the first heater selection switch 29 or the second heater selection switch 31 on the positive side of the heater 18 and the other on the negative side, the supply of current to the heater 18 can be cut off even if a malfunction occurs on either the positive or negative side. This contributes to improving the safety of the distance measuring device 1.

[0101] <3. Phase Shifter Control in Optical Switch Circuits> The configuration of the first heater selection switch 29 and the second heater selection switch 31 for selecting the heater 18 to be controlled is also applicable to the configuration for selecting the phase shifter 15 to be controlled in the optical switch circuit 11.

[0102] In the above description, which uses Figures 2 and 4, etc., the configuration of the optical switch unit 7 is shown in which all the optical switch circuits 11 are arranged on one side with respect to the slow light diffraction grating array unit 8 mounted on the substrate.

[0103] This section describes an example in which some of the optical switch circuits 11 are arranged on one side of the slow-light diffraction grating array 8 on the substrate, and the remaining optical switch circuits 11 are arranged on the other side. By arranging the optical switch circuits 11 on both sides of the slow-light diffraction grating array 8, it is possible to reduce the mounting area of ​​the substrate.

[0104] Figure 9 shows an example of a specific arrangement of the optical switch circuit 11. The optical switch section 7 is composed of one optical switch circuit 11 that constitutes the first stage ST1 in the tree structure, and two parts that form the tree structure from the second stage ST2 onwards. These two parts are referred to as the first optical switch section 34A and the second optical switch section 34B.

[0105] The first optical switch unit 34A is connected to the output port 11b(1) of the optical switch circuit 11. The second optical switch unit 34B is connected to the output port 11b(2) of the optical switch circuit 11.

[0106] The first optical switch unit 34A is located on one side of the slow light diffraction grating array unit 8 on the substrate on which the slow light diffraction grating array unit 8 is mounted, and the second optical switch unit 34B is located on the other side of the slow light diffraction grating array unit 8. In other words, the first optical switch unit 34A and the second optical switch unit 34B are located on opposite sides of the slow light diffraction grating array unit 8.

[0107] The first optical switch section 34A is part of the configuration of the second stage ST2 in the optical switch section 7 and has a tree structure of optical switch circuits 11 consisting of five stages, with one optical switch circuit 11 which is the first stage of the tree structure in the first optical switch section 34A at the top.

[0108] Specifically, in the first optical switch section 34A, one optical switch circuit 11 is arranged in the first stage, two optical switch circuits 11 are arranged in the second stage, four optical switch circuits 11 are arranged in the third stage, eight optical switch circuits 11 are arranged in the fourth stage, and sixteen optical switch circuits 11 are arranged in the fifth stage.

[0109] Similarly, in the second optical switch section 34B, the optical switch circuit 11 is configured in a tree structure from the first to the fifth stage.

[0110] The first optical switch unit 34A has 32 output ports, each of which is an output port 7b of the optical switch unit 7. The 32 output ports of the first optical switch unit 34A are designated as 7b(1), 7b(2), ..., 7b(32).

[0111] Similarly, the second optical switch unit 34B has 32 output ports, each of which is an output port 7b of the optical switch unit 7. The 32 output ports of the second optical switch unit 34B are designated as 7b(33), 7b(34), ..., 7b(64).

[0112] The output port 7b of the first optical switch unit 34A is an optical waveguide that guides light to the odd-numbered slow-light diffraction gratings 17.

[0113] Furthermore, the output port 7b of the second optical switch unit 34B is configured as an optical waveguide that guides light to the even-numbered slow-light diffraction gratings 17.

[0114] In the tree structure of the optical switch circuits 11 that constitute the optical switch section 7, one optical switch circuit 11 is controlled at each stage. That is, since the first stage ST1 of the optical switch section 7 contains only one optical switch circuit 11, that one optical switch circuit 11 is always controlled.

[0115] Furthermore, the second stage ST2 in the optical switch section 7 includes two optical switch circuits 11, and one of the two optical switch circuits 11 is the target of control.

[0116] Furthermore, the third stage ST3 in the optical switch section 7 includes four optical switch circuits 11, and one of the four optical switch circuits 11 is the target of control.

[0117] Similarly, in the fourth stage ST4, the fifth stage ST5, and the sixth stage ST6, one optical switch circuit 11 is controlled in each of these stages.

[0118] The optical switch circuit 11, through which light from the ring laser 4 does not pass, is not subject to control and can be left uncontrolled.

[0119] In the optical switch section 7, one optical switch circuit 11 is appropriately controlled at each stage of the tree structure, thereby guiding the light from the ring laser 4 to the desired slow-light diffraction grating 17.

[0120] In each stage of the tree structure of the optical switch section 7, a connection configuration similar to that used for controlling the heater 18 of the slow light diffraction grating 17 is adopted as appropriate, depending on the number of optical switch circuits 11 included. Specifically, each stage of the tree structure of the optical switch section 7 includes one or more optical switch circuits 11, and each optical switch circuit 11 is provided with a phase shifter 15 to be controlled.

[0121] Therefore, in each stage of the tree structure of the optical switch section 7, an appropriate connection configuration is adopted according to the number of phase shifters 15. This will be explained in detail with reference to Figure 10. Note that the phase shifter 15 is composed of, for example, a heater element, and the amount of phase shift is made variable by changing the temperature of the heater element. In Figure 10, the phase shifter 15 is simply shown as a resistor.

[0122] The distance measuring device 1 includes a phase shifter selection unit 35 for selecting the phase shifter 15 to be controlled.

[0123] The phase shifter selection unit 35 includes a first phase shifter selection unit 36 ​​and a second phase shifter selection unit 37 for selecting the phase shifters 15 included in each stage of the tree structure in the optical switch unit 7.

[0124] Furthermore, taking the sixth stage ST6 of the optical switch unit 7 as an example, the first phase shifter selection unit 36 ​​provided in correspondence with the sixth stage ST6 will be referred to as the first phase shifter selection unit 36(6), and the second phase shifter selection unit 37 provided in correspondence with the sixth stage ST6 will be referred to as the second phase shifter selection unit 37(6).

[0125] Since the first stage ST1, second stage ST2, and third stage ST3 of the optical switch unit 7 contain four or fewer phase shifters 15, only one of the first phase shifter selection unit 36 ​​and the second phase shifter selection unit 37 is provided.

[0126] For example, in this example, only the first phase shifter selection unit 36(1) is provided in order to select the phase shifter 15 included in the first stage ST1.

[0127] The first phase shifter selection unit 36(1) consists of a single first phase shifter selection switch 38. The positive side of the first phase shifter selection switch 38 is connected to the phase shifter 15. The optical switch control unit 22a includes a driver 39 connected to the negative side of the first phase shifter selection switch 38.

[0128] The driver 39 functions as a constant current source that supplies a constant current to the phase shifter 15. The negative terminal side of the driver 39 is connected to a negative power source such as ground.

[0129] The positive terminal side of the phase shifter 15 of the first stage ST1 is connected to the positive power supply.

[0130] Furthermore, only the first phase shifter selection unit 36(2) is provided in order to select the phase shifter 15 included in the second stage ST2.

[0131] The first phase shifter selection unit 36(2) consists of two first phase shifter selection switches 38. The positive side of each first phase shifter selection switch 38 is connected to a different phase shifter 15. The negative side of the first phase shifter selection switch 38 is connected to the negative power supply via a driver 39.

[0132] The positive terminal side of the phase shifter 15 in the second stage ST2 is connected to the positive power supply.

[0133] Furthermore, only the first phase shifter selection unit 36(3) is provided in order to select the phase shifter 15 included in the third stage ST3.

[0134] The first phase shifter selection unit 36(3) consists of four first phase shifter selection switches 38. The positive side of each first phase shifter selection switch 38 is connected to a different phase shifter 15. The negative side of each first phase shifter selection switch 38 is connected to the negative power supply via a driver 39.

[0135] The positive terminal side of the phase shifter 15 in the third stage ST3 is connected to the positive power supply.

[0136] As shown in Figure 10, the positive terminals of all phase shifters 15 included in the first stage ST1, second stage ST2, and third stage ST3 of the optical switch unit 7 may be connected to the same positive power supply.

[0137] As can be seen from the connection example of the first stage ST1, second stage ST2, and third stage ST3, when the number of phase shifters 15 that can be selected as the control target is four or less, even if the switches are separated on the positive and negative sides of the phase shifter 15 and connected in a matrix, the number of switches cannot be reduced. Therefore, it is sufficient to provide the same number of switches as the number of phase shifters 15 on either the positive or negative side of the phase shifter 15.

[0138] For the fourth stage ST4, fifth stage ST5, and sixth stage ST6 of the optical switch section 7, both a first phase shifter selection unit 36 ​​and a second phase shifter selection unit 37 are provided to reduce the number of electronic components.

[0139] Specifically, the optical switch control unit 22a is configured to select one of the eight phase shifters 15 included in the fourth stage ST4, and includes a first phase shifter selection unit 36(4) and a second phase shifter selection unit 37(4).

[0140] In the example shown in Figure 10, the first phase shifter selection unit 36(4) is equipped with two first phase shifter selection switches 38 to select one phase shifter group 15G from two phase shifter groups 15G in which eight phase shifters 15 are divided into four groups each.

[0141] The second phase shifter selection unit 37(4) is equipped with four second phase shifter selection switches 40 to select one phase shifter 15 to be controlled from four phase shifters 15 included in a selected phase shifter group 15G.

[0142] In the first phase shifter selection unit 36(4), one first phase shifter selection switch 38 is controlled to the ON state, and in the second phase shifter selection unit 37(4), one second phase shifter selection switch 40 is controlled to the ON state, thereby selecting one phase shifter 15 as the control target in the fourth stage ST4.

[0143] The negative terminal side of each first phase shifter selection unit 36 ​​is connected to the negative power supply via the driver 39.

[0144] Furthermore, the positive terminal side of each second phase shifter selection unit 37 is connected to the positive power supply.

[0145] Furthermore, a diode 41 is provided between the phase shifter 15 and the second phase shifter selection switch 40 to prevent reverse current flow. The positive terminal side of the phase shifter 15 is connected to the cathode of the diode 41.

[0146] The optical switch control unit 22a is configured to select one of the 16 phase shifters 15 included in the fifth stage ST5 of the optical switch unit 7, and includes a first phase shifter selection unit 36(5) and a second phase shifter selection unit 37(5).

[0147] The first phase shifter selection unit 36(5) shown in Figure 10 is equipped with four first phase shifter selection switches 38 to select one phase shifter group 15G from four phase shifter groups 15G, each of which contains 16 phase shifters 15 divided into four groups of four.

[0148] The second phase shifter selection unit 37(5) is equipped with four second phase shifter selection switches 40 to select one phase shifter 15 to be controlled from four phase shifters 15 included in a selected phase shifter group 15G.

[0149] A diode 41 is provided between the phase shifter 15 and the second phase shifter selection switch 40 to prevent reverse current flow.

[0150] The connection configuration of the first phase shifter selector switch 38 and the second phase shifter selector switch 40 is the same as that of the fourth stage ST4, so the explanation is omitted.

[0151] The first phase shifter selection unit 36(6) shown in Figure 10 is equipped with four first phase shifter selection switches 38 to select one phase shifter group 15G from four phase shifter groups 15G, each of which contains 32 phase shifters 15 divided into groups of eight.

[0152] The second phase shifter selection unit 37(6) is equipped with eight second phase shifter selection switches 40 to select one phase shifter 15 to be controlled from eight phase shifters 15 included in a selected phase shifter group 15G.

[0153] A diode 41 is provided between the phase shifter 15 and the second phase shifter selection switch 40 to prevent reverse current flow.

[0154] The connection configuration of the first phase shifter selector switch 38 and the second phase shifter selector switch 40 is the same as that of the fourth stage ST4, so the explanation is omitted.

[0155] In any of the fourth stage ST4, fifth stage ST5, and sixth stage ST6 of the optical switch unit 7, it is possible to reduce the number of electronic components by adopting a configuration in which one phase shifter 15 is selected as the control target by a combination of selection modes of the first phase shifter selection unit 36 ​​and the second phase shifter selection unit 37, rather than providing the same number of switches as the number of phase shifters 15.

[0156] Figure 11 shows an example of how one phase shifter 15 is selected at each stage of the optical switch unit 7. By controlling the one phase shifter 15 selected at each stage of the optical switch unit 7, the light emitted from the ring laser 4 is guided to a single slow light diffraction grating 17.

[0157] The phase shifter selection unit 35 is configured such that either the first phase shifter selection switch 38 or the second phase shifter selection switch 40 is placed on the positive side of the phase shifter 15 and the other on the negative side. This configuration allows for the interruption of the current supply to the phase shifter 15 even if a malfunction occurs on either the positive or negative side. This contributes to improving the safety of the distance measuring device 1.

[0158] <4. Second Embodiment> The distance measuring device 1 according to the second embodiment differs in the configuration of the emission angle control unit 22b. Specifically, this will be explained with reference to Figure 12.

[0159] The emission angle control unit 22b is equipped with a detection circuit for detecting abnormal currents in the heater 18. The detection circuit includes a first detection circuit 42 provided on the negative electrode side of the heater 18 and a second detection circuit 43 provided on the positive electrode side of the heater 18.

[0160] The first detection circuit 42 is provided in the same number as each of the multiple first heater selection switches 29 that the emission angle control unit 22b has, and is positioned between the heater 18 and the first heater selection switches 29.

[0161] The second detection circuit 43 is provided in the same number as each of the multiple second heater selection switches 31 that the emission angle control unit 22b has, and is positioned between the heater 18 and the second heater selection switches 31.

[0162] For example, if the first heater selection switch 29 is short-circuited to the heater 18, the second heater selection switch 31, which is located on the positive side of the heater 18, can be controlled to the OFF state to prevent an overcurrent from continuing to flow through the heater 18.

[0163] A similar configuration for detecting abnormalities can also be applied to the optical switch control unit 22a. This is specifically shown in Figure 13.

[0164] The optical switch control unit 22a is equipped with a detection circuit for detecting abnormal currents in the phase shifter 15. The detection circuit includes a first detection circuit 44 provided on the negative electrode side of the phase shifter 15 and a second detection circuit 45 provided on the positive electrode side of the phase shifter 15.

[0165] The first detection circuit 44 is provided in the same number as each of the multiple first phase shifter selection switches 38 in the optical switch control unit 22a, and is positioned between the phase shifter 15 and the first phase shifter selection switches 38.

[0166] The second detection circuit 45 is provided in the same number as each of the multiple second phase shifter selection switches 40 in the optical switch control unit 22a, and is positioned between the phase shifter 15 and the second phase shifter selection switches 40.

[0167] For example, if the first phase shifter selection switch 38 is short-circuited to the phase shifter 15, the second phase shifter selection switch 40, which is located on the positive side of the phase shifter 15, can be controlled to the OFF state to prevent overcurrent from continuing to flow through the phase shifter 15.

[0168] The multiple drivers 39 provided by the optical switch control unit 22a may have control variations, similar to the driver 30 provided by the emission angle control unit 22b.

[0169] The optical switch control unit 22a may be provided with a voltage monitoring unit and a feedback control unit corresponding to each driver 39 in order to reduce control variations in the driver 39.

[0170] The voltage monitoring unit can be implemented by applying the configuration shown in Figure 8 to Figure 13, and inserting a voltage monitoring unit corresponding to the driver 39 between the driver 39 and ground.

[0171] Furthermore, the feedback control unit performs feedback control on the driver 39 based on the voltage detected by the voltage monitoring unit.

[0172] <5. Modified Configuration> In the example shown in Figure 6, the number of switches is minimized by making the number of first heater selection switches 29 and the number of second heater selection switches 31 the same. However, the configurations of the first heater selection switches 29 and the second heater selection switches 31 are not necessarily the same.

[0173] For example, the circuit configurations of the first heater selection switch 29 and the second heater selection switch 31 may differ, resulting in different footprints on the circuit board. In such cases, instead of making the number of first heater selection switches 29 and second heater selection switches 31 approximately equal, a difference may be introduced. For example, if the circuit area of ​​the second heater selection switch 31 is smaller than that of the first heater selection switch 29, a configuration may be used to select one heater 18 from among 64 heaters 18 by providing four first heater selection switches 29 and sixteen second heater selection switches 31.

[0174] <6. Summary> As explained above, the distance measuring device 1 as a semiconductor device comprises a plurality of light emitting units (slow light diffraction gratings 17) that emit probe light Lp toward the object to be measured OB, a heater 18 provided for each light emitting unit that varies the emission angle Ang of the probe light Lp at the light emitting unit, and a heater selection unit 25 that selects one heater 18 to be controlled from the plurality of heaters 18. The light emitting units are a plurality of optical antennas (slow light diffraction gratings 17) or a plurality of optical space couplers, and the heater selection unit 25 is provided with a first heater selection unit 26 that selects one heater group 18G from a plurality of heater groups 18G in which the plurality of heaters 18 are divided into a plurality of groups, and a second heater selection unit 27 that selects one heater 18 from each heater group 18G. The heater 18 to be controlled is selected by the selection pattern of the first heater selection unit 26 and the second heater selection unit 27. For example, if heaters 18 for adjusting the emission angle Ang of the probe light Lp emitted from the slow light diffraction grating 17 are provided in equal numbers to the number of slow light diffraction gratings 17, it is common to provide as many switches as there are heaters 18 for selecting the heater 18 to be controlled. However, with this configuration, it is possible to select one heater 18 to be controlled by, for example, a combination of selection modes of the first heater selection unit 26 and the second heater selection unit 27. Therefore, it is possible to simplify the configuration of the first heater selection unit 26 and the second heater selection unit 27, and reduce the number of electronic components that make up the circuit. In other words, it is possible to reduce the circuit area by reducing the electronic components and wiring related to the distance measuring device 1, and to improve the freedom of layout. Furthermore, it is possible to reduce costs by reducing the number of electronic components. In particular, if the wiring layer can be reduced by reducing the wiring, it is possible to reduce costs by reducing the number of layers on the circuit board.

[0175] As explained with reference to Figure 6, etc., the first heater selection unit 26 in the distance measuring device 1 as a semiconductor device may have a plurality of first heater selection switches 29, and the second heater selection unit 27 may have a plurality of second heater selection switches 31. When there are many heaters 18, the number of switches can be less than the number of heaters 18. That is, the number of electronic components can be reduced compared to a configuration in which there are as many switches as there are heaters 18.

[0176] As explained with reference to Figure 6, the first heater selection unit 26 has N first heater selection switches 29, and the second heater selection unit 27 has M second heater selection switches 31, where N and M are both positive integers, and the product of N and M may match the number of light emitting units (slow light diffraction gratings 17). For example, when 64 heaters 18 are arranged with 64 slow light diffraction gratings 17, eight first heater selection switches 29 and eight second heater selection switches 31 are provided. This makes it possible to create 64 different states by combining the selection modes of the first heater selection switches 29 and the selection modes of the second heater selection switches 31. Then, by adopting a configuration in which each of the 64 heaters 18 is selected individually according to the 64 selection modes, it is possible to use only 16 switches compared to using 64 switches.

[0177] As explained with reference to Figure 6, the difference between N and M may be the smallest possible combination of values ​​for N and M. For example, if there are 64 slow-light diffraction gratings 17, setting M to 16 and N to 4 creates 64 possible selection modes, but the difference between M and N is 12. With this configuration, setting both M and N to 8 creates 64 possible selection modes, and the difference between M and N becomes 0. This allows the number of switches to be 16, which is less than 20, minimizing the number of electronic components. Also, for example, if there are 56 slow-light diffraction gratings 17, setting either M or N to 8 and the other to 7 results in a difference of 1 between M and N. This is considered a smaller difference than any other integer combination.

[0178] As explained with reference to Figure 6, etc., in the distance measuring device 1 as a semiconductor device, the first heater selection unit 26 and the second heater selection unit 27 may be arranged such that one is on the positive side of the heater 18 and the other is on the negative side of the heater 18. For example, if the terminal on the negative side (ground side) of the heater 18 is short-circuited with ground, the selection unit arranged on the positive side (power supply side) can be controlled so that the short-circuited heater 18 is not selected, thereby preventing an overcurrent from flowing to the heater 18.

[0179] As explained with reference to Figure 12, the distance measuring device 1 may be equipped with a detection circuit (first detection circuit 42, second detection circuit 43) for detecting faults, provided for each first heater selection switch 29 and second heater selection switch 31. For example, if a switch is provided for each heater 18 provided in accordance with the slow light diffraction grating 17, it is necessary to provide the same number of detection circuits as the slow light diffraction grating 17. However, with this configuration, if there are many slow light diffraction gratings 17, the number of switches provided is much less than the number of slow light diffraction gratings 17, so the number of detection circuits can also be reduced to less than the number of slow light diffraction gratings 17. In other words, the scale of the fault detection circuit can be reduced, and the circuit area can be reduced.

[0180] As explained with reference to Figures 6 and 8, the distance measuring device 1 as a semiconductor device includes a driver 30 provided for each predetermined number of first heater selection switches 29, and a voltage monitoring unit 32 provided in correspondence with the driver 30. The driver 30 may apply a feedback-controlled current to the heater 18 based on the monitoring results from the voltage monitoring unit 32. This eliminates control variations between drivers 30 and improves distance measuring accuracy.

[0181] As explained with reference to Figure 6, etc., the distance measuring device 1 as a semiconductor device is equipped with a diode 28 provided for each heater 18, and the cathode of the diode 28 may be connected to the input side of the heater 18. This makes it possible to adopt a configuration that prevents the drive current from flowing to a heater 18 other than the intended heater 18 depending on the selection mode of the first heater selection unit 26 and the second heater selection unit 27.

[0182] As explained with reference to Figure 2, etc., the distance measuring device 1 as a semiconductor device includes an optical switch unit 7 that guides light to one of a plurality of light emitting units (slow light diffraction gratings 17), and the optical switch unit 7 may have optical switch circuits 11 arranged in a multi-stage tree structure. For example, one optical switch circuit 11 is arranged in the first stage ST1, two optical switch circuits 11 are arranged in the second stage ST2, and four optical switch circuits 11 are arranged in the third stage ST3. That is, the optical switch unit 7 is controlled so that only one path is selected at each stage, so that light is ultimately guided to one slow light diffraction grating 17. With such a configuration, an optical switch unit 7 with a multi-stage tree structure can be realized.

[0183] As explained with reference to Figure 3, the optical switch circuit 11 in the distance measuring device 1 as a semiconductor device may be configured to include a Mach-Zehnder interferometer 11A having a phase shifter 15 or a microring resonator. In this way, the optical switch circuit 11 functions as an optical switch that selects one of two optical paths and guides the light by adjusting the amount of shift by the phase shifter 15. An optical switch using a microring resonator can be realized by utilizing the phenomena of reinforcement and cancellation between two waves in a ring resonator.

[0184] As explained with reference to Figure 10, etc., the ranging device 1 as a semiconductor device includes a phase shifter selection unit 35 that selects one phase shifter 15 to be controlled from among the phase shifters 15 of the Mach-Zehnder interferometer 11A or microring resonator arranged in the same stage of a multi-stage tree structure. The phase shifter selection unit 35 may include a first phase shifter selection unit 36 ​​that selects one phase shifter group 15G from a group of phase shifter groups 15G in which the phase shifters 15 in the same stage that constitute the selection population are divided into multiple groups, and a second phase shifter selection unit 37 that selects one phase shifter 15 from each of the phase shifter groups 15G. That is, the configuration for selecting one from multiple phase shifters 15 arranged in the same stage is similar to the configuration of the heater selection unit 25 that selects one from multiple heaters 18 provided together with multiple slow-light diffraction gratings 17. By adopting the same configuration at each stage of the phase shifter 15, it is possible to reduce the size of the optical switch unit 7 for guiding light to one slow-light diffraction grating 17, thereby improving the freedom of layout. Furthermore, reducing the size of the optical switch unit 7 can lead to cost reductions. In particular, if the wiring layers can be reduced by reducing the wiring related to the optical switch unit 7, cost reductions can be achieved by reducing the number of layers on the circuit board.

[0185] As explained with reference to Figure 10, etc., the phase shifter selection unit 35, which has a first phase shifter selection unit 36 ​​and a second phase shifter selection unit 37, may be provided in accordance with stages where the number of phase shifters 15 to be arranged is greater than or equal to a predetermined number. That is, the phase shifter selection unit 35 provided in accordance with stages where the number of optical paths to be selected is a predetermined number, for example, 8 or more, will have a first phase shifter selection unit 36 ​​and a second phase shifter selection unit 37. As a result, stages with a small number of optical paths to be selected will have a configuration with the same number of switches as the number of optical paths, and stages with a large number of optical paths to be selected will have a configuration with fewer switches than the number of optical paths. Therefore, the number of electronic components constituting the phase shifter selection unit 35 can be reduced, and the circuit configuration can be reduced. In addition, the circuit area related to the phase shifter selection unit 35 can be reduced, and the degree of freedom in layout can be improved. Furthermore, by reducing the number of electronic components, it is possible to reduce costs. In particular, if the number of wiring layers can be reduced by reducing the amount of wiring, cost reductions can be achieved by reducing the number of layers on the circuit board.

[0186] As explained with reference to Figure 9, the optical switch section 7 in the distance measuring device 1 as a semiconductor device has a first optical switch section 34A which includes a part of the plurality of optical switch circuits 11, and a second optical switch section 34B which includes all of the remaining optical switch circuits 11. The first optical switch section 34A and the second optical switch section 34B are each arranged in a multi-stage tree structure, and the first optical switch section 34A may be positioned on one side of the plurality of light emitting sections (slow light diffraction gratings 17) on the substrate, while the second optical switch section 34B may be positioned on the opposite side of the plurality of light emitting sections from the first optical switch section 34A on the substrate. This eliminates the need to mount all the optical switch circuits 11 on one side of the slow light diffraction grating group 17. Therefore, the circuit configuration of the optical switch section 7 can be made compact, and the overall size of the distance measuring device 1 can be reduced.

[0187] As explained with reference to Figure 9, etc., the first optical switch unit 34A in the distance measuring device 1 as a semiconductor device is capable of directing light to the odd-numbered light emitters (slow light diffraction gratings 17) among a plurality of light emitters (slow light diffraction gratings 17) arranged in a row on the substrate, and the second optical switch unit 34B may be capable of directing light to the even-numbered light emitters (slow light diffraction gratings 17) among a plurality of light emitters (slow light diffraction gratings 17) arranged in a row on the substrate. By making each slow light diffraction grating 17 to which light is guided by the first optical switch unit 34A located on one side of the group of slow light diffraction gratings 17 skip one, the circuit configuration of the optical switch unit 7 can be made more compact, and the overall size of the distance measuring device 1 can be reduced.

[0188] As explained with reference to the figures, the light-emitting section of the distance measuring device 1 as a semiconductor device may be a slow-light diffraction grating 17. This allows for the suitable realization of the distance measuring device 1 as a semiconductor device described above.

[0189] As explained with reference to Figure 10, etc., the distance measuring device 1 as a semiconductor device may be provided with a diode 41 whose cathode is connected to the input side of the phase shifter 15 for each phase shifter 15. This makes it possible to adopt a configuration that prevents the drive current from flowing to a phase shifter 15 other than the intended phase shifter 15 depending on the selection mode of the first phase shifter selection unit 36 ​​and the second phase shifter selection unit 37.

[0190] As explained with reference to Figure 10, etc., in the distance measuring device 1 as a semiconductor device, the first phase shifter selection unit 36 ​​and the second phase shifter selection unit 37 may be arranged such that one is on the positive terminal side of the phase shifter 15 and the other is on the negative terminal side of the phase shifter 15. For example, if the terminal on the negative terminal side (ground side) of the phase shifter 15 is short-circuited with ground, the selection unit arranged on the positive terminal side (power supply side) can be controlled so that the short-circuited phase shifter 15 is not selected, thereby preventing an overcurrent from flowing through the phase shifter 15.

[0191] As explained with reference to Figure 13, etc., in the distance measuring device 1 as a semiconductor device, the first phase shifter selection unit 36 ​​has a plurality of first phase shifter selection switches 38, and the second phase shifter selection unit 37 has a plurality of second phase shifter selection switches 40, and each of the first phase shifter selection switches 38 and the second phase shifter selection switches 40 may be provided with a detection circuit (first detection circuit 44, second detection circuit 45) for detecting faults. For example, if a phase shifter 15 is provided for each optical switch circuit 11, it is necessary to provide the same number of detection circuits as the number of phase shifters 15. However, with this configuration, if there are many phase shifters 15, a much smaller number of switches are provided than the number of phase shifters 15, so the number of detection circuits can also be reduced to the number of phase shifters 15. That is, the circuit size for fault detection can be reduced, and the circuit area can be reduced.

[0192] As explained with reference to Figures 8 and 13, in the distance measuring device 1 as a semiconductor device, the first phase shifter selection unit 36 ​​has a plurality of first phase shifter selection switches 38, and the second phase shifter selection unit 37 has a plurality of second phase shifter selection switches 40. The device includes a driver 39 provided for each predetermined number of first phase shifter selection switches 38, and a voltage monitoring unit provided in correspondence with the driver 39. The driver 39 may apply a feedback-controlled current to the phase shifter 15 based on the monitoring results from the voltage monitoring unit. This eliminates control variations for each driver 39 and improves distance measuring accuracy.

[0193] Furthermore, the effects described herein are merely illustrative and not limited to those described herein, and other effects may also occur.

[0194] Furthermore, the examples described above can be combined in any way, and it is possible to obtain the various effects and benefits described above even when using various combinations.

[0195] <7. The Technology> The technology can also be configured as follows: (1) A semiconductor device comprising: a plurality of light emitting units that emit probe light toward an object to be measured; a heater provided for each of the light emitting units that varies the emission angle of the probe light in the light emitting unit; and a heater selection unit that selects one heater to be controlled from the plurality of heaters, wherein the light emitting units are a plurality of optical antennas or a plurality of optical space couplers; the heater selection unit is provided with a first heater selection unit that selects one heater group from heater groups in which the plurality of heaters are divided into a plurality of groups, and a second heater selection unit that selects one heater from each heater group, wherein the heater to be controlled is a semiconductor device selected by the selection pattern of the first heater selection unit and the second heater selection unit. (2) The semiconductor device according to (1) above, wherein the first heater selection unit has a plurality of first heater selection switches, and the second heater selection unit has a plurality of second heater selection switches. (3) The semiconductor device according to (2) above, wherein the first heater selection unit has N first heater selection switches, the second heater selection unit has M second heater selection switches, N and M are both positive integers, and the product of N and M is equal to the number of light emitting units. (4) The semiconductor device according to (3) above, wherein the difference between N and M is the smallest possible combination of values ​​that N and M can take. (5) The semiconductor device according to any one of (2) to (4) above, wherein one of the first heater selection unit and the second heater selection unit is located on the positive electrode side of the heater and the other is located on the negative electrode side of the heater. (6) The semiconductor device according to (5) above, wherein each of the first heater selection switches and the second heater selection switches is provided with a detection circuit for detecting a fault. (7) A semiconductor device according to any one of (5) to (6) above, comprising: a driver provided for each predetermined number of first heater selection switches; and a voltage monitoring unit provided corresponding to the driver, wherein the driver applies a feedback-controlled current to the heater based on the monitoring results of the voltage monitoring unit.(8) A semiconductor device according to any one of (1) to (7) above, comprising a diode provided for each heater, wherein the cathode of the diode is connected to the input side of the heater. (9) A semiconductor device according to any one of (7) to (8) above, comprising an optical switch section that guides light to one of a plurality of light emission sections, wherein the optical switch section is configured in a tree structure with multiple stages of optical switch circuits. (10) A semiconductor device according to (9) above, wherein the optical switch circuit is configured to include a Mach-Zehnder interferometer or a microring resonator having a phase shifter. (11) The semiconductor device according to (10), further comprising a phase shifter selection unit that selects one of the phase shifters to be controlled from the phase shifters of the Mach-Zehnder interferometer or the microring resonator arranged in the same stage of the multi-stage tree structure, wherein the phase shifter selection unit comprises a first phase shifter selection unit that selects one phase shifter group from a group of phase shifter groups in which the phase shifters of the same stage that constitute the selection population are divided into multiple groups, and a second phase shifter selection unit that selects one phase shifter from each phase shifter group. (12) The semiconductor device according to (11), wherein the phase shifter selection unit having the first phase shifter selection unit and the second phase shifter selection unit is provided in a stage where the number of phase shifters arranged is greater than or equal to a predetermined number. (13) The optical switch section comprises a first optical switch section which includes a part of the plurality of optical switch circuits, and a second optical switch section which includes the remaining parts of the plurality of optical switch circuits, wherein the first optical switch section and the second optical switch section are each arranged in a tree structure of multiple levels, the first optical switch section is arranged on the substrate on one side with respect to the plurality of light emitting sections, and the second optical switch section is arranged on the substrate on the opposite side from the first optical switch section with respect to the plurality of light emitting sections, according to any of (9) to (12) above.(14) The semiconductor device according to (13), wherein the first optical switch unit is capable of directing light to an odd-numbered optical emitter among a plurality of optical emitters arranged in a row on the substrate, and the second optical switch unit is capable of directing light to an even-numbered optical emitter among a plurality of optical emitters arranged in a row on the substrate. (15) The semiconductor device according to any one of (1) to (14) above, wherein the optical emitter is a slow-light diffraction grating. (16) A semiconductor device comprising: an optical switch unit having a plurality of phase shifters and directing light to one of a plurality of optical antennas or a plurality of optical space couplers; and a phase shifter selection unit that selects a phase shifter to be controlled from the plurality of phase shifters, wherein the optical switch unit is configured such that the optical switch circuit is arranged in a plurality of stages tree structure, the optical switch circuit is configured to include a Mach-Zehnder interferometer or microring resonator having the phase shifter, the phase shifters having the Mach-Zehnder interferometer or microring resonator arranged in the same stage in the plurality of stages tree structure are the phase shifters of the same stage, the phase shifter selection unit is provided with a first phase shifter selection unit that selects one phase shifter group from a plurality of phase shifter groups in which the phase shifters of the same stage that constitute the selection population are divided into a plurality of groups, and a second phase shifter selection unit that selects one phase shifter from each phase shifter group, wherein the phase shifter to be controlled is selected by the selection pattern of the first phase shifter selection unit and the second phase shifter selection unit. (17) The semiconductor device according to (16), wherein each of the phase shifters is provided with a diode whose cathode is connected to the input side of the phase shifter. (18) The semiconductor device according to any one of (16) to (17), wherein the first phase shifter selection unit and the second phase shifter selection unit are arranged such that one is on the positive side of the phase shifter and the other is on the negative side of the phase shifter.(19) The semiconductor device according to (18), wherein the first phase shifter selection unit has a plurality of first phase shifter selection switches, the second phase shifter selection unit has a plurality of second phase shifter selection switches, and each of the first phase shifter selection switches and the second phase shifter selection switches is provided with a detection circuit for detecting a fault. (20) The semiconductor device according to any one of (18) to (19), wherein the first phase shifter selection unit has a plurality of first phase shifter selection switches, the second phase shifter selection unit has a plurality of second phase shifter selection switches, and comprises a driver provided for a predetermined number of the first phase shifter selection switches, and a voltage monitoring unit provided corresponding to the driver, wherein the driver applies a feedback-controlled current to the phase shifter based on the monitoring result by the voltage monitoring unit.

[0196] 1 Distance measuring device (semiconductor device) 7 Optical switch section 11 Optical switch circuit 11A Mach-Zehnder interferometer 15 Phase shifter 15G Phase shifter group 17 Slow light diffraction grating (light emission section) 18 Heater 18G Heater group 25 Heater selection section 26 First heater selection section 27 Second heater selection section 28 Diode 29 First heater selection switch 30 Driver 31 Second heater selection switch 32 Voltage monitoring section 34A First optical switch section 34B Second optical switch section 35 Phase shifter selection section 36 First phase shifter selection section 37 Second phase shifter selection section 38 First phase shifter selection switch 39 Driver 40 Second phase shifter selection switch 41 Diode 42 First detection circuit (detection circuit) 43 Second detection circuit (detection circuit) 44 First detection circuit (detection circuit) 45 Second detection circuit (detection circuit) Ang Emission angle Lp Probe light OB Object to be measured

Claims

1. A semiconductor device comprising: a plurality of light emitting units that emit probe light toward an object to be measured; a heater provided for each of the light emitting units that varies the emission angle of the probe light in the light emitting unit; and a heater selection unit that selects one heater to be controlled from the plurality of heaters, wherein the light emitting units are a plurality of optical antennas or a plurality of optical space couplers; the heater selection unit is provided with a first heater selection unit that selects one heater group from a plurality of heater groups in which the plurality of heaters are divided into a plurality of groups, and a second heater selection unit that selects one heater from each heater group, wherein the heater to be controlled is selected by the selection pattern of the first heater selection unit and the second heater selection unit.

2. The semiconductor device according to claim 1, wherein the first heater selection unit has a plurality of first heater selection switches, and the second heater selection unit has a plurality of second heater selection switches.

3. The semiconductor device according to claim 2, wherein the first heater selection unit has N first heater selection switches, the second heater selection unit has M second heater selection switches, N and M are both positive integers, and the product of N and M is equal to the number of light emitting units.

4. The semiconductor device according to claim 3, wherein the difference between N and M is the smallest possible combination of values ​​that N and M can take.

5. The semiconductor device according to claim 2, wherein one of the first heater selection unit and the second heater selection unit is located on the positive electrode side of the heater and the other is located on the negative electrode side of the heater.

6. The semiconductor device according to claim 5, further comprising a detection circuit for detecting a fault, provided for each of the first heater selection switch and the second heater selection switch.

7. The semiconductor device according to claim 5, comprising: a driver provided for each predetermined number of first heater selection switches; and a voltage monitoring unit provided corresponding to the driver, wherein the driver applies a feedback-controlled current to the heater based on the monitoring results from the voltage monitoring unit.

8. The semiconductor device according to claim 1, further comprising a diode provided for each heater, wherein the cathode of the diode is connected to the input side of the heater.

9. The semiconductor device according to claim 1, further comprising an optical switch section that guides light to one of the plurality of light-emitting sections, wherein the optical switch section is configured such that the optical switch circuits are arranged in a multi-stage tree structure.

10. The semiconductor device according to claim 9, wherein the optical switch circuit comprises a Mach-Zehnder interferometer or a microring resonator having a phase shifter.

11. The semiconductor device according to claim 10, comprising a phase shifter selection unit for selecting one of the phase shifters to be controlled from the phase shifters of the Mach-Zehnder interferometer or the microring resonator arranged in the same stage of the multi-stage tree structure, wherein the phase shifter selection unit comprises a first phase shifter selection unit for selecting one phase shifter group from a plurality of phase shifter groups in which the phase shifters of the same stage that constitute the selection population are divided into multiple groups, and a second phase shifter selection unit for selecting one phase shifter from each phase shifter group.

12. The semiconductor device according to claim 11, wherein, corresponding to each stage in the tree structure, the phase shifter selection unit having the first phase shifter selection unit and the second phase shifter selection unit is provided in a stage where the number of phase shifters to be arranged is a predetermined number or more.

13. The optical switch section comprises a first optical switch section which includes a portion of the plurality of optical switch circuits, and a second optical switch section which includes the remaining portion of the plurality of optical switch circuits, wherein the first optical switch section and the second optical switch section are each arranged in a tree structure of multiple levels, the first optical switch section is arranged on the substrate on one side with respect to the plurality of light emitting sections, and the second optical switch section is arranged on the substrate on the opposite side from the first optical switch section with respect to the plurality of light emitting sections, as described in claim 9.

14. The semiconductor device according to claim 13, wherein the first optical switch unit is capable of directing light to an odd-numbered optical emitter among a plurality of optical emitters arranged in a row on the substrate, and the second optical switch unit is capable of directing light to an even-numbered optical emitter among a plurality of optical emitters arranged in a row on the substrate.

15. The semiconductor device according to claim 1, wherein the light emitting portion is a slow light diffraction grating.

16. A semiconductor device comprising: an optical switch unit having a plurality of phase shifters and directing light to one of a plurality of optical antennas or a plurality of optical space couplers; and a phase shifter selection unit selecting a phase shifter to be controlled from the plurality of phase shifters, wherein the optical switch unit is configured such that the optical switch circuit is arranged in a plurality of stages tree structure, the optical switch circuit is configured to include a Mach-Zehnder interferometer or microring resonator having the phase shifter, the phase shifters having the Mach-Zehnder interferometer or microring resonator arranged in the same stage of the plurality of stages tree structure are the phase shifters of the same stage, the phase shifter selection unit is provided with a first phase shifter selection unit that selects one phase shifter group from a plurality of phase shifter groups in which the phase shifters of the same stage that constitute the selection population are divided into a plurality of groups, and a second phase shifter selection unit that selects one phase shifter from each phase shifter group, wherein the phase shifter to be controlled is selected by the selection pattern of the first phase shifter selection unit and the second phase shifter selection unit.

17. The semiconductor device according to claim 16, wherein each of the phase shifters is further provided with a diode whose cathode is connected to the input side of the phase shifter.

18. The semiconductor device according to claim 16, wherein one of the first phase shifter selection unit and the second phase shifter selection unit is located on the positive electrode side of the phase shifter and the other is located on the negative electrode side of the phase shifter.

19. The semiconductor device according to claim 18, wherein the first phase shifter selection unit has a plurality of first phase shifter selection switches, the second phase shifter selection unit has a plurality of second phase shifter selection switches, and each of the first phase shifter selection switches and the second phase shifter selection switches is provided with a detection circuit for detecting a fault.

20. The semiconductor device according to claim 18, wherein the first phase shifter selection unit has a plurality of first phase shifter selection switches, the second phase shifter selection unit has a plurality of second phase shifter selection switches, a driver provided for each predetermined number of the first phase shifter selection switches, and a voltage monitoring unit provided corresponding to the driver, the driver applies a feedback-controlled current to the phase shifter based on the monitoring results of the voltage monitoring unit.

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