Optical switch and method of operating optical switch

Abstract

To switch an optical switch to the closed state by applying a high voltage, and generate a high voltage switch signal from the optical switch.SOLUTION: An optical switch 10 includes a semiconductor substrate 11, a pair of electrodes 12A, 12B placed on the semiconductor substrate, a pulsed power supply 13 that applies a voltage between the electrodes, and a trigger light source 14 that generates trigger light 1. The semiconductor substrate is made of a semi-insulating semiconductor and equipped with a trigger light introduction surface 16 that introduces the trigger light into the interior. A carrier generation region 17 is provided inside the electrode where carriers are generated as the trigger light passes and the electrical resistance value decreases. The optical switch further includes voltage measurement means 15M that measures the voltage applied to the electrodes, and voltage peak detection means 15N that detects the peak of the applied voltage measured by the voltage measurement means and outputs a trigger signal 2 for generating the trigger light 1 to the trigger light source 14 at the timing of the peak.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] An embodiment of the present invention relates to an optical switch that opens and closes a circuit using light, and a method of operating the optical switch. [Background technology]

[0002] Optical switches, which open and close circuits using light rather than electrical signals, are used in a variety of applications, such as for faster response than electrical control, noise reduction, and electrical isolation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-209269 A [Patent Document 2] JP 2005-191074 A [Patent Document 3] Japanese Utility Model Application Publication No. 58-166627 [Patent Document 4] Japanese Patent Application Publication No. 7-22603 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 discloses an optical switch that uses the photoconductive effect, in which electrons in the valence band are excited to the conduction band when light with a wavelength shorter than the bandgap wavelength of a semi-insulating semiconductor is irradiated, and carriers are injected, lowering the electrical resistance. By using high-speed pulsed laser light or the like as trigger light, this optical switch can perform a closing operation faster than normal switching elements controlled by electrical signals, and can also be used at high voltages because the substrate made of a semi-insulating semiconductor has a high withstand voltage.

[0005] FIG. 14 shows the configuration of a typical conventional optical switch. The optical switch 100 has a structure in which a pair of electrodes 101 is disposed on a semiconductor substrate 102. The semiconductor substrate 102 is made of a semi-insulating semiconductor, and a carrier generation region 103 is provided in the region sandwiched between the pair of electrodes 101. The carrier generation region 103 is excited by light to excite electrons in the valence band of the semiconductor substrate 102 to the conduction band, generating carriers and lowering the electrical resistance value. Furthermore, trigger light 104 is incident on the semiconductor substrate 102 through a trigger light introduction surface 105. The optical switch 100 is an insulator in a normal state, but carriers are generated by absorbing light of a wavelength corresponding to the band gap wavelength of the semiconductor substrate 102 into the carrier generation region 105, and a current from a power source 106 flows between the electrodes 101.

[0006] On the other hand, the semi-insulating semiconductor of the semiconductor substrate 102 ideally behaves as an insulator, but in reality, its electrical resistance value decreases due to a high electric field. For this reason, in the optical switch 100, the voltage applied to the electrode 101 also decreases due to voltage division with the load 107 connected to the optical switch 100, and the voltage when the optical switch 100 is switched and the voltage of the switch signal generated by the optical switch 100 are limited. In other words, in the optical switch 100 that controls an electrical signal using photoconduction, when the voltage applied to the electrode 101 increases, the electrical resistance value of the semiconductor substrate 102 decreases, and the voltage applied to the electrode 101 also decreases due to voltage division with the load 107, which is a problem.

[0007] The embodiments of the present invention have been made in consideration of the above-mentioned circumstances, and have an object to provide an optical switch and an operating method of an optical switch that can realize switching of the optical switch to a closed state by applying a high voltage and can generate a high-voltage switch signal from the optical switch. [Means for solving the problem]

[0008] An optical switch in an embodiment of the present invention comprises a semiconductor substrate, a pair of electrodes disposed on the semiconductor substrate, a power source connected to the electrodes and applying a voltage between the electrodes, and a trigger light source that generates trigger light, the semiconductor substrate being made of a semi-insulating semiconductor and having a trigger light introduction surface on one side for introducing the trigger light into the interior, and a carrier generation region being provided inside the pair of electrodes in which carriers are generated as the trigger light passes through, thereby reducing the electrical resistance value, and the optical switch is characterized in that it further comprises trigger signal output means for outputting a trigger signal for generating the trigger light to the trigger light source when the voltage applied to the electrodes reaches or nears its peak.

[0009] A method of operating an optical switch in an embodiment of the present invention includes a semiconductor substrate, a pair of electrodes disposed on the semiconductor substrate, a power source connected to the electrodes and applying a voltage between the electrodes, and a trigger light source that generates trigger light, wherein the semiconductor substrate is made of a semi-insulating semiconductor and has a trigger light introduction surface on one side for introducing the trigger light into the interior, and a carrier generation region is provided inside the pair of electrodes in which carriers are generated by the passage of the trigger light and an electrical resistance value is reduced, wherein a trigger signal output means outputs a trigger signal for generating the trigger light to the trigger light source when the voltage applied to the electrodes reaches or nears its peak. Effect of the Invention

[0010] According to the embodiment of the present invention, the optical switch can be switched to the closed state by applying a high voltage, and a high voltage switch signal can be generated from the optical switch. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a plan view showing an optical switch according to a first embodiment. [Diagram 2]FIG. 2 is a block diagram including a cross-sectional view taken along line II-II in FIG. [Diagram 3] 3 is a graph showing voltages applied to the electrodes of FIGS. 1 and 2, etc.; [Figure 4] 3 is a timing chart for the optical switch shown in FIGS. 1 and 2. [Diagram 5] FIG. 11 is a block diagram showing an optical switch according to a second embodiment. [Figure 6] 6 is a timing chart for the optical switch shown in FIG. 5 . [Figure 7] 13 is a timing chart in the optical switch according to the fourth embodiment. [Figure 8] FIG. 13 is a block diagram showing an optical switch according to a fifth embodiment. [Figure 9] 9 is a timing chart for the optical switch shown in FIG. 8 . [Figure 10] FIG. 13 is a block diagram showing an optical switch according to a sixth embodiment. [Figure 11] 11 is a timing chart for the optical switch shown in FIG. 10. [Figure 12] FIG. 13 is a block diagram showing an optical switch according to a seventh embodiment. [Figure 13] 13 is a timing chart for the optical switch shown in FIG. 12. [Figure 14] 14A and 14B are block diagrams showing a conventional optical switch, in which (A) is a plan view thereof and (B) is a cross-sectional view taken along line XIVB-XIVB of FIG. 14A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. [A] First embodiment (FIGS. 1 to 4) Fig. 1 is a plan view showing an optical switch according to a first embodiment, and Fig. 2 is a block diagram including a cross-sectional view taken along line II-II in Fig. 1.

[0013] The optical switch 10 shown in Figures 1 and 2 is a switch that opens and closes a circuit using light (trigger light 1), and is configured to include a semiconductor substrate 11, a pair or multiple pairs (for example, a pair) of electrodes 12A, 12B that are provided on the front and back surfaces of the semiconductor substrate 11, a pulse power supply 13 that is connected to these electrodes 12A, 12B and applies a pulse voltage between these electrodes 12A, 12B as an applied voltage, a trigger light source 14 that generates the trigger light 1, and trigger signal output means 15 that outputs a trigger signal 2 to the trigger light source 14 to generate the trigger light 1.

[0014] The electrodes 12A and 12B are made of an electrical conductor such as Au, Ni, Cr, Ti, Mo, W, Al, Ag, Cu, Pd, Pt, or ITO (Indium-Tin Oxide). The electrodes 12A and 12B may be made by laminating the above conductors. The electrodes 12A and 12B are preferably rectangular with a diameter of Φ0.5 mm to Φ20 mm or a side of 0.5 mm to 20 mm. The electrodes 12A and 12B are preferably thicker than 10 nm to 1 μm.

[0015] Semiconductor substrate 11 is made of a semi-insulating semiconductor such as Si, GaAs, 4H-SiC, 6H-SiC, GaN, or diamond. Semiconductor substrate 11 preferably has a side length of 1 mm to 50 mm and a thickness of 0.1 mm to 10 mm. Semiconductor substrate 11 has trigger light introduction surface 16 and carrier generation region 17. Carrier generation region 17 may be formed so as to be exposed on the surface of semiconductor substrate 11.

[0016] The trigger light introduction surface 16 is formed on one side of the semiconductor substrate 11, and introduces the trigger light 1 into the inside of the semiconductor substrate 11. The carrier generation region 17 is provided inside the semiconductor substrate 11, corresponding to the pair of electrodes 12A and 12B, that is, in a region between the electrodes 12A and 12B inside the semiconductor substrate 11. In the carrier generation region 17, electrons in the valence band are excited to the conduction band when the trigger light 1 passes through, generating carriers, and the electrical resistance value decreases. When the carrier generation region 17 is formed exposed on the surface of the semiconductor substrate 11, the trigger light 1 may be irradiated directly onto the carrier generation region 17 without passing through the trigger light introduction surface 16.

[0017] Optical switch 10 is normally in an electrically insulated state. However, when trigger light 1 having a wavelength corresponding to the bandgap wavelength of semiconductor substrate 11 is absorbed by carrier generation region 17, carriers are generated, optical switch 10 closes, and a current flows between electrodes 12A and 12B.

[0018] The pulsed power supply 13 is connected to the electrodes 12A and 12B of the optical switch 10 via a load 18. The pulsed voltage generated by the pulsed power supply 13 may be positive or negative, and the waveform may be Gaussian-like, rectangular, or free waveform. The rise time of the pulsed voltage is set to, for example, 1 ms. When the optical switch 10 is closed, a current flows between the electrodes 12A and 12B via the semiconductor substrate 11 due to the voltage applied between the pair of electrodes 12A and 12B by the pulsed power supply 13.

[0019] As described above, the trigger light 1 generated by the trigger light source 14 is incident on the trigger light introduction surface 16 of the semiconductor substrate 11 and passes through the carrier generation region 17. This trigger light 1 is preferably a laser light including a pulsed laser light. Furthermore, the wavelength of this trigger light 1 is set to be longer than one time and not more than two times the band gap wavelength of the semi-insulating semiconductor constituting the semiconductor substrate 11.

[0020] For example, the band gap wavelengths of Si, GaAs, SiC, GaN, and diamond constituting the semiconductor substrate 11 are 1117 nm, 867 nm, 384 nm, 364 nm, and 226 nm, respectively. Therefore, the laser light as the trigger light 1 is preferably an Er:YAG laser when the semiconductor substrate 11 is made of Si, and is preferably an Er:YAG laser, an Nd:YAG laser, an Nd:YVO4 laser, an Yb:YAG laser, or an Yb fiber laser when the semiconductor substrate 11 is made of GaAs, and is preferably a second harmonic of the Nd:YAG laser, an Nd:YVO4 laser, an Yb:YAG laser, or an Yb fiber laser when the semiconductor substrate 11 is made of SiC or GaN, and is preferably a third harmonic of the Nd:YAG laser, an Nd:YVO4 laser, an Yb:YAG laser, or an Yb fiber laser when the semiconductor substrate 11 is made of diamond. The trigger light 1 may also be light from a flash lamp, a semiconductor laser corresponding to each wavelength, or light from a light emitting diode, etc.

[0021] Furthermore, the trigger light 1 may be set to a wavelength equal to or less than the band gap of the semi-insulating semiconductor constituting the semiconductor substrate 11. In this case, the laser light as the trigger light 1 is preferably an Nd:YAG laser, an Nd:YVO4 laser, an Yb:YAG laser, or an Yb fiber laser when the semiconductor substrate 11 is made of Si, is preferably a second harmonic of an Er:YAG laser, an Nd:YAG laser, an Nd:YVO4 laser, an Yb:YAG laser, or an Yb fiber laser when the semiconductor substrate 11 is made of GaAs, is preferably a third harmonic of an Nd:YAG laser, an Nd:YVO4 laser, an Yb:YAG laser, or an Yb fiber laser when the semiconductor substrate 11 is made of SiC or GaN, and is preferably an ArF excimer laser when the semiconductor substrate 11 is made of diamond. The trigger light 1 may also be light from a flash lamp, a semiconductor laser corresponding to each wavelength, or light from a light-emitting diode or the like.

[0022] The trigger light 1 may be set to a wavelength longer than twice and equal to or less than three times the band gap wavelength of the semi-insulating semiconductor constituting the semiconductor substrate 11. For example, the laser light as the trigger light 1 is preferably an Nd:YAG laser, an Nd:YVO4 laser, an Yb:YAG laser, or an Yb fiber laser when the semiconductor substrate 11 is made of SiC or GaN, and is preferably the second harmonic of an Nd:YAG laser, an Nd:YVO4 laser, an Yb:YAG laser, or an Yb fiber laser when the semiconductor substrate 11 is made of diamond. In this case, the trigger light 1 may be light from a flash lamp, a semiconductor laser corresponding to each wavelength, or light from a light emitting diode or the like.

[0023] The trigger signal output means 15 outputs a trigger signal 2 for generating trigger light 1 to the trigger light source 14 at the timing when the applied voltage applied to the electrodes 12A, 12B reaches its peak, and is configured with a voltage measurement means 15M and a voltage peak detection means 15N. The voltage measurement means 15M measures the applied voltage applied to the electrodes 12A, 12B from the pulse power supply 13, and is preferably a voltage probe, a high voltage probe, an insulating probe, or the like. The voltage peak detection means 15N is connected to the voltage measurement means 15M, detects the peak of the applied voltage measured by this voltage measurement means 15M, and outputs a trigger signal 2 to the trigger light source 14 at the timing when this peak is detected. For example, a differential circuit or the like is used as the voltage peak detection means 15N.

[0024] An example of the voltage applied to the electrodes 12A and 12B when the pulse voltage (pulse power supply set voltage) from the pulse power supply 13 is sufficiently high and its rise speed is sufficiently fast (for example, the rise time is 1 ms or less) is shown in Fig. 3. In Fig. 3, the pulse voltage from the pulse power supply 13 is a square wave, whereas the voltage actually applied to the electrodes 12A and 12B differs from the pulse voltage from the pulse power supply 13 in that a peak occurs.

[0025] This is because the response time of the electrical resistance value drop of the semiconductor substrate 11 is slow, for example, about 50 μs to 1 ms. Therefore, if the rise time of the pulse voltage supplied from the pulse power source 13 is approximately the same as or shorter (for example, 1 ms or less) than the response time of the electrical resistance value drop of the semiconductor substrate 11, the drop in the electrical resistance value of the semiconductor substrate 11 is not significant immediately after the voltage application to the electrodes 12A and 12B starts, and during that short time, the voltage division between the semiconductor substrate 11 and the load 18 is suppressed and the voltage applied to the electrodes 12A and 12B increases. Then, as time passes, the drop in the electrical resistance value of the semiconductor substrate 11 becomes significant, and a peak occurs in the voltage applied to the electrodes 12A and 12B, and thereafter, the voltage applied to the electrodes 12A and 12B drops to a constant voltage value.

[0026] 4 shows a timing chart from application of the pulse voltage to generation of the switch signal 3 when the rise time of the pulse voltage from the pulse power source 13 is sufficiently short, 1 ms or less, and the pulse voltage is sufficiently high. In this case, as described above, the voltage actually applied to the electrodes 12A and 12B peaks at a value close to the pulse power source setting voltage of the pulse power source 13, and then decreases to a constant value over the response time (50 μs to 1 ms) of the decrease in the electrical resistance value of the semiconductor substrate 11. The voltage measurement means 15M measures the voltage applied to the electrodes 12A and 12B, and transmits the measured voltage to the voltage peak detection means 15N. The voltage peak detection means 15N outputs a trigger signal 2 to the trigger light source 14 at the timing when the applied voltage peaks, and the trigger light source 14 generates the trigger light 1.

[0027] Next, the operation of the optical switch 10 configured as described above will be described with reference to FIGS. In a normal state, the optical switch 10 is in an open state. When a pulse voltage is applied between the pair of electrodes 12A, 12B by the pulse power supply 13, this applied voltage is measured by the voltage measurement means 15M and sent to the voltage peak detection means 15N. The voltage peak detection means 15N detects the peak of the applied voltage measured by the voltage measurement means 15M, and outputs a trigger signal 2 to the trigger light source 14 at the timing of this peak. As a result, trigger light 1 is generated from the trigger light source 14 and irradiated onto the semiconductor substrate 11.

[0028] This trigger light 1 passes through trigger light introducing surface 16 of semiconductor substrate 11 and is absorbed in carrier generation region 17 of semiconductor substrate 11, and carriers are generated in carrier generation region 17. This reduces the electrical resistance value of carrier generation region 17, causing optical switch 10 to close. That is, optical switch 10 closes when the voltage applied to electrodes 12A and 12B reaches its peak value, and outputs the peak voltage to load 18 as switch signal 3.

[0029] As configured as above, the first embodiment provides the following effect (1). (1) The voltage measurement means 15M measures the voltage applied to the electrodes 12A and 12B, and the voltage peak detection means 15N outputs a trigger signal 2 to the trigger light source 14 at the timing when the measured applied voltage reaches its peak. As a result, trigger light 1 is introduced from the trigger light source 14 to the semiconductor substrate 11, the electrical resistance value of the carrier generation region 17 of the semiconductor substrate 11 decreases, the optical switch 10 switches to the closed state, and the optical switch 10 generates a switch signal 3. As a result, the optical switch 10 can be switched to the closed state at the high voltage of the peak of the applied voltage, and a high-voltage switch signal 3 can be generated from the optical switch 10.

[0030] [B] Second embodiment (FIGS. 5 and 6) 5 is a block diagram showing an optical switch according to a second embodiment. In the second embodiment, the same parts as in the first embodiment are denoted by the same reference numerals as in the first embodiment, and the description thereof will be simplified or omitted.

[0031] The optical switch 20 of the second embodiment differs from the first embodiment in that a sine wave power supply 21 that generates a sine wave voltage (sine wave power supply set voltage in FIG. 6) is installed instead of the pulse power supply 13 of the first embodiment. This sine wave power supply 21 is a power supply that generates a pure sine wave voltage, but may also be a modified sine wave power supply that generates, for example, a stepped modified sine wave voltage.

[0032] A sine wave voltage is applied to the electrodes 12A and 12B by the sine wave power supply 21. Here, as in the first embodiment, the electrical resistance value of the semiconductor substrate 11 decreases according to the sine wave voltage, and the voltage applied to the electrodes 12A and 12B also decreases due to voltage division with the load 18. On the other hand, when the output frequency of the sine wave voltage is sufficiently high, the voltage is applied to the electrodes 12A and 12B before the decrease in the electrical resistance value of the semiconductor substrate 11 becomes significant, so that the voltage applied to the electrodes 12A and 12B has a peak at a position different from the peak of the sine wave power supply 21 as shown in FIG. 6, as in the first embodiment. At this time, the frequency of the sine wave voltage needs to have a rise time equal to or shorter than the response time (50 μs to 1 ms) of the decrease in the electrical resistance value of the semiconductor substrate 11, and is, for example, 250 Hz or more.

[0033] As in the first embodiment, voltage measurement means 15M measures the voltage applied to electrodes 12A and 12B, and transmits the measured voltage to voltage peak detection means 15N. As shown in Fig. 6, voltage peak detection means 15N outputs trigger signal 2 to trigger light source 14 at the timing when the applied voltage reaches its peak, and trigger light source 14, upon receiving trigger signal 2, generates trigger light 1. Trigger light 1 passes through trigger light introduction surface 16 of semiconductor substrate 11 and is absorbed in carrier generation region 17, and carriers are generated in carrier generation region 17. This reduces the electrical resistance value of carrier generation region 17, causing optical switch 20 to close.

[0034] As configured as described above, in the second embodiment as well, the optical switch 20 is closed at the timing when the voltage applied to the electrodes 12A, 12B reaches its peak, thereby achieving the same effect as effect (1) of the first embodiment.

[0035] [C] Third embodiment (FIGS. 2, 3, and 5) In the third embodiment, the same parts as those in the first and FIG. 2 embodiments are denoted by the same reference numerals as those in the first embodiment, and the description thereof will be simplified or omitted.

[0036] An optical switch 30 (FIG. 2) of the third embodiment differs from the first embodiment in that a pulsed power supply 31 is provided instead of the pulsed power supply 13 of the first embodiment. When no pulsed voltage is being generated, this pulsed power supply 31 always outputs a bias voltage (FIG. 3) that has the same polarity as the pulsed voltage and is a constant voltage that is lower than the pulsed voltage and is not 0 V.

[0037] Furthermore, the optical switch 30 of the third embodiment may be provided with a sine wave power supply 32 that outputs a sine wave voltage having a positive or negative bias voltage, instead of the sine wave power supply 21 (FIG. 5) of the second embodiment. The sine wave power supply 32 may be a modified sine wave power supply that outputs a modified sine wave voltage having a positive or negative bias voltage. However, in the following description of the third embodiment, the pulse power supply 31 (FIG. 2) will be described.

[0038] As described above, the pulse power supply 31 always outputs a positive or negative bias voltage. This bias voltage is lower than the voltage actually applied to the electrodes 12A and 12B of the optical switch 30, and is a voltage that does not significantly reduce the electrical resistance of the semiconductor substrate 11 when the trigger light 1 is not irradiated, for example, a voltage that makes the average electric field between the electrodes 12A and 12B 5MV / m or less.

[0039] In the normal state, optical switch 30 is in the open state, and the voltage applied to electrodes 12A, 12B is a bias voltage. Therefore, the electrical resistance value of semiconductor substrate 11 is sufficiently high, and no significant reduction in the voltage applied to electrodes 12A, 12B due to the voltage division between semiconductor substrate 11 and load 18 occurs.

[0040] When the pulse power supply 31 outputs a pulse voltage, this pulse voltage has the same polarity as the bias voltage previously output, and has a rise time equal to or shorter than the response time of the drop in the electrical resistance value of the semiconductor substrate 11 (for example, 1 ms or less). Therefore, the voltage applied to the electrodes 12A and 12B by this pulse voltage becomes larger than the voltage that causes a drop in the electrical resistance value of the semiconductor substrate 11, but at first, since the rise time of the applied voltage is shorter than the response time of the drop in the electrical resistance value, a significant drop in the electrical resistance value of the semiconductor substrate 11 does not occur. As time gradually passes, the effect of the drop in the electrical resistance value of the semiconductor substrate 11 becomes significant, and a peak occurs in the applied voltage applied to the electrodes 12A and 12B, and finally the voltage drops to a specific constant voltage value.

[0041] In the third embodiment as well, voltage measurement means 15M measures the voltage applied to electrodes 12A, 12B, and transmits this measured voltage to voltage peak detection means 15N. When the applied voltage reaches its peak, voltage peak detection means 15N outputs trigger signal 2 to trigger light source 14, which then generates trigger light 1. Trigger light 1 passes through trigger light introducing surface 16 of semiconductor substrate 11 and is absorbed in carrier generation region 17 of semiconductor substrate 11, and carriers are generated in carrier generation region 17. This reduces the electrical resistance of carrier generation region 17, causing optical switch 30 to close.

[0042] As configured as above, the third embodiment also achieves the same effect as the effect (1) of the first embodiment, and also achieves the following effect (2). (2) When the pulsed power supply 31 is not generating a pulsed voltage, the pulsed power supply 31 always outputs a bias voltage that has the same polarity as the pulsed voltage but is lower than the pulsed voltage. Therefore, when a pulsed voltage is generated, the pulsed voltage can be caused to rise quickly.

[0043] [D] Fourth embodiment (Figs. 2 and 7) 7 is a timing chart of the optical switch according to the fourth embodiment. In the fourth embodiment, the same parts as in the first embodiment are denoted by the same reference numerals as in the first embodiment, and the description thereof will be simplified or omitted.

[0044] An optical switch 40 (FIG. 2) of the fourth embodiment differs from the first embodiment in that it includes a voltage peak detection means 41. This voltage peak detection means 41 detects the peak of the voltage applied to the electrodes 12A, 12B measured by the voltage measurement means 15M, and outputs a trigger signal 2 to the trigger light source 14 at a timing near this peak (that is, at a timing when a predetermined delay time has elapsed since the detection of the peak, as shown in FIG. 7). Here, the above-mentioned voltage measurement means 15M and voltage peak detection means 41 constitute a trigger signal output means 42.

[0045] As described above, when a predetermined delay time has elapsed since voltage peak detection means 41 detected the peak of the voltage applied to electrodes 12A and 12B, trigger signal 2 is output to trigger light source 14, trigger light source 14 irradiates semiconductor substrate 11 of optical switch 40 with trigger light 1, optical switch 40 closes and generates switch signal 3. This makes it possible to adjust the timing of the closing switching operation of optical switch 40 to a timing delayed by a predetermined time from the peak of the applied voltage.

[0046] As configured as above, the fourth embodiment achieves the following effect (3) in addition to the effect (1) of the first embodiment.

[0047] (3) The voltage peak detection means 41 is configured to output the trigger signal 2 to the trigger light source 14 at a timing when a predetermined delay time has elapsed since the detection of the peak of the voltage applied to the electrodes 12A, 12B. Therefore, the value of the voltage (the voltage applied to the electrodes 12A, 12B) when the optical switch 40 is switched to the closed state can be adjusted to a desired voltage value, and the switch signal 3 output when the optical switch 40 is closed can be adjusted to a desired voltage value.

[0048] Although the power supply has been described as being a pulse power supply 13, it may be the sine wave power supply 21 (including a modified sine wave power supply) of the second embodiment, or may be the pulse power supply 31 or sine wave power supply 32 (including a modified sine wave power supply) of the third embodiment that generates a bias voltage.

[0049] [E] Fifth embodiment (FIGS. 8 and 9) 8 is a block diagram showing an optical switch according to a fifth embodiment. In the fifth embodiment, the same parts as in the first embodiment are denoted by the same reference numerals as in the first embodiment, and the description thereof will be simplified or omitted.

[0050] The optical switch 50 of the fifth embodiment differs from the first embodiment in that it includes a differentiation circuit 51. After the voltage applied to the electrodes 12A and 12B from the pulse power supply 13 is measured by the voltage measurement means 15M, the differentiation circuit 51 differentiates the measured voltage to generate a differentiation signal. Here, the voltage measurement means 15M and differentiation circuit 51 constitute the trigger signal output means 52.

[0051] 9, the pulsed power supply 13 outputs a gate signal 5 of an arbitrary time width to the differentiation circuit 51 after a predetermined time has elapsed since the start of application of the pulsed voltage. Then, while receiving the gate signal 5, the differentiation circuit 51 outputs a trigger signal 2 to the trigger light source 14 at the timing when the differentiated signal first crosses the trigger threshold (the rising or falling voltage of the differentiated signal, for example, the falling voltage). Here, the predetermined time when the pulsed power supply 13 outputs the gate signal 5 and the time width of the gate signal 5 may be at most about 1 ms, which is the response time of the decrease in the electrical resistance value in the semiconductor substrate 11, and can be adjusted within the range of 0 ms to 1 ms.

[0052] In the optical switch 50 of the fifth embodiment, similarly to the first embodiment, the pulse power supply 13 applies a voltage to the electrodes 12A and 12B. Furthermore, the pulse power supply 13 outputs a gate signal 5 of an arbitrary duration to the differentiation circuit 51 after an arbitrary time has elapsed since the start of application of the pulse voltage.

[0053] The differentiating circuit 51 differentiates the applied voltage from the voltage measuring means 15M, and when the differentiated signal becomes any rising or falling voltage (e.g., a falling voltage) that intersects with the trigger threshold, outputs a trigger signal 2 to the trigger light source 14. When the trigger light source 14 irradiates the semiconductor substrate 11 with trigger light 1, the optical switch 50 closes and a switch signal 3 is generated.

[0054] As described above, the output of trigger signal 2 by differentiation circuit 51 is limited by gate signal 5. Since the start of gate signal 5 is set to a predetermined time after the start of application of the pulse voltage, trigger signal 2 is not output at 0 seconds after the start of the pulse voltage or when application of the pulse voltage ends. At the position where the voltage applied to electrodes 12A and 12B of optical switch 50 reaches its peak, the differentiation signal falls to 0V, and differentiation circuit 51 can output trigger signal 2 before the peak of the applied voltage by shifting the set voltage for outputting trigger signal 2 to the + side, or after the peak of the applied voltage by shifting it to the - side.

[0055] As configured as above, the fifth embodiment provides the following effect (4) in addition to the effect (1) of the first embodiment.

[0056] (4) The differentiating circuit 51 differentiates the applied voltage measured by the voltage measuring means 15M to generate a differentiated signal, the pulsed power supply 13 outputs a gate signal 5 of an arbitrary time width to the differentiating circuit 51 after a predetermined time has elapsed since the start of application of the pulsed voltage, and the differentiating circuit 51 outputs a trigger signal 2 to the trigger light source 14 at the timing when the differentiated signal first crosses the trigger threshold while receiving the gate signal 5. Therefore, the optical switch 50 can be switched to close at any timing before or after the time when the applied voltage to the electrodes 12A and 12B reaches its peak, and the switch signal 3 can be generated from the optical switch 50. As a result, the value of the voltage (applied voltage to the electrodes 12A and 12B) when the optical switch 50 is switched to close can be adjusted to a desired voltage value, and the switch signal 3 outputted when the optical switch 50 is closed can be adjusted to a desired voltage value.

[0057] Although the power supply is the pulse power supply 13 in the above embodiment, the power supply may be the pulse power supply 31 (FIG. 2) of the third embodiment that generates a bias voltage.

[0058] [F] Sixth embodiment (FIGS. 10 and 11) 10 is a block diagram showing an optical switch according to a sixth embodiment. In the sixth embodiment, the same parts as those in the first and second embodiments are denoted by the same reference numerals as those in the first and second embodiments, and the description thereof will be simplified or omitted.

[0059] The optical switch 60 of the sixth embodiment differs from the second embodiment in that the voltage measuring means 15M is omitted and a trigger circuit 61 is provided instead of the voltage peak detecting means 15N. This trigger circuit 61 inputs a waveform signal 6 of a sine wave voltage (sine wave power supply set voltage) from the sine wave power supply 21 or a waveform signal of a modified sine wave voltage from a modified sine wave power supply, and outputs a trigger signal 2 to the trigger light source 14 at the timing when the sine wave voltage or the modified sine wave voltage becomes an arbitrary rising voltage or falling voltage. Here, the above-mentioned trigger circuit 61 constitutes a trigger signal output means 62.

[0060] Hereinafter, a case where the sine wave power supply 21 generates a pure sine wave voltage will be described. A sine wave voltage is applied to the electrodes 12A and 12B from the sine wave power supply 21. As in the second embodiment, the electrical resistance value of the semiconductor substrate 11 decreases according to the applied sine wave voltage, and the applied voltage to the electrodes 12A and 12B also decreases due to voltage division with the load 18. On the other hand, when the output frequency of the sine wave voltage is sufficiently high, the voltage is applied before the decrease in the electrical resistance value of the semiconductor substrate 11 becomes significant, so that the applied voltage has a peak at a position different from the peak of the sine wave voltage, as shown in FIG. 11, as in the second embodiment. In this case, the frequency of the sine wave voltage needs to have a rise time equal to or shorter than the response time (50 μs to 1 ms) of the decrease in the electrical resistance value of the semiconductor substrate 11, and is, for example, 250 Hz or less.

[0061] Since the sine wave voltage from the sine wave power supply 21 is periodic, the voltage applied to the electrodes 12A, 12B is also periodic, and the period of the applied voltage is the same as that of the sine wave voltage. Therefore, the trigger circuit 61 specifies an arbitrary rising voltage or falling voltage (e.g., a rising voltage) at which the sine wave voltage crosses the trigger threshold, and outputs a trigger signal 2 to the trigger light source 14 at the timing when the voltage applied to the electrodes 12A, 12B reaches an arbitrary wave height (e.g., a peak).

[0062] As configured as above, the sixth embodiment also provides the following effect (5) in addition to the effect (1) of the first embodiment.

[0063] (5) The trigger circuit 61 is configured to input a waveform signal 6 of a sine wave voltage from the sine wave power supply 21, and output a trigger signal 2 to the trigger light source 14 at the timing when this sine wave voltage becomes an arbitrary rising voltage or falling voltage. Therefore, the optical switch 60 can be switched to a closed state at any timing before or after the time when the voltage applied to the electrodes 12A and 12B reaches its peak, and the switch signal 3 can be generated from the optical switch 60. As a result, the value of the voltage (the voltage applied to the electrodes 12A and 12B) when the optical switch 60 is switched to a closed state can be adjusted to a desired voltage value, and the switch signal 3 output when the optical switch 60 is closed can be adjusted to a desired voltage value.

[0064] Although the power supply has been described as being the sine wave power supply 21, it may be the sine wave power supply 32 (FIG. 5) of the third embodiment which outputs a sine wave voltage having a bias voltage or a modified sine wave voltage.

[0065] [G] Seventh embodiment (FIGS. 12 and 13) 12 is a block diagram showing an optical switch according to a seventh embodiment. In the seventh embodiment, the same parts as those in the first and second embodiments are denoted by the same reference numerals as those in the first and second embodiments, and the description thereof will be simplified or omitted.

[0066] The optical switch 70 of the seventh embodiment differs from the second embodiment in that the voltage measuring means 15M is omitted, and a delay circuit 71 and a trigger circuit 72 are provided instead of the voltage peak detecting means 15N. The delay circuit 71 inputs the waveform signal 6 of the sine wave voltage from the sine wave power supply 21 or the waveform signal of the modified sine wave voltage from the modified sine wave power supply, and gives a predetermined time delay to the sine wave voltage or the modified sine wave voltage. The trigger circuit 72 outputs a trigger signal 2 to the trigger light source 14 at the timing when the delayed sine wave voltage or the delayed modified sine wave voltage from the delay circuit 71 becomes an arbitrary rising voltage or falling voltage. Here, the above-mentioned delay circuit 71 and trigger circuit 72 constitute a trigger signal output means 73.

[0067] Hereinafter, a case where the sine wave power supply 21 generates a pure sine wave voltage will be described. A sine wave voltage is applied to the electrodes 12A and 12B from the sine wave power supply 21. As in the second embodiment, the electrical resistance value of the semiconductor substrate 11 decreases according to the applied sine wave voltage, and the applied voltage to the electrodes 12A and 12B also decreases due to voltage division with the load 18. On the other hand, when the output frequency of the sine wave voltage is sufficiently high, the voltage is applied before the decrease in the electrical resistance value of the semiconductor substrate 11 becomes significant, so that the applied voltage has a peak at a position different from that of the sine wave voltage as shown in FIG. 13, as in the second embodiment.

[0068] Since the sine wave voltage from the sine wave power supply 21 is periodic, the voltage applied to the electrodes 12A, 12B is also periodic, and the period of the applied voltage is the same as that of the sine wave voltage. Therefore, the delay circuit 71 sets an arbitrary delay time, and the trigger circuit 72 specifies an arbitrary rising or falling voltage (e.g., a rising voltage) at which the delayed sine wave voltage crosses the trigger threshold, and outputs a trigger signal 2 to the trigger light source 14 at the timing when the voltage applied to the electrodes 12A, 12B reaches an arbitrary wave height (e.g., a peak).

[0069] As configured as above, the seventh embodiment also provides the following effect (6) in addition to the effect (1) of the first embodiment.

[0070] (6) The delay circuit 71 is configured to input the waveform signal 6 of the sine wave voltage from the sine wave power supply 21 and give a predetermined time delay to this sine wave voltage, and the trigger circuit 72 is configured to output the trigger signal 2 to the trigger light source 14 at the timing when the delayed sine wave voltage becomes an arbitrary rising voltage or falling voltage. Therefore, the optical switch 70 can be switched to close at any timing before or after the time when the voltage applied to the electrodes 12A and 12B reaches its peak, and the switch signal 3 can be generated from the optical switch 70. As a result, the value of the voltage (the voltage applied to the electrodes 12A and 12B) when the optical switch 70 is switched to close can be adjusted to a desired voltage value, and the switch signal 3 output when the optical switch 70 is closed can be adjusted to a desired voltage value.

[0071] Although the power supply has been described as the sine wave power supply 21, it may be the sine wave power supply 32 (FIG. 5) of the third embodiment that outputs a sine wave voltage having a bias voltage or a modified sine wave voltage. The power supply may be the pulse power supply 13 that applies a pulse voltage at a constant cycle, or the pulse power supply 31 (FIG. 2) of the third embodiment that generates a bias voltage and applies a pulse voltage at a constant cycle.

[0072] Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, changes, and combinations can be made without departing from the spirit of the invention. Furthermore, these substitutions, changes, and combinations are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0073] 1... trigger light, 2... trigger signal, 3... switch signal, 5... gate signal, 6... waveform signal, 10... optical switch, 11... semiconductor substrate, 12A, 12B... electrodes, 13... pulsed power supply, 14... trigger light source, 15... trigger signal output means, 15M... voltage measuring means, 15N... voltage peak detection means, 16... trigger light introduction surface, 17... carrier generation region, 20... optical switch, 21... sine wave power supply, 30... optical switch, 31... pulsed power supply, 32... sine wave power supply, 40... optical switch, 41... voltage peak detection means, 42... trigger signal output means, 50... optical switch, 51... differentiating circuit, 52... trigger signal output means, 60... optical switch, 61... trigger circuit, 62... trigger signal output means, 70... optical switch, 71... delay circuit, 72... trigger circuit, 73... trigger signal output means

Claims

1. a semiconductor substrate, a pair of electrodes disposed on the semiconductor substrate, a power source connected to the electrodes and applying a voltage between the electrodes, and a trigger light source generating trigger light; The semiconductor substrate is made of a semi-insulating semiconductor, and has a trigger light introduction surface on one side thereof for introducing the trigger light into the inside, and a carrier generation region is provided inside the pair of electrodes in which carriers are generated by the passage of the trigger light, thereby decreasing an electrical resistance value, An optical switch further comprising a trigger signal output means for outputting a trigger signal for generating the trigger light to the trigger light source when the voltage applied to the electrode reaches or nears its peak.

2. 2. The optical switch according to claim 1, wherein the trigger signal output means is configured to include: a voltage measuring means for measuring an applied voltage applied to an electrode from a power supply; and a voltage peak detection means for detecting a peak of the applied voltage measured by the voltage measuring means and outputting a trigger signal to a trigger light source at the timing of this peak.

3. 2. The optical switch according to claim 1, wherein the power supply is a pulse power supply that generates a positive or negative pulse voltage.

4. 4. The optical switch according to claim 3, wherein a rise time of the pulse voltage generated by said pulse power supply is set to 1 ms or less.

5. 2. The optical switch according to claim 1, wherein the power supply is a sine wave power supply that generates a sine wave voltage or a modified sine wave power supply that generates a modified sine wave voltage.

6. 6. The optical switch according to claim 5, wherein the frequency of the sine wave voltage generated by the sine wave power supply or the modified sine wave voltage generated by the modified sine wave power supply is set to 250 Hz or higher.

7. 4. The optical switch according to claim 3, wherein the pulsed power supply is configured to output a constant bias voltage lower than the pulsed voltage when the pulsed voltage is not being generated.

8. 6. The optical switch of claim 5, wherein the sine wave power supply is configured to output a sine wave power supply having a positive or negative bias voltage, and the modified sine wave power supply is configured to output a modified sine wave voltage having a positive or negative bias voltage.

9. 2. The optical switch according to claim 1, wherein the trigger signal output means is configured to include: a voltage measuring means for measuring an applied voltage applied to an electrode from a power supply; and a voltage peak detection means for detecting a peak of the applied voltage measured by the voltage measuring means and outputting a trigger signal to a trigger light source at a timing when a predetermined delay time has elapsed since the detection of the peak.

10. the trigger signal output means includes a voltage measuring means for measuring an applied voltage applied to an electrode from a pulse power supply, and a differentiation circuit for differentiating the applied voltage measured by the voltage measuring means to generate a differentiated signal; the pulse power supply outputs a gate signal having an arbitrary time width to the differential circuit after a predetermined time has elapsed since the start of application of the pulse voltage; 4. The optical switch according to claim 3, wherein the differentiation circuit is configured to output a trigger signal to a trigger light source at the timing when the differentiation signal first reaches a given voltage while receiving the gate signal.

11. 6. The optical switch according to claim 5, wherein the trigger signal output means is configured to have a trigger circuit which inputs a waveform signal of a sine wave voltage from a sine wave power supply or a waveform signal of a modified sine wave voltage from a modified sine wave power supply, and outputs a trigger signal to a trigger light source at the timing when the sine wave voltage or the modified sine wave voltage becomes an arbitrary rising voltage or falling voltage.

12. 6. The optical switch according to claim 5, wherein the trigger signal output means is configured to include a delay circuit which inputs a waveform signal of a sine wave voltage from a sine wave power supply or a waveform signal of a modified sine wave voltage from a modified sine wave power supply and gives a predetermined time delay to the sine wave voltage or the modified sine wave voltage, and a trigger circuit which inputs a delayed sine wave voltage or a delayed modified sine wave voltage from the delay circuit and outputs a trigger signal to a trigger light source at the timing when the delayed sine wave voltage or the delayed modified sine wave voltage becomes an arbitrary rising voltage or falling voltage.

13. a semiconductor substrate, a pair of electrodes disposed on the semiconductor substrate, a power source connected to the electrodes and applying a voltage between the electrodes, and a trigger light source generating trigger light; The semiconductor substrate is made of a semi-insulating semiconductor, and has a trigger light introduction surface on one side thereof for introducing the trigger light into the inside, and a carrier generation region is provided inside the semiconductor substrate corresponding to the pair of electrodes in which carriers are generated by the passage of the trigger light, thereby reducing an electrical resistance value, A method for operating an optical switch, characterized in that a trigger signal output means outputs a trigger signal for generating the trigger light to the trigger light source when the voltage applied to the electrode reaches or nears its peak.

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