A laser-driven semiconductor switch and terahertz pulse chopping system

Abstract

The application belongs to the field of terahertz, and specifically discloses a laser-driven semiconductor switch and a terahertz pulse chopping system. When there is no laser irradiation, a differential displacement platform is used to adjust the distance between a first semiconductor silicon wafer and a second semiconductor silicon wafer, so that the reflected wave power is 0, and the transmitted wave power and the incident wave power are equal. When the first semiconductor silicon wafer is irradiated by the laser, the surface carrier concentration of the first semiconductor silicon wafer and the second semiconductor silicon wafer rises within nanoseconds, the incident wave is totally reflected, and the transmitted wave power is reduced to 0. The application can be used for terahertz waves with different frequencies, propagation directions and polarization directions, and can realize high isolation and low insertion loss of opening and closing.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of terahertz, more specifically, it relates to a laser-driven semiconductor switch and a terahertz pulse chopping system. BACKGROUND

[0002] Electron spin resonance (ESR) is a unique method for detecting unpaired electrons in paramagnetic substances based on the interaction between unpaired electrons and electromagnetic waves of a certain frequency under the action of a magnetic field. An ESR spectrometer is a main analytical instrument for studying the electron spin resonance phenomenon of a substance, which is composed of many systems. The wave source system is used to generate electromagnetic waves required for resonance and is the core of the spectrometer. According to the form of electromagnetic waves generated by the wave source and finally applied to the sample, ESR spectrometers are divided into continuous wave spectrometers and pulsed wave spectrometers. Continuous wave spectrometers are mainly used to detect static information of a substance, while pulsed wave spectrometers use pulsed wave sources with nanosecond-level pulse width to detect dynamic information of a substance and are more widely used. With the development of terahertz wave source technology, the performance of ESR spectrometers has also been significantly developed with the increase of wave source frequency and power, and has entered the terahertz band. For a pulsed wave ESR spectrometer, high frequency can improve the spectral resolution, polarization intensity and sensitivity of the spectrometer; high power can shorten the π / 2 time of the spectrometer and improve the time resolution. When the power reaches the kilowatt level, the π / 2 time can be shortened to within 10 ns, making it possible to detect substances with short relaxation time such as biological macromolecules. The pulsed wave ESR detection of such substances cannot be realized at low power. At present, there are only two types of kilowatt terahertz sources, i.e. gyrotron and free electron laser. The electromagnetic waves generated by them have microsecond or even millisecond pulse width, which cannot be directly applied to pulsed wave ESR and need to be transformed and processed subsequently.

[0003] Chopping technology based on terahertz switch is a common method to transform long pulse width and high power electromagnetic wave into terahertz pulse required by ESR. In the prior art, laser-driven semiconductor switch has the advantage of nanosecond response time, and is a better method to generate nanosecond terahertz pulse. Its principle is that when the laser irradiates the semiconductor window, the carrier concentration on the surface of the semiconductor window rapidly rises, and the semiconductor window changes from originally transmitting terahertz wave to totally reflecting terahertz wave within a few nanoseconds, thereby realizing the switching off of the transmitted wave and the switching on of the reflected wave. However, without laser driving, due to the refraction effect, the semiconductor window will reflect part of the terahertz wave, thereby increasing the insertion loss of the semiconductor switch used for switching off the transmitted wave, and causing a certain bias when switching on the reflected wave, i.e. reducing the isolation, which will seriously affect the performance of the generated terahertz pulse. Therefore, currently, scholars have proposed two methods to realize zero reflection of terahertz wave by semiconductor switch without laser driving. One is to make the propagation direction of terahertz and the normal direction of the semiconductor window into the Brewster angle. Since the refractive index of commonly used semiconductor silicon is 3.4, the Brewster angle reaches 73.7°, which will cause the terahertz transmission path to be relatively deformed, and the transmission efficiency will be significantly reduced. Moreover, this method can only be used for p-polarized terahertz wave, and the application range is relatively narrow. The second method is based on the interference effect of electromagnetic wave. Through a semiconductor window with a specific thickness, zero reflection of terahertz wave by semiconductor switch without laser driving can be realized at a specific frequency. However, this method has a high requirement on the processing precision of the thickness of the semiconductor wafer, reaching microns, and can only be used for a single frequency, which seriously limits the application range of the ESR spectrometer. SUMMARY

[0004] In view of the defects of the prior art, the purpose of the present application is to provide a laser-driven semiconductor switch and a terahertz pulse chopping system based thereon, which aims to solve the problem that the laser-driven semiconductor switch will reflect part of the terahertz wave due to the refraction effect when there is no laser driving, thereby increasing the insertion loss of the semiconductor switch used for switching off the transmitted wave, and causing a certain bias when switching on the reflected wave, i.e. reducing the isolation, which will seriously affect the performance of the generated terahertz pulse.

[0005] To achieve the above-mentioned purpose, in a first aspect, the present application provides a laser-driven semiconductor switch, comprising: a first semiconductor silicon wafer and a second semiconductor silicon wafer arranged in parallel, a first semiconductor silicon wafer support, a second semiconductor silicon wafer support and a micro-displacement platform; the first semiconductor silicon wafer is connected with the micro-displacement platform through the first semiconductor silicon wafer support; the second semiconductor silicon wafer is connected with the micro-displacement platform through the second semiconductor silicon wafer support;

[0006] The differential displacement platform is used for adjusting the distance between the first semiconductor silicon wafer and the second semiconductor silicon wafer to achieve that the reflected wave power is 0, the transmitted wave power is equal to the incident wave power when there is no laser irradiation; when the laser irradiates the first semiconductor silicon wafer, the carrier concentration of the light-receiving surface of the first semiconductor silicon wafer rises in nanoseconds, the incident wave is totally reflected, and the transmitted wave power is reduced to 0; wherein the incident wave is a terahertz wave.

[0007] Further preferably, the first semiconductor silicon wafer and the second semiconductor silicon wafer have the same thickness and are both high-resistance semiconductor silicon wafers.

[0008] Further preferably, the first semiconductor silicon wafer support and the second semiconductor silicon wafer support are made of hard aluminum material and are blackened on the surface.

[0009] Further preferably, the differential displacement platform realizes millimeter-level travel and micron-level resolution for parallel adjustment.

[0010] In a second aspect, the application provides a terahertz pulse chopping system, which comprises a terahertz optical subsystem, a laser subsystem and a laser-driven semiconductor switch.

[0011] The terahertz optical subsystem is used for converting a terahertz wave into a Gaussian light beam, emitting, receiving and transmitting the Gaussian light beam, and detecting the reflected wave power and the transmitted wave power; the laser subsystem is used for providing laser drive for the laser-driven semiconductor switch; the laser-driven semiconductor switch is used for presenting a dielectric state when there is no laser drive, realizing zero reflection and full transmission of the incident wave by adjusting the distance between the first semiconductor silicon wafer and the second semiconductor silicon wafer; and presenting a conductor state under laser drive, and the carrier concentration of the light-receiving surface of the first semiconductor silicon wafer rapidly rises, totally reflects the incident wave, reduces the transmitted wave power to 0, realizes nanosecond-level switching off of the transmitted wave and nanosecond-level switching on of the reflected wave.

[0012] Further preferably, the terahertz optical subsystem comprises a terahertz wave source, a first terahertz detector, a second terahertz detector, a first off-axis parabolic mirror, a second off-axis parabolic mirror, a third off-axis parabolic mirror, a first terahertz transmitting antenna, a second terahertz receiving antenna and a third terahertz receiving antenna.

[0013] The terahertz wave source is used to provide terahertz waves; the first terahertz transmitting antenna is used to transform the terahertz waves into a Gaussian light beam capable of being transmitted at a long distance; the first off-axis parabolic mirror is used to reflect the Gaussian light beam generated by the first terahertz transmitting antenna, so that the Gaussian light beam is transmitted to the laser-driven semiconductor switch; the second off-axis parabolic mirror is used to change the propagation direction of the transmitted wave, so that the transmitted wave is transmitted to the third terahertz receiving antenna; the third off-axis parabolic mirror is used to change the propagation direction of the reflected wave, so that the reflected wave is transmitted to the second terahertz receiving antenna; the first terahertz detector and the second terahertz detector are respectively used to detect the power of the reflected wave and the power of the transmitted wave; the second terahertz receiving antenna and the third terahertz receiving antenna are respectively arranged in front of the first terahertz detector and the second terahertz detector, and are respectively used to receive the reflected wave and the transmitted wave.

[0014] Further preferably, the laser subsystem comprises a laser, a laser plane mirror, a laser beam expander and an arbitrary pulse sequence generator;

[0015] The laser is used to generate laser for driving the laser-driven semiconductor switch; the laser plane mirror and the laser beam expander are used to transmit the laser; and the arbitrary pulse sequence generator is used to time sequence control the laser.

[0016] Further preferably, the terahertz wave source adopts a solid-state wave source, and is used to generate terahertz waves with a frequency of 230GHz-260GHz and a power of hundreds of milliwatts.

[0017] Further preferably, the first terahertz detector and the second terahertz detector adopt zero-bias detectors, and have a frequency range of 170GHz-260GHz.

[0018] Further preferably, the laser adopts a nanosecond laser; and the pulse width of the arbitrary sequence generator is nanoseconds.

[0019] Overall, compared with the prior art, the above technical scheme conceived by the present application has the following beneficial effects:

[0020] The present application provides a laser-driven semiconductor. When there is no laser driving, due to the use of a double-layer semiconductor wafer structure with adjustable spacing, the layer spacing is adjusted to achieve a reflected wave power of 0 and a transmitted wave power equal to an incident wave. When the first semiconductor silicon wafer is irradiated by laser, the carrier concentration of the light-receiving surface of the first semiconductor silicon wafer rises within nanoseconds, the incident wave is completely reflected, and the transmitted wave power is reduced to 0. The laser-driven semiconductor can be used for terahertz waves with different frequencies, propagation directions and polarization directions, to realize high isolation and low insertion loss of opening and closing. At the same time, the error caused by the insufficient processing precision of the flatness and thickness of the silicon wafer can be compensated, and the processing difficulty is greatly reduced. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1is the overall structure diagram of an optical path system for realizing terahertz wave nanosecond-level turn-on and turn-off provided by an embodiment of the present application;

[0022] Figure 2(a) is a three-dimensional structure diagram of a laser-driven semiconductor switch with a double-layer structure provided by an embodiment of the present application;

[0023] Figure 2(b) is an XOZ plane cross-sectional view of a laser-driven semiconductor switch with a double-layer structure provided by an embodiment of the present application;

[0024] Figure 3 is a simulation result diagram of the reflectivity of a semiconductor switch for terahertz waves of different frequencies with respect to the change of layer spacing when there is no laser driving provided by an embodiment of the present application;

[0025] Figure 4(a) is a normalized simulation result diagram of the time-domain variation law of the transmitted wave power of a semiconductor switch with different layer spacings when driven by a laser for a 240 GHz terahertz wave provided by an embodiment of the present application;

[0026] Figure 4(b) is a normalized simulation result diagram of the time-domain variation law of the reflected wave power of a semiconductor switch with different layer spacings when driven by a laser for a 240 GHz terahertz wave provided by an embodiment of the present application;

[0027] Figure 5 is a first bracket design drawing for mounting a silicon wafer with a thickness of 0.4 mm and a diameter of 76.2 mm provided by an embodiment of the present application;

[0028] Figure 6 is a second bracket design drawing for mounting a silicon wafer with a thickness of 0.4 mm and a diameter of 76.2 mm provided by an embodiment of the present application.

[0029] In all the drawings, the same reference signs are used to represent the same elements or structures, wherein:

[0030] S is a laser-driven semiconductor switch; PM1 is a first terahertz off-axis parabolic reflector; PM2 is a second terahertz off-axis parabolic reflector; PM3 is a third terahertz off-axis parabolic reflector; W1 is a terahertz transmitting antenna; W2 is a terahertz receiving antenna for a reflected wave detector; W3 is a terahertz receiving antenna for a transmitted wave; FM is a laser plane reflector; E is a laser beam expander; 1 is a first semiconductor silicon wafer bracket; 2 is a first semiconductor silicon wafer; 3 is a second semiconductor silicon wafer bracket; 4 is a second semiconductor silicon wafer; and 5 is a differential displacement platform. DETAILED DESCRIPTION

[0031] In order to make the purposes, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not used to limit the present application.

[0032] The term "and / or" used herein is used to describe an association relationship of associated objects, which means that there can be three relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. The symbol " / " used herein means that the associated objects are or, for example, A / B means A or B.

[0033] The terms "first" and "second" and the like in the description and claims herein are used to distinguish different objects, and are not used to describe a specific order of the objects.

[0034] In the embodiments of the present application, the words "exemplary" or "for example" are used to mean serving as an example, instance, or illustration. Any embodiment or design presented as "exemplary" or "for example" in the embodiments of the present application should not be construed as being more preferred or advantageous than other embodiments or design solutions. Rather, the use of "exemplary" or "for example" is intended to present concepts in a concrete manner.

[0035] In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise specified.

[0036] In the present application, the laser-driven semiconductor switch is embedded in the transmission light path of the terahertz pulse chopping system. The terahertz pulse chopping system includes a set of terahertz wave sources, two sets of terahertz detectors, three off-axis parabolic mirrors, a terahertz transmitting antenna, two terahertz receiving antennas, a laser, an arbitrary pulse sequence generator, a laser beam expander, and a double-layer laser-driven semiconductor switch. The terahertz wave is generated by the terahertz wave source and is transformed into a Gaussian beam that can be transmitted over a long distance by the transmitting antenna as an incident wave. The off-axis parabolic mirror is used to achieve efficient transmission, and the laser-driven semiconductor switch is used to turn off and turn on the transmitted wave and the reflected wave into the receiving antenna, which is then detected by the detector. The semiconductor switch is turned off and turned on by laser irradiation.

[0037] The laser-driven semiconductor switch provided by the application comprises two layers of semiconductor silicon wafers with the same thickness and parallel to each other, and corresponding mounting supports, the silicon wafers and the supports are connected through vacuum grease, the first and second supports are connected and mounted through a micro-displacement platform, so that the distance between the two layers of silicon wafers is adjustable; in the optical path, the normal of the silicon wafers in the laser-driven semiconductor switch and the transmission direction of the incident wave form a certain angle according to the transmission direction requirement of the reflected wave and the incident wave; when there is no laser irradiation, the semiconductor is in a dielectric state, the reflected wave power is 0 by adjusting the distance between the two layers of silicon wafers, the transmitted wave power is equal to the incident wave, so as to realize low insertion loss for the transmitted wave and high isolation for the reflected wave; when strong laser emitted by a laser irradiates the first semiconductor switch, the surface carrier concentration of the semiconductor wafer rapidly rises within nanosecond time, the semiconductor wafer presents a conductor state, the terahertz wave is totally reflected, the transmitted wave power is reduced to 0, and the switch is turned off, and the reflected wave power is increased to the incident wave power to realize turn-on.

[0038] The embodiments of the application are described below with reference to the drawings in the embodiments of the application.

[0039] The application provides a nanosecond laser-driven semiconductor switch applicable to high-power terahertz waves with different frequencies, transmission directions and polarization directions, which comprises two layers of semiconductor silicon wafers (referred to as a first silicon wafer and a second silicon wafer), two corresponding silicon wafer supports and a micro-displacement platform; a matched terahertz optical path subsystem comprises a wave source for generating a terahertz wave, a first terahertz transmitting antenna W1 for transforming the terahertz wave into a Gaussian beam which can be transmitted at a long distance, a first off-axis parabolic mirror PM1 for realizing efficient transmission of the Gaussian beam, a second off-axis parabolic mirror PM2, a third off-axis parabolic mirror PM3, a first detector and a second detector for detecting the power of a terahertz reflected wave and a transmitted wave respectively, and a second terahertz receiving antenna W2 and a third terahertz receiving antenna W3 for receiving a terahertz Gaussian beam; a matched laser subsystem comprises a laser for generating strong laser for driving the semiconductor switch, a laser plane mirror FM for transmitting the laser, a laser beam expander E and an arbitrary pulse sequence generator for time sequence control of the laser;

[0040] The core of the application is a laser-driven semiconductor switch with a double-layer structure, and the specific structure is shown in FIG. 2 (a) and FIG. 2 (b). In order to describe the positional relationship between the components, it is stipulated that is a horizontal plane, is a vertical direction; the thicknesses of the two layers of semiconductor silicon wafers (a first semiconductor silicon wafer 2 and a second semiconductor silicon wafer 4) are equal, the surfaces thereof are parallel to each other, and the surfaces are parallel to The two silicon wafers are mounted on a planar surface, connected to a first semiconductor silicon wafer support 1 and a second semiconductor silicon wafer support 3 via vacuum grease. Both supports are mounted on the same differential displacement platform 5, thereby achieving distance control between the two silicon wafer layers. The design and installation of the wafer supports and the differential displacement platform must ensure that the two silicon wafer layers remain parallel throughout the interlayer spacing adjustment process. The plane is flat, and the minimum spacing can be adjusted to 0;

[0041] The laser-driven semiconductor switch is embedded in the transmission optical path of the terahertz beam, requiring a matching terahertz optical path system and laser system for its use; the overall system of this application is as follows: Figure 1 As shown, the transmission paths of terahertz waves and lasers are as follows; for ease of explanation, Figure 1 middle The plane is a horizontal plane. Vertical direction; both terahertz waves and lasers are in In-plane transmission;

[0042] Regarding the transmission path of terahertz waves, the terahertz waves transmitted within the system can be divided into incident waves, transmitted waves, and reflected waves. The incident wave, emitted from the terahertz source, is transformed into a Gaussian beam by the first transmitting antenna W1 and propagates parallel to the axis of the first terahertz transmitting antenna W1, i.e., parallel to the Y1 axis. Furthermore, the incident wave beam radius is emitted with the transmission, passing through the first off-axis parabolic reflector PM1 and emitted perpendicularly, thus propagating parallel to the X1 axis and completing beam focusing. The waist of the Gaussian beam is located at the center of the first silicon wafer of the laser-driven semiconductor switch S. The terahertz Gaussian beam passes through the surface of the first silicon wafer, undergoing multiple refractions and reflections between the first and second silicon wafers, resulting in interference. A portion of the Gaussian beam passes through both silicon wafers and exits from the second silicon wafer as a transmitted wave. Another portion is reflected from the surface of the first silicon wafer as a reflected wave. The transmitted wave propagates parallel to the X1 axis, is reflected and focused by the second off-axis parabolic mirror PM2, and its propagation direction becomes parallel to the Y1 axis. The beam waist is located on the surface of the third terahertz receiving antenna W3, and the axis of the third terahertz receiving antenna W3 is also parallel to the Y1 axis. Finally, it is transformed into a waveguide-mode terahertz wave and enters the second detector to realize the power detection of the transmitted wave. The reflected wave is also vertically reflected and focused by the third off-axis parabolic mirror PM3, enters the second terahertz receiving antenna W2, and finally enters the first detector to realize the power detection. The propagation direction of the reflected wave can be arbitrary and adjusted according to the actual situation. It also determines the installation angle of the laser-driven semiconductor switch. When the propagation direction of the reflected wave is at an angle to the incident wave... θ At time 1, according to the law of reflection, the Y2 axis of the laser-driven semiconductor switch forms an angle with the direction of propagation of the incident wave. ;

[0043] As to the generation and transmission of the laser for driving the semiconductor switch, the arbitrary pulse sequence generator controls the laser to generate a small strong laser spot, which is transmitted in parallel to the X1 axis, is reflected to the center of the beam expander E by the laser plane mirror FM, is amplified in synchronization without changing the transmission direction of the laser, and makes a larger spot cover the surface of the semiconductor silicon wafer, so as to drive the semiconductor silicon wafer.

[0044] Further, the working process and principle of the laser-driven semiconductor switch and the terahertz and laser system provided by the application are as follows: when the terahertz wave source continuously outputs power and is not driven by the laser, the silicon wafer is in a dielectric state, the layer spacing between the front and rear two silicon wafers is adjusted by the differential displacement platform, and the reflected wave power and the transmitted wave power detected by the first detector and the second detector are observed; when the detection signal of the second detector is 0 and the signal of the first detector is maximum (the incident wave power), the layer spacing adjustment is completed, the lowest insertion loss of the transmitted wave and the highest isolation of the reflected wave are realized; the arbitrary pulse sequence generator generates an electric pulse signal to drive the laser to generate a high-energy nanosecond laser, which is irradiated on the surface of the first silicon wafer through the laser transmission system, the carrier concentration of the light-receiving surface of the first silicon wafer rapidly rises, becomes a conductor state, and reflects all the terahertz incident waves in the nanosecond time scale, so that the transmitted wave power decreases to 0 and the reflected wave power rises to the maximum value (the incident wave power), thereby realizing the nanosecond shutdown of the transmitted wave and the nanosecond opening of the reflected wave; since the relaxation time of the semiconductor carrier is usually long, the silicon wafer will continuously be in a conductor state, that is, it can maintain the open or closed state for a long time, usually for tens of microseconds.

[0045] The parameters and device models selected in the embodiment are used to construct a nanosecond high-power terahertz semiconductor switch for the full frequency band of 230GHz-260GHz.

[0046] In the laser-driven semiconductor switch, a double-layer high-resistance semiconductor silicon wafer with a thickness of 0.4mm and a diameter of 76.2mm is used, the first support and the second support are made of hard aluminum material and are blackened on the surface, the processing is as shown in Figure 5 and Figure 6 The process is simple, the differential displacement platform can realize high parallel adjustment with a stroke of 13mm and a resolution of 10μm; according to these parameters, through the calculation of the laser-driven semiconductor numerical simulation model, when the semiconductor switch is not driven by the laser, the change rule of the reflectivity of the semiconductor switch with the layer spacing is as shown in Figure 3As shown, the results show that, for terahertz waves of 230GHz~260GHz, the reflectivity can be adjusted to 0 by the layer spacing; when driven by laser with pulse width of 10ns and single pulse energy of 50mJ, the time-domain normalized simulation results of reflected wave and transmitted wave of semiconductor switches with different layer spacings for terahertz waves of 240GHz are shown in Fig. 4(a) and Fig. 4(b), and the results show that the layer spacing only affects the transmitted wave and reflected wave power without laser driving, and does not affect the nanosecond-level turn-off of the transmitted wave and the nanosecond-level turn-on of the reflected wave;

[0047] In terms of supporting system equipment, the terahertz wave source uses a solid-state wave source that can generate terahertz waves with a frequency of 230GHz~260GHz and a power of hundreds of milliwatts; the second and third detectors both use zero-bias detectors with a frequency range of 170GHz~260GHz; the laser uses a nanosecond laser that can output strong laser with a pulse width of 6ns, a single pulse energy of more than 220mJ, and a wavelength of 532nm, which is sufficient to drive any semiconductor switch; the time resolution of the arbitrary sequence generator is 50ps, and the pulse width is 7.5ns~2.6s, which meets the driving requirements of the laser;

[0048] For terahertz quasi-optical elements, the off-axis parabolic mirror is made of hard aluminum with a gold coating, with a clear aperture of 125mm and an effective focal length of 250mm; the transmitting antenna and the receiving antenna use a corrugated horn structure made of brass with a gold coating, with an output aperture of 18mm and a generated Gaussian beam waist radius of 7mm; the laser beam expander can amplify the 532nm laser spot by 2 to 10 times, and the laser reflector can achieve a reflectivity of up to 99% for 532nm laser.

[0049] In summary, compared with the prior art, the present application has the following advantages:

[0050] The present application uses a double-layer semiconductor wafer structure with adjustable spacing, which can achieve high isolation and low insertion loss for opening and closing of terahertz waves with different frequencies, propagation directions and polarization directions by adjusting the layer spacing, and can also compensate for errors caused by insufficient processing accuracy of silicon wafer flatness and thickness, greatly reducing the processing difficulty.

[0051] Compared with the existing technology of achieving zero reflection by making the terahertz wave transmission direction and the semiconductor wafer normal form Brewster angle, the present application achieves zero reflection based on the interference principle of terahertz waves, which is not limited by the propagation direction and the polarization direction, reduces the optical path design difficulty of the terahertz chopping system based thereon, and significantly reduces the transmission loss of the terahertz Gaussian beam in the system.

[0052] Compared with the existing technology of using thickness precision design to realize zero reflection by interference of terahertz waves transmitted and reflected in the semiconductor wafer, the double-layer semiconductor wafer can realize zero reflection at multiple frequencies by adjusting the distance between the two layers, greatly expanding the applicable range.

[0053] It should be understood that expressions such as "include" and "may include" used in the present application indicate the presence of disclosed functions, operations or constituent elements, and do not limit one or more additional functions, operations and constituent elements. In the present application, terms such as "include" and / or "have" can be interpreted to mean that specific features, numbers, operations, constituent elements, components or combinations thereof are present, but cannot be interpreted to exclude the presence or addition of one or more other features, numbers, operations, constituent elements, components or combinations thereof.

[0054] In addition, in the present application, the expression "and / or" includes any and all combinations of the associated listed terms. For example, the expression "A and / or B" can include A, can include B, or can include both A and B.

[0055] In the description of the embodiments of the present application, it should be noted that, unless otherwise explicitly specified and limited, the term "connection" should be understood broadly, for example, "connection" can be detachable connection, or can be non-detachable connection; can be direct connection, or can be indirect connection through intermediate medium. Among them, "fixed connection" means that the relative positional relationship after connection is unchanged. "Rotary connection" means that the relative rotation after connection is connected. "Sliding connection" means that the relative sliding after connection is connected. The orientation language mentioned in the embodiments of the present application, such as "top", "bottom", "inner", "outer", "left", "right", etc., is only the direction of the drawing, therefore, the orientation language used is to better, more clearly illustrate and understand the embodiments of the present application, and is not indicative or implied that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, therefore, it cannot be understood as a limitation on the embodiments of the present application.

[0056] In addition, in the embodiments of the present application, the mathematical concepts mentioned, symmetry, equality, parallel, perpendicular, etc. These limitations are all for the current process level, and are not strictly defined in the mathematical sense, allowing a small amount of deviation, approximately symmetrical, approximately equal, approximately parallel, approximately perpendicular, etc. For example, A is parallel to B, which means that A and B are parallel or approximately parallel, the included angle between A and B can be between 0 degrees and 10 degrees. A and B are perpendicular, which means that A and B are perpendicular or approximately perpendicular, the included angle between A and B can be between 80 degrees and 100 degrees.

[0057] The above merely provides the specific implementation of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A laser-driven semiconductor switch, characterized in that, include: A first semiconductor silicon wafer and a second semiconductor silicon wafer, a first semiconductor silicon wafer support, a second semiconductor silicon wafer support, and a differential displacement platform arranged in parallel; The first semiconductor silicon wafer is connected to the differential displacement platform via a first semiconductor silicon wafer support; the second semiconductor silicon wafer is connected to the differential displacement platform via a second semiconductor silicon wafer support. When there is no laser irradiation, the differential displacement platform is used to adjust the distance between the first and second semiconductor silicon wafers to achieve zero reflected wave power and equal transmitted wave power and incident wave power. When the laser irradiates the first semiconductor silicon wafer, the carrier concentration on the light-receiving surface of the first semiconductor silicon wafer increases within a nanosecond time, the incident wave is completely reflected, and the transmitted wave power drops to zero. The incident wave is a terahertz wave.

2. The laser-driven semiconductor switch according to claim 1, characterized in that, The first and second semiconductor silicon wafers have the same thickness and are both high-resistivity semiconductor silicon wafers.

3. The laser-driven semiconductor switch according to claim 1 or 2, characterized in that, The first and second semiconductor silicon wafer supports are made of hard aluminum with a blackened surface treatment.

4. The laser-driven semiconductor switch according to claim 1, characterized in that, The differential displacement platform achieves millimeter-level stroke and micrometer-level parallel adjustment with resolution.

5. A terahertz pulse chopper system, characterized in that, include: Terahertz optical circuit subsystem, laser subsystem, and laser-driven semiconductor switch based on any one of claims 1 to 4; The terahertz optical circuit subsystem is used to convert terahertz waves into Gaussian beams and to transmit, receive, and transmit the Gaussian beams, as well as to detect the power of reflected and transmitted waves. The laser subsystem is used to provide laser drive for the laser-driven semiconductor switch. The laser-driven semiconductor switch is used to present a dielectric state when there is no laser drive, and to achieve zero reflection and full transmission of incident waves by adjusting the spacing between the first and second semiconductor silicon wafers. Under laser drive, it presents a conductor state, and the carrier concentration on the light-receiving surface of the first semiconductor silicon wafer rises rapidly, reflecting all incident waves and reducing the power of transmitted waves to 0, thus achieving nanosecond-level shutdown of transmitted waves and nanosecond-level switching on of reflected waves.

6. The terahertz pulse chopper system according to claim 5, characterized in that, The terahertz optical circuit subsystem includes a terahertz wave source, a first terahertz detector, a second terahertz detector, a first off-axis parabolic mirror, a second off-axis parabolic mirror, a third off-axis parabolic mirror, a first terahertz transmitting antenna, a second terahertz receiving antenna, and a third terahertz receiving antenna. A terahertz wave source is used to provide terahertz waves; a first terahertz transmitting antenna is used to convert the terahertz waves into a Gaussian beam capable of long-distance transmission; a first off-axis parabolic reflector is used to reflect the Gaussian beam generated by the first terahertz transmitting antenna, allowing it to be transmitted to a laser-driven semiconductor switch; a second off-axis parabolic reflector is used to change the propagation direction of the transmitted wave, allowing it to be transmitted to a third terahertz receiving antenna; a third off-axis parabolic reflector is used to change the propagation direction of the reflected wave, allowing it to be transmitted to a second terahertz receiving antenna; a first terahertz detector and a second terahertz detector are used to detect the power of the reflected wave and the power of the transmitted wave, respectively; a second terahertz receiving antenna and a third terahertz receiving antenna are respectively positioned in front of the first terahertz detector and the second terahertz detector, and are used to receive the reflected wave and the transmitted wave, respectively.

7. The terahertz pulse chopper system according to claim 5 or 6, characterized in that, The laser subsystem includes a laser, a laser plane mirror, a laser beam expander, and an arbitrary pulse sequence generator; Lasers are used to generate laser light that drives laser-driven semiconductor switches; laser plane mirrors and laser beam expanders are used to transmit laser light; arbitrary pulse sequence generators are used to time-control lasers.

8. The terahertz pulse chopper system according to claim 6, characterized in that, The terahertz wave source uses a solid-state wave source to generate terahertz waves with a frequency of 230GHz~260GHz and a power of hundreds of milliwatts.

9. The terahertz pulse chopper system according to claim 6 or 8, characterized in that, The first and second terahertz detectors are zero-bias detectors with a frequency range of 170 GHz to 260 GHz.

10. The terahertz pulse chopper system according to claim 7, characterized in that, The laser is a nanosecond laser; the pulse width of the arbitrary sequence generator is on the nanosecond level.

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