Laser-driven semiconductor switch and terahertz pulse chopping system

Abstract

The invention belongs to the field of terahertz, and particularly discloses a laser-driven semiconductor switch and a terahertz pulse chopping system. Wherein in the absence of laser irradiation, the differential displacement platform is used for adjusting the distance between the first semiconductor silicon wafer and the second semiconductor silicon wafer, so that the reflected wave power is zero, and the transmitted wave power is equal to the incident wave power; when laser irradiates the first semiconductor silicon wafer, the surface carrier concentration of the first semiconductor silicon wafer and the second semiconductor silicon wafer is increased within nanosecond time, incident waves are completely reflected, and the power of transmitted waves is reduced to 0; according to the invention, turning-on and turning-off with high isolation and low insertion loss can be realized for terahertz waves with different frequencies, propagation directions and polarization directions.

Description

Technical Field

[0001] This application belongs to the terahertz field, and more specifically, relates to a laser-driven semiconductor switch and a terahertz pulse chopping system. Background Art

[0002] Electron spin resonance (ESR) is the only means to detect unpaired electrons in paramagnetic substances based on the Zeeman splitting of unpaired electrons under the action of a magnetic field and their interaction with electromagnetic waves of a certain frequency. An ESR spectrometer is the main analytical instrument for studying the electron spin resonance phenomenon of substances. It consists of many systems, among which the wave source system is used to generate the electromagnetic waves required for resonance and is the core of the spectrometer. According to the different forms of electromagnetic waves generated by the wave source and finally applied to the sample, ESR spectrometers are divided into two types: continuous wave spectrometers and pulsed wave spectrometers. Continuous wave spectrometers are mainly used to detect the static information of substances, while pulsed wave spectrometers use a pulsed wave source with a pulse width of nanoseconds to detect the dynamic information of substances and are more widely used. With the development of terahertz wave source technology, the performance of ESR spectrometers has also developed significantly with the increase in wave source frequency and power, and has now entered the terahertz band. For pulsed wave ESR spectrometers, high frequency can improve the performance of the spectrometer such as spectral resolution, polarization intensity, and sensitivity; 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 times such as biological macromolecules. The pulsed wave ESR detection of such substances cannot be achieved at low power. Currently, there are only two types of terahertz sources at the kilowatt level: gyrotrons and free electron lasers. The pulse widths of the electromagnetic waves they generate are in the microsecond or even millisecond level and cannot be directly applied to pulsed wave ESR and need subsequent transformation and processing.

[0003] The chopping technique based on terahertz switches is a common method to convert long-pulse high-power electromagnetic waves into terahertz pulses required by ESR. In the prior art, laser-driven semiconductor switches have the advantage of nanosecond-level response time and are a relatively optimal method for generating nanosecond-level terahertz pulses. Its principle is that when a laser irradiates a semiconductor window, the carrier concentration on its surface rapidly rises, and the semiconductor window changes from originally transmitting terahertz waves to fully reflecting terahertz waves within a few nanoseconds, achieving the turn-off of the transmitted wave and the turn-on of the reflected wave. However, when there is no laser drive, due to the refraction effect, the semiconductor window will reflect a part of the terahertz waves, which will increase the insertion loss of the semiconductor switch used to turn off the transmitted wave and cause a certain bias when turning on the reflected wave, that is, the isolation degree decreases, which will seriously affect the performance of the generated terahertz pulses. For this reason, currently, scholars have proposed two methods to achieve zero reflection of terahertz waves by semiconductor switches without laser drive. One is to make the propagation direction of terahertz form a Brewster angle with the normal direction of the semiconductor window. Since the refractive index of the commonly used semiconductor silicon is 3.4, the Brewster angle reaches 73.7°, which will lead to a relatively deformed terahertz transmission optical path and a significant reduction in transmission efficiency, and this method can only be used for terahertz waves in the p-polarization direction, with a narrow application range. The other is based on the interference effect of electromagnetic waves. By a semiconductor window with a specific thickness, zero reflection of terahertz waves by the semiconductor switch without laser drive can be achieved at a specific frequency. However, this method has very high requirements for the processing accuracy of the thickness of the semiconductor wafer, reaching the micron level, and can only be used for a single frequency, severely limiting the application range of the ESR spectrometer. Summary of the Invention

[0004] Aiming at 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 on it, aiming to solve the problem that when the laser-driven semiconductor switch has no laser drive, due to the refraction effect, the semiconductor window will reflect a part of the terahertz waves, which will increase the insertion loss of the semiconductor switch used to turn off the transmitted wave and cause a certain bias when turning on the reflected wave, that is, the isolation degree decreases, which will seriously affect the performance of the generated terahertz pulses.

[0005] To achieve the above purpose, in the first aspect, the present application provides a laser-driven semiconductor switch, including: a first semiconductor silicon wafer and a second semiconductor silicon wafer arranged in parallel, a first semiconductor silicon wafer bracket, a second semiconductor silicon wafer bracket, and a differential displacement platform; the first semiconductor silicon wafer is connected to the differential displacement platform through the first semiconductor silicon wafer bracket; the second semiconductor silicon wafer is connected to the differential displacement platform through the second semiconductor silicon wafer bracket; When there is no laser irradiation, the differential displacement platform is used to adjust the distance between the first semiconductor silicon wafer and the second semiconductor silicon wafer to achieve a reflection wave power of 0 and the transmission wave power equal to the incident wave power; when the first semiconductor silicon wafer is irradiated with laser, the carrier concentration on the light-receiving surface of the first semiconductor silicon wafer rises within nanoseconds, the incident wave is completely reflected, and the transmission wave power drops to 0; wherein, the incident wave is a terahertz wave.

[0006] 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.

[0007] Further preferably, the first semiconductor silicon wafer bracket and the second semiconductor silicon wafer bracket are made of duralumin and are surface blackened.

[0008] Further preferably, the differential displacement platform achieves a millimeter-level stroke and a micron-level resolution for parallel adjustment.

[0009] In a second aspect, the present application provides a terahertz pulse chopping system, including a terahertz optical path subsystem, a laser subsystem, and a laser-driven semiconductor switch; The terahertz optical path subsystem is used to convert the terahertz wave into a Gaussian beam, and is used to emit, receive, and transmit the Gaussian beam, and detect the reflection wave power and the transmission wave power; 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 by adjusting the distance between the first semiconductor silicon wafer and the second semiconductor silicon wafer, achieve zero reflection and full transmission of the incident wave; when driven by laser, it presents a conductor state, and the carrier concentration on the light-receiving surface of the first semiconductor silicon wafer rises rapidly, completely reflecting the incident wave and reducing the transmission wave power to 0, realizing nanosecond-level turn-off of the transmission wave and nanosecond-level turn-on of the reflection wave.

[0010] Further preferably, the terahertz optical path subsystem includes a terahertz wave source, a first terahertz detector, a second terahertz detector, a first off-axis parabolic reflector, a second off-axis parabolic reflector, a third off-axis parabolic reflector, a first terahertz transmitting antenna, a second terahertz receiving antenna, and a third terahertz receiving antenna; The terahertz wave source is used to provide terahertz waves; the first terahertz transmitting antenna is used to transform the terahertz waves into Gaussian beams capable of long-distance transmission; the first off-axis parabolic reflector is used to reflect the Gaussian beams generated by the first terahertz transmitting antenna so that they are transmitted to the laser-driven semiconductor switch; the second off-axis parabolic reflector 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 reflector 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 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.

[0011] Further preferably, the laser subsystem includes a laser, a laser plane mirror, a laser beam expander, and an arbitrary pulse sequence generator; The laser is used to generate the laser for driving the laser-driven semiconductor switch; the laser plane mirror and the laser beam expander are used to transmit the laser; the arbitrary pulse sequence generator is used for timing control of the laser.

[0012] Further preferably, the terahertz wave source adopts a solid-state wave source, which is used to generate terahertz waves with a frequency of 230 GHz to 260 GHz and a power of hundreds of milliwatts.

[0013] Further preferably, the first terahertz detector and the second terahertz detector adopt zero-bias detectors with a frequency range of 170 GHz to 260 GHz.

[0014] Further preferably, the laser adopts a nanosecond laser; the pulse width of the arbitrary sequence generator is of nanosecond level.

[0015] Generally speaking, compared with the prior art, the above technical solution conceived by this application has the following beneficial effects: This application provides a laser-driven semiconductor. When there is no laser drive, due to the use of a double-layer semiconductor wafer structure with adjustable spacing, by adjusting the layer spacing, the power of the reflected wave can be made 0, and the power of the transmitted wave is equal to that of the incident wave. When the first semiconductor silicon wafer is irradiated by the laser, the carrier concentration on the light-receiving surface of the first semiconductor silicon wafer rises within nanoseconds, and the incident wave is all reflected, and the power of the transmitted wave drops to 0. It can achieve the opening and closing with high isolation and low insertion loss for terahertz waves with different frequencies, propagation directions, and polarization directions. At the same time, it can make up for the errors caused by the insufficient processing accuracy of the flatness and thickness of the silicon wafer, greatly reducing the processing difficulty. Description of the Drawings

[0016] Figure 1It is the overall structure diagram of the optical path system provided by the embodiments of the present application for realizing the nanosecond-level turn-on and turn-off of terahertz waves; Figure 2(a) is the three-dimensional structure diagram of the laser-driven semiconductor switch with a double-layer structure provided by the embodiments of the present application; Figure 2(b) is the sectional view of the XOZ plane of the laser-driven semiconductor switch with a double-layer structure provided by the embodiments of the present application; Figure 3 It is the simulation result diagram of the variation law of the reflectivity of the semiconductor switch for terahertz waves with different frequencies with respect to the layer spacing when there is no laser drive provided by the embodiments of the present application; Figure 4(a) is the normalized simulation effect diagram of the time-domain variation law of the transmitted wave power when the semiconductor switch with different layer spacings is driven by a laser for terahertz waves of 240 GHz provided by the embodiments of the present application; Figure 4(b) is the normalized simulation result diagram of the time-domain variation law of the reflected wave power when the semiconductor switch with different layer spacings is driven by a laser for terahertz waves of 240 GHz provided by the embodiments of the present application; Figure 5 It is the design drawing of the first bracket for installing a silicon wafer with a thickness of 0.4 mm and a diameter of 76.2 mm provided by the embodiments of the present application; Figure 6 It is the design drawing of the second bracket for installing a silicon wafer with a thickness of 0.4 mm and a diameter of 76.2 mm provided by the embodiments of the present application.

[0017] In all the drawings, the same reference numerals are used to represent the same elements or structures, where: S is the laser-driven semiconductor switch; PM1 is the first terahertz off-axis parabolic mirror; PM2 is the second terahertz off-axis parabolic mirror; PM3 is the third terahertz off-axis parabolic mirror; W1 is the terahertz transmitting antenna; W2 is the terahertz receiving antenna for the reflected wave detector; W3 is the terahertz receiving antenna for the transmitted wave; FM is the laser plane mirror; E is the laser beam expander; 1 is the first semiconductor silicon wafer bracket; 2 is the first semiconductor silicon wafer; 3 is the second semiconductor silicon wafer bracket; 4 is the second semiconductor silicon wafer; 5 is the differential displacement platform. Detailed implementation manners

[0018] In order to make the purpose, 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 are not used to limit the present application.

[0019] As used herein, the term "and / or" describes the relationship between associated objects and represents three possible relationships. For example, A and / or B can represent: A exists alone, both A and B exist simultaneously, and B exists alone. The symbol " / " in this document indicates that the associated objects are in an "or" relationship. For example, A / B means A or B.

[0020] In the description of the specification and claims of this application, terms such as "first" and "second" are used to distinguish different objects, rather than to describe a specific order of the objects.

[0021] In the embodiments of this application, words such as "exemplary" or "for example" are used to give examples, illustrations, or explanations. Any embodiment or design solution described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Rather, the use of words such as "exemplary" or "for example" is intended to present relevant concepts in a specific manner.

[0022] In the description of the embodiments of this application, unless otherwise specified, the meaning of "a plurality" refers to two or more.

[0023] In this application, the laser-driven semiconductor switch is embedded in the transmission optical 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 reflectors, a terahertz transmitting antenna, two terahertz receiving antennas, a laser, an arbitrary pulse sequence generator, a laser beam expander, and a laser-driven semiconductor switch with a double-layer structure; 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 the incident wave, it is efficiently transmitted through the off-axis parabolic reflector and passes through the laser-driven semiconductor switch, and then enters the receiving antenna as the transmitted wave and the reflected wave respectively, and is thus detected by the detector. The semiconductor switch realizes the turn-off and turn-on of the transmitted wave and the reflected wave through laser irradiation.

[0024] The laser-driven semiconductor switch provided by the present application includes a first and a second layer of semiconductor silicon wafers with the same thickness and parallel to each other, as well as corresponding mounting brackets. The wafers and the brackets are connected by vacuum grease. The first and second brackets are connected and mounted through a differential displacement platform, so that the distance between the two layers of wafers is adjustable; in the optical path, according to the transmission direction requirements of the reflected wave and the incident wave, the normal direction of the wafer in the laser-driven semiconductor switch forms a certain angle with the transmission direction of the incident wave; when there is no laser irradiation, the semiconductor is in a dielectric state, and by adjusting the distance between the two layers of wafers, the reflected wave power is made 0, and the transmitted wave power is equal to the incident wave power, thereby achieving low insertion loss for the transmitted wave and high isolation for the reflected wave; when the first semiconductor switch is irradiated by a strong laser emitted by a laser, the surface carrier concentration thereof rapidly rises within nanoseconds, the semiconductor wafer presents a conductor state, the terahertz wave is completely reflected, the transmitted wave power drops to 0, achieving turn-off, and the reflected wave power rises to the incident wave power to achieve turn-on.

[0025] The embodiments of the present application will be described below with reference to the accompanying drawings in the embodiments of the present application.

[0026] The present application provides a nanosecond laser-driven semiconductor switch applicable to high-power terahertz waves with different frequencies, transmission directions, and polarization directions, including: two semiconductor silicon wafers (referred to as the first wafer and the second wafer) in the front and back, corresponding two wafer brackets, and a differential displacement platform; the supporting terahertz optical path subsystem includes: a wave source for generating terahertz waves, a first terahertz transmitting antenna W1 for converting the terahertz waves into Gaussian beams that can be transmitted over long distances, a first off-axis parabolic reflector PM1 for realizing the efficient transmission of Gaussian beams, a second off-axis reflector PM2, a third off-axis reflector PM3, a first detector and a second detector for detecting the terahertz reflected wave and transmitted wave power respectively, and corresponding second terahertz receiving antenna W2 and third terahertz receiving antenna W3 for receiving terahertz Gaussian beams; the supporting laser subsystem includes: a laser for generating a strong laser for driving the semiconductor switch, a laser plane reflector FM for transmitting the laser, a laser beam expander E, and an arbitrary pulse sequence generator for timing control of the laser; The core of the present application is a laser-driven semiconductor switch with a double-layer structure. The specific structure is shown in Figures 2(a) and 2(b). For the convenience of describing the positional relationship between components, it is stipulated that is the horizontal plane, is the vertical direction; the two semiconductor silicon wafers in the front and back (the first semiconductor silicon wafer 2 and the second semiconductor silicon wafer 4) have the same thickness, parallel surfaces, and are parallel to Plane; Two-layer silicon wafers are respectively connected and installed to the first semiconductor silicon wafer support 1 and the second semiconductor silicon wafer support 3 through vacuum grease. Both supports are installed on the same differential displacement platform 5, thereby realizing the distance control between the two-layer silicon wafers. Regarding the design and installation of the silicon wafer supports and the differential displacement platform, it is necessary to ensure that during the layer spacing adjustment process, the two-layer silicon wafers always remain parallel to the plane, and the minimum spacing can be adjusted to 0; The laser-driven semiconductor switch is embedded in the transmission optical path of the terahertz beam, and its use requires a supporting terahertz optical path system and laser system; The overall system of this application is as Figure 1 shown, and the transmission paths of the terahertz wave and the laser are as follows; For the convenience of explanation, Figure 1 in the plane is the horizontal plane, is the vertical direction; Both the terahertz wave and the laser are transmitted within the plane; Regarding the transmission path of the terahertz wave, the terahertz wave transmitted within the system can be divided into an incident wave, a transmitted wave, and a reflected wave; Regarding the incident wave, it is emitted from the terahertz wave source, transformed into a Gaussian beam through the first transmitting antenna W1, and transmitted parallel to the axis of the first terahertz transmitting antenna W1, that is, parallel to the Y1 axis; Further, the beam radius of the incident wave beam emits as it transmits, passes through the first off-axis parabolic reflector PM1, and is vertically emitted, thus transmitting parallel to the X1 axis direction and completing beam focusing. The beam 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, undergoes multiple refractions and reflections between the first silicon wafer and the second silicon wafer, and an interference effect occurs; A part of the Gaussian beam passes through the two-layer silicon wafers and exits from the second silicon wafer as a transmitted wave; Another part is reflected from the surface of the first silicon wafer as a reflected wave; The transmitted wave is transmitted parallel to the X1 axis direction, reflected and focused by the second off-axis parabolic reflector PM2, and the transmission 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 terahertz wave in waveguide mode and enters the second detector to realize the detection of the transmitted wave power; The reflected wave also realizes vertical reflection and focusing through the third off-axis parabolic reflector PM3, enters the second terahertz receiving antenna W2, and finally enters the first detector to realize power detection; The transmission direction of the reflected wave can be any direction, adjusted according to the actual situation, and at the same time, it also determines the installation angle of the laser-driven semiconductor switch. When the transmission direction of the reflected wave forms an angle θ 1 with the incident wave, according to the law of reflection, the Y2 axis in the laser-driven semiconductor switch forms an angle with the transmission direction of the incident wave; Regarding the generation and transmission of laser for driving semiconductor switches, an arbitrary pulse sequence generator controls the timing of the laser to generate a strong laser with a small spot, which is transmitted parallel to the X1 axis. The laser spot is reflected to the center of the beam expander E through the laser plane mirror FM, and the beam expander synchronously amplifies the spot without changing the laser transmission direction, and makes the larger spot cover the surface of the semiconductor silicon wafer, thereby driving the semiconductor silicon wafer; Furthermore, the working process and principle of the laser-driven semiconductor switch and the terahertz and laser system provided in this application are as follows: The terahertz wave source continuously outputs power. When there is no laser drive, the silicon wafer presents a dielectric state. The layer spacing between the front and rear silicon wafers is adjusted through a differential displacement platform, and the reflected wave power and 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 the largest (incident wave power), the layer spacing adjustment is completed, achieving the lowest insertion loss for the transmitted wave and the highest isolation for the reflected wave; An arbitrary pulse sequence generator generates an electrical pulse signal to drive the laser to generate high-energy nanosecond laser, which is irradiated on the surface of the first silicon wafer through the laser transmission system. The carrier concentration on the light-receiving surface of the first silicon wafer rapidly increases and becomes a conductor state, reflecting all the terahertz incident waves within the nanosecond time scale, reducing the transmitted wave power to 0, and increasing the reflected wave power to the maximum value (incident wave power), thereby achieving nanosecond-level turn-off for the transmitted wave and nanosecond-level turn-on for the reflected wave; Due to the usually long relaxation time of semiconductor carriers, the silicon wafer will remain in the conductor state, that is, it can maintain the on or off state for a long time, usually dozens of microseconds.

[0027] The parameters and equipment models selected in this embodiment are used to construct a nanosecond-level high-power terahertz semiconductor switch for full-band use from 230 GHz to 260 GHz; In the laser-driven semiconductor switch, a double-layer high-resistance semiconductor silicon wafer with a thickness of 0.4 mm and a diameter of 76.2 mm is used. The first bracket and the second bracket are made of duralumin material and are blackened on the surface. Its processing is as Figure 5 and Figure 6 shown. The process is simple. The differential displacement platform can achieve high-parallelism adjustment with a stroke of 13 mm and a resolution of 10 μm; According to these parameters, through the calculation of the laser-driven semiconductor numerical simulation model, when there is no laser drive, the variation law of the semiconductor switch reflectivity with the layer spacing is as Figure 3As shown in the figure, the results show that for terahertz waves in the range of 230 GHz to 260 GHz, the reflectivity can be adjusted to 0 through the layer spacing; when driven by a laser with a pulse width of 10 ns and a single pulse energy of 50 mJ, for terahertz waves at 240 GHz, the time-domain normalized simulation results of the reflected wave and transmitted wave of semiconductor switches with different layer spacings are shown in Figures 4(a) and 4(b). The results show that the layer spacing only affects the power of the transmitted wave and reflected wave without laser drive, and does not affect the nanosecond-level turn-off of the transmitted wave and the nanosecond-level turn-on of the reflected wave; In terms of the supporting system equipment, the terahertz wave source uses a solid-state wave source, which can generate terahertz waves with a frequency range of 230 GHz to 260 GHz and a power of hundreds of milliwatts; both the second detector and the third detector use zero-bias detectors, and the frequency range of this detector is 170 GHz to 260 GHz; the laser uses a nanosecond laser, which can output a strong laser with a pulse width of 6 ns, a single pulse energy exceeding 220 mJ, and a wavelength of 532 nm, which is sufficient to drive any semiconductor switch; the time resolution of the arbitrary sequence generator is 50 ps, and the pulse width is 7.5 ns to 2.6 s, meeting the driving requirements of the laser; For terahertz quasi-optical elements, the off-axis parabolic reflector is made of hard aluminum gold-plated material, with a clear aperture of 125 mm and an effective focal length of 250 mm; the transmitting antenna and receiving antenna adopt a corrugated horn structure, made of brass gold-plated material, with a corrugated horn output aperture of 18 mm and a Gaussian beam waist radius of 7 mm; the laser beam expander can magnify the 532 nm laser spot by 2 to 10 times, and the laser mirror can achieve a reflectivity of up to 99% for 532 nm laser.

[0028] In summary, compared with the prior art, the present application has the following advantages: Due to the use of a double-layer semiconductor wafer structure with adjustable spacing in the present application, by adjusting the layer spacing, the opening and closing of high isolation and low insertion loss can be achieved for terahertz waves with different frequencies, propagation directions, and polarization directions. At the same time, the errors caused by the insufficient processing accuracy of the flatness and thickness of the silicon wafer can be compensated, greatly reducing the processing difficulty.

[0029] Compared with the existing technology that realizes zero reflection by making the propagation direction of terahertz waves form a Brewster angle with the normal direction of the semiconductor wafer, since the present application realizes zero reflection based on the interference principle of terahertz waves, it is not restricted by the propagation direction and polarization direction, reducing the optical path design difficulty of the terahertz chopper system based on it, and significantly reducing the transmission loss of terahertz Gaussian beams in the system.

[0030] Compared with the existing technology that achieves zero reflection through the interference of terahertz waves transmitted and reflected inside a semiconductor wafer with precise thickness design, the double-layer semiconductor wafer used in this application can achieve zero reflection at multiple frequencies by adjusting the distance between the two layers, greatly expanding the applicable range.

[0031] It should be understood that expressions such as "including" and "may include" that can be used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as "including" and / or "having" can be interpreted as indicating a specific characteristic, number, operation, constituent element, component, or a combination thereof, but cannot be interpreted as excluding the existence or possibility of addition of one or more other characteristics, numbers, operations, constituent elements, components, or a combination thereof.

[0032] In addition, in this application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" can include A, can include B, or can include both A and B.

[0033] In the description of the embodiments of this application, it should be noted that unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. Among them, "fixed connection" means that the two are connected and the relative positional relationship after connection remains unchanged. "Rotational connection" means that the two are connected and can rotate relative to each other after connection. "Sliding connection" means that the two are connected and can slide relative to each other after connection. The orientation terms mentioned in the embodiments of this application, such as "top", "bottom", "inside", "outside", "left", "right", etc., are only references to the directions in the drawings. Therefore, the orientation terms used are for better and clearer description and understanding of the embodiments of this application, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the embodiments of this application.

[0034] In addition, in the embodiments of this application, mathematical concepts such as symmetry, equality, parallelism, and perpendicularity are mentioned. These limitations are all in view of the current technological level, rather than absolute strict definitions in the mathematical sense. A small deviation is allowed, and approximate symmetry, approximate equality, approximate parallelism, approximate perpendicularity, etc. are all acceptable. For example, when A is parallel to B, it means that A is parallel to B or approximately parallel to B, and the included angle between A and B can be between 0 degrees and 10 degrees. When A is perpendicular to B, it means that A is perpendicular to B or approximately perpendicular to B, and the included angle between A and B can be between 80 degrees and 100 degrees.

[0035] As described above, it is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should all be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims described above.

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 are 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 semiconductor silicon wafer and the second semiconductor silicon wafer to achieve that the reflected wave power is 0 and the transmitted wave power is equal to the 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 nanoseconds, the incident wave is completely reflected, and the transmitted wave power drops to 0; wherein the incident wave is a terahertz wave.

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

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

4. The laser driven semiconductor switch according to claim 1, characterized in that: The differential displacement platform achieves millimeter-level travel and micron-level parallel adjustment.

5. A terahertz pulse chopping system, characterized in that: include: A terahertz optical path subsystem, a laser subsystem, and a laser-driven semiconductor switch according to any one of claims 1 to 4; The terahertz optical path subsystem is used to convert terahertz waves into Gaussian light beams, and is used to emit, receive and transmit Gaussian light beams, and detect the reflected wave power and the transmitted wave power; 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 by adjusting the spacing between the first semiconductor silicon wafer and the second semiconductor silicon wafer, the incident wave is fully transmitted with zero reflection; 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, the incident wave is fully reflected, and the transmitted wave power is reduced to 0, thereby achieving nanosecond shutdown of the transmitted wave and nanosecond opening of the reflected wave.

6. The terahertz pulse chopping system according to claim 5, characterized in that: The terahertz optical path subsystem includes a terahertz wave source, a first terahertz detector, a second terahertz detector, a first off-axis parabolic reflector, a second off-axis parabolic reflector, a third off-axis parabolic reflector, a first terahertz transmitting antenna, a second terahertz receiving antenna and a third terahertz receiving antenna; 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 beam that can be transmitted over a long distance; the first off-axis parabolic reflector is used to reflect the Gaussian beam generated by the first terahertz transmitting antenna and transmit it to the laser-driven semiconductor switch; the second off-axis parabolic reflector is used to change the propagation direction of the transmitted wave and transmit the transmitted wave to the third terahertz receiving antenna; the third off-axis parabolic reflector is used to change the propagation direction of the reflected wave and transmit the reflected wave to the second terahertz receiving antenna; the first terahertz detector and the second terahertz detector are used to detect the power of the reflected wave and the power of the transmitted wave respectively; 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 used to receive the reflected wave and the transmitted wave respectively.

7. The terahertz pulse chopping system according to claim 5 or 6, characterized in that: The laser subsystem includes a laser, a laser plane reflector, a laser beam expander and an arbitrary pulse sequence generator; The laser is used to generate laser light for driving the laser driving semiconductor switch; the laser plane reflector and the laser beam expander are used to transmit the laser light; and the arbitrary pulse sequence generator is used to control the laser light in a timing manner.

8. The terahertz pulse chopping 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 chopping system according to claim 6 or 8, characterized in that: The first terahertz detector and the second terahertz detector use zero-bias detectors with a frequency range of 170 GHz to 260 GHz.

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

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