96 results about "Photoconductive antenna" patented technology

The invention discloses a terahertz pulse measurement-based burning temperature sensing device and a terahertz pulse measurement-based burning temperature sensing method. Laser is emitted from a femtosecond laser device, and is divided into reference laser and detection laser through a beam splitter, the detection laser is focused on a photoconduction antenna type terahertz emitter, terahertz pulses emitted by the terahertz emitter are focused on a ZnTe crystal through an off-axis paraboloid lens group; and the reference layer is collimated and is coincident with terahertz waves focused on the ZnTe crystal after passing through a semi-transmission and self-reflection mirror, parallel grating groups and a polarizing film, the terahertz waves are modulated by using Pockels effect of the ZnTe crystal, and image signals corresponding to collected first reference layer carrying terahertz pulse strength information and second reference laser not carrying the terahertz pulse strength information are input into a computer by a CCD (Charge Coupling Device) detector for subsequence processing. According to the invention, the precision and speed of the non-contact combustion measurement method are increased, and the non-contact measurement of combustion object temperature and temperature distribution is realized.

A system for emitting and detecting terahertz frequency electromagnetic pulses. The system comprises a single transceiver device, which may be an electro-optic crystal or photoconductive antenna, for both emitting and detecting the pulses. A related method comprises using a single transceiver device to both emit and detect electromagnetic terahertz frequency pulses. The transceiver device is excited by a pump pulse to emit a terahertz output pulse, which is modulated with a chopper. An object reflects the terahertz pulse and the reflected pulse is detected in the transceiver using a probe pulse. A lock-in amplifier set to the same frequency of the chopper is used to reduce noise in the signal detected by the transceiver. An image of the object may be created using the intensity or the timing of the peak amplitude of the terahertz pulses reflected from the object.

The invention discloses a shaping method of a difference frequency terahertz pulse and a shaping system thereof. In the shaping method, a laser pulse shaping device is used for realizing the programmable shaping of a laser pulse; two arrays of laser pulses passing through the converting and shaping device are regulated to be mutually vertical in polarization directions and then are overlaid in a non-linear crystal and subjected to difference frequency to generate a terahertz wave; and through controlling the wave forms and the phases of the two arrays of the laser pulses with mutually vertical polarization directions, the wave form and the electric field polarization direction of the generated terahertz pulse can be controlled and the wave form and the polarization direction of generated terahertz radiation can be detected. The invention not only can control the wave form and the pulse interval of the terahertz pulse, but also can control the electric field polarization direction of the terahertz pulse. Compared with a scheme for shaping the terahertz pulse by using a photoconductive antenna or through an optical rectification process, the invention has obvious advantages.

The utility model relates to a device and a method for detecting the particle concentration of the gas-solid flow based on the terahertz (THz) electromagnetic emission and detection device, comprising a femto-second laser, a coupling transmission optical fiber, a photoconductive antenna type THz electromagnetic emitter, an optical delay unit, an off-axis parabolic mirror, a THz detector, a phase-lock amplifier, a high-frequency power amplifier and a data acquisition and processing system controlled by a computer. The utility model reflects the THz wave sent from the THz electromagnetic emitter in parallel via the off-axis parabolic mirror and the THz wave through the gas-solid flow is condensed to the THz detector via the off-axis parabolic mirror. The particle concentration of the gas-solid flow on the section of a pipeline can be calculated with different models according to the measured THz time domain signal. The utility model has the advantages of simple structure, convenient installation, high measuring accuracy, safe use, and wide application in fields of petroleum, chemical industry, energy, metallurgy and environment.

The invention discloses a paper sheet quantitative detection device which is based on a terahertz time-domain spectroscopy technology and a method thereof. The detection device includes: a femtosecond laser, a beam splitter, an optical delay device, a reflective mirror, a focusing lens, a photoconductive antenna type terahertz transmitter, a polyethylene lens, a polarizer, a zinc telluride electro-optical crystal, a phase-locking amplifier, a high-power amplifier and a data collection and processing system. The invention makes use of the polyethylene lens for aligning the terahertz waves to the parallel light beams, and the polyethylene lens is used for focusing the terahertz waves on a terahertz detector after penetrating the paper sheet. The paper sheet quantitative detection method which is disclosed by the invention firstly establishes a paper sheet quantitative detection mathematical model, then respectively measures the time-domain signals of the terahertz waves penetrating the air and penetrating the paper sheet, extracts the delay time and applies the established mathematical model to calculate the paper sheet quantitative value. The invention has high precision of the measurement, strong anti-interference capability, small influence of multiple reflections and safe usage, so the invention can be used in the precise paper sheet quantitative detection of the field of paper making.

The invention provides a swill-cooked dirty oil detecting system. A semi-reflection and semi-transmission beam splitter is arranged at an emission port of a femtosecond laser; a pulse laser light is split into a pump light path and a detecting light path; the pump light path is connected with a photochopper, a first attenuation sheet, a first reflecting mirror, a second reflecting mirror, a first focusing lens and a gallium arsenide photoconductive antenna in sequence; a sample box is arranged on a confocal point of second and third paraboloidal mirrors; a second collimating lens, a half wave plate, a light path delay device, a third reflecting mirror, a polarizer and a high resistivity silicon reflecting mirror are arranged on the detecting light path in sequence; the femtosecond laser after being sampled by an electrooptic crystal is detected by being directed with a photoelectric detector via a quarter wave plate, a third focusing lens, a fourth reflecting mirror, a fourth focusing lens, a Wollstone prism as well as second and third attenuation sheets; and the variation of voltage magnitude caused by terahertz waves is recorded, so that a time domain terahertz signal including swill-cooked dirty oil information is obtained. The swill-cooked dirty oil detecting system provided by the invention has the advantages of simple detecting process, high efficiency, rapidness and accurate detecting result.

A photoconductor device and a method of manufacturing the same are provided. The photoconductor device includes a photoconductor substrate, a photoconductor thin film deposited on the photoconductor substrate, and a photoconductive antenna electrode formed on the photoconductor thin film. The photoconductor thin film includes polycrystalline GaAs.

The invention relates to nonlinear optical frequency conversion, and belongs to the interdisciplinary field of the terahertz radiation source technology and the optical frequency comb technology. For providing a terahertz frequency comb device based on optical rectification in a periodically poled crystal and a modulation method, and achieving an effect that the wide spectrum output is implemented in a range of 0.2-3.5 THz, a free spectrum range can reach 0.5 THz, and the device can run stably at room temperature, the invention adopts a technical scheme as follows: the terahertz frequency comb device based on the optical rectification in a periodically poled crystal is composed of a laser device, a periodically poled crystal and a receiving / detecting system, and a beam splitter and a glass convex lens are configured between the laser device and the periodically poled crystal; a polyethylene lens is arranged between the periodically poled crystal and a detector; generated THz waves areoutputted perpendicular to the side face of the crystal, and collected by the polyethylene lens; and the receiving / detecting system comprises a photoconductive antenna detector, a computer controllerand a delay line. The device and method provided by invention are mainly applied to nonlinear optical frequency conversion.

The invention relates to a terahertz photoconductive phased-array antenna system. The system comprises a laser source, an optical fiber coupler, a light delay controller and a terahertz photoconductive array antenna, wherein the optical fiber coupler is used for coupling the pump light generated by the laser source into an optical fiber; the light delay controller is used for controlling the delaying time of the pump light outputted by the optical fiber coupler and generating N beams of pump light at different delaying time; N is a natural number more than 1; the terahertz photoconductive array antenna is used for receiving the N beams of pump light at different delaying time outputted by the light delay controller; each beam of pump light is focused and irradiated on a corresponding bias antenna unit and then the terahertz irradiation is stimulated and generated. According to the terahertz photoconductive phased-array antenna system, the light delay controller is introduced into a pump light path of the photoconductive antenna array and the radiation phase is controlled so as to increase the radiation power of the array antenna and change the direction angle of the wave beam.

The invention discloses a terahertz wave generator based on graphene. The teraHertz wave generator comprises a substrate, a graphene film and a terahertz photoconductive antenna, wherein the graphene film is formed on the substrate and the terahertz photoconductive antenna is used for coupling Sierpinski fractal geometrical shape of the terahertz wave. According to the invention, bar-shaped electrodes are arranged at the two ends of inverse fractal antenna; a bias voltage is applied between the electrodes; the graphene film is pumped through femtosecond pulse laser; the electron motion in the graphene film is excited; the terahertz wave is irradiated under the effect of the bias voltage; the terahertz wave is coupled with the free space through the photoconductive antenna. Due to the high electronic mobility and the characteristic of easily generating terahertz wave of the graphene and the coupling function of the photoconductive antenna with similar characteristic, the emission efficiency of terahertz wave is increased, the antenna gain is increased, the power consumption and propagation loss of the antenna are reduced and the radiant power of the terahertz wave is increased.

The invention discloses a quick dynamic terahertz near field imaging system based on a photoconductive antenna array and a construction method thereof. The method comprises the following steps: preparing an optimized probe unit structural design; micro-processing and manufacturing the photoconductive antenna array; and carrying out gating activation on a probe array by using a spatial optical modulator and constructing a pulse terahertz imaging system. Compared with the prior art, the system and the method have the following advantages: (1) the quick dynamic terahertz near field imaging systembased on the photoconductive antenna array achieves the photoconductive antenna array which detects terahertz waves efficiently, and the resolution of the system is superior to lambda / 10 and the unitsignal-noise ratio is superior to 70 dB; and (2) the system carries out gating activation on the photoconductive antenna array by using the spatial optical modulator and combines a multichannel lockphase amplification technique, so that a dynamic, flexible, efficient and rapid data acquisition method is achieved.

Provided are a terahertz wave transmission and reception (Tx / Rx) module package and method of manufacturing the same. The complete and separate terahertz wave Tx / Rx module package is implemented by simply aligning a silicon ball lens, a photoconductive antenna and a focusing lens, and thus facilitates generation or measurement of a terahertz wave. The terahertz wave Tx / Rx module package and method can remarkably reduce time and cost required to build a terahertz wave generation and measurement system, and simplify and miniaturize the terahertz wave generation and measurement system. In addition, characteristics of a terahertz wave generated by the photoconductive antenna can be simply measured. Furthermore, the terahertz wave Tx / Rx module package can be stored and transported with a photoconductive antenna, a silicon ball lens and a focusing lens kept aligned as they are, and also it is possible to minimize pollution of terahertz wave devices caused by surroundings.

A system for detecting the burn degree of skin includes a laser source for generating laser light, a light-splitting device for splitting the laser light into a pump beam and a probe beam, a modulation device positioned on the optical path of the pump beam, a sampling device positioned between the light-splitting device and the modulation device, a terahertz pulse emitter for generating terahertz pulses by irradiating of the pump beam, a terahertz pulse detector for detecting the terahertz pulse reflected by a sample, a current detector electrically connected to the terahertz pulse detector, and a phase lock-in amplifier electrically connected to the current detector. The terahertz pulse emitter includes a plurality of photoconductive antennas positioned in an array manner, and the system further includes a first fiber coupler for transmitting the pump beam from the modulation device to the photoconductive antennas of the terahertz pulse emitter.

The invention provides an asynchronous optical sampling and double optical comb integrated terahertz wave spectrum system. The system includes a first femto second laser light source with an optical comb emitting pumped laser, a second femto second laser light source with an optical comb emitting detection laser, a first photo-conductive antenna, a terahertz wave gathering assembly and a second photo-conductive antenna, intervals of the pumped laser optical pump and the detection laser optical comb in the frequency domain are first predetermined repetition rate and second predetermined repetition rate respectively, a first offset voltage is applied to the first first photo-conductive antenna so that the first predetermined repetition rate is decreased to the terahertz frequency band to form a terahertz wave emitting optical comb, the terahertz wave gathering assembly transmits and gathers the terahertz wave optical comb to form a focus, the focus is positioned on the second photo-conductive antenna, and the terahertz wave emitting optical comb and the detection laser emitting optical comb generate RF-domain heterodyne optical comb signals by a multifrequency heterodyne process.

In a terahertz antenna module 1, a photoconductive antenna element 17 is fixed to a wiring board 9, and electrically connected to an electric signal input / output pin 24 of an electric signal input / output port 23 via a signal electrode of the wiring board 9. Further, a buffer member 7, a hemispherical lens 8, a photoconductive antenna element 17, and the wiring board 9 are disposed in a recess 3 of a container 2 in this order from an opening 6 side of the container 2, and by attaching a cover 25 to the container 2, the wiring board 9, the photoconductive antenna element 17, and the hemispherical lens 8 are pressed against the buffer member 7. Further, the wiring board 9 is positioned by the recess 4 and the hemispherical lens 8 is positioned by the buffer member 7 so that the optical axis OA of the hemispherical lens 8 passes just through a photoconductive antenna part of the photoconductive antenna element 17.

The embodiment of the invention provides a spinning electron terahertz wave emitter based on voltage-controlled magnetization. Based on a reverse spinning Hall effect, a pumping laser irradiates a multilayer film structure including an electrode film layer, an insulating film layer, a ferromagnetic film layer, and a non-ferromagnetic film layer to generate a broadband terahertz pulse. Based on a Rashba effect and a spining orbital theory, an in-plane out-of-plane magnetization ratio is changed by applying a controllable voltage to achieve a purpose of changing the output terahertz. The material forming the multilayer film structure is relatively low in cost, and the ferromagnetic film layer can be prepared on a large scale. Unlike the existing nonlinear crystal and photoconductive antenna,the antenna is greatly reduced in cost. The ferromagnetic film layer has perpendicular magnetic anisotropy, and thus achieves magnetization in unit area much higher than the in-plane magnetization.

A photoconductive antenna is adapted to generate terahertz waves when irradiated by pulsed light. The photoconductive antenna includes first and second conductive layers, a semiconductor layer positioned between the first and second conductive layers, first and second electrodes, and a dielectric layer. The semiconductor layer is made of a semiconductor material having a carrier density that is lower than a carrier density of the semiconductor material of the first conductive layer or the second conducive layer. The first and second electrodes are electrically connected to the first and second conductive layers, respectively. The second electrode has an aperture through which the pulsed light passes. The dielectric layer is made of a dielectric material, and is in contact with a surface of the semiconductor layer having a normal direction extending orthogonal to a lamination direction of the first conductive layer, the semiconductor layer, and the second conductive layer.

The invention discloses a terahertz OAM (Orbital Angular Momentum) generation system based on an optical mixing and fusion optical communication system. The terahertz OAM generation system includes two DFB (Distributed Feedback) lasers of which the frequency difference is in the terahertz band and which are used for generating optical communication wavelengths, a spatial light modulator which is used for modulating the orbital angular momentum of one channel of optical communication wavelength, a Mach-Zehnder modulator which is used for modulating the baseband electrical signal information ofthe other channel of optical communication wavelength, and a terahertz photoconductive antenna mixer which is used for beating the frequency of the combined optical signal to generate the terahertz band communication carriers of a modulated baseband signal carrying a certain order of orbital angular momentum. The frequency difference and phase difference transfer effects of the terahertz photoconductive antenna mixer are utilized to modulate the orbital angular momentum of one channel and the baseband electrical signal of the other channel without adding devices other than optical communication. The terahertz OAM generation system can be integrated with the current large-capacity optical communication system. By utilizing the frequency and phase transfer effects of photon mixing, the technical problems of OAM generation and channel multiplexing in the terahertz band can be solved.

The invention belongs to the technical field of terahertz wave detection, and especially relates to a terahertz near-field detector with high sensitivity. In view of the inconvenient adjustment of the current terahertz near-field detector, the following scheme is proposed: the terahertz near-field detector comprises a fixed shell; a first sliding groove is arranged on the inner wall of the bottom of the fixed shell, and the inner wall of one side of the first sliding groove is rotatably connected with a screw rod; the other end of the screw rod extends to the outside of the fixed shell; the outer wall of the circumference of the screw rod is connected with a lower sliding block in a sliding mode, and the outer wall of one side of the circumference of the screw rod is rotatably connected with a driven gear; and the outer wall of one side of the fixed shell is connected with a rotating shaft. According to the terahertz near-field detector with the high sensitivity provided by the invention, a hand wheel, a driving gear and the driven gear are arranged, so that a lower sliding block on the screw rod can be driven to move, so that the distance between a photoconductive antenna on a metal plate with a hole at the top of the lower sliding block and a silicon lens can be changed, therefore different positions of terahertz waves are imaged, thereby improving the working efficiency and facilitating the adjustment by people.

The invention relates to a multifunctional terahertz spectrum and imaging measurement module. The multifunctional terahertz spectrum and imaging measurement module comprises two electric control rotatable mechanical arms which are fixed on the same rotary center shaft and are arranged on the top surface of a module base, a module power supply and control interface arranged on a side face, a terahertz emission photoconductive antenna and a terahertz receiving photoconductive antenna which are fixed on the electric control rotatable mechanical arms, an electric control horizontal movable guide rail and an electric control vertical movable guide rail which are fixed on the rotary center shaft of the electric control rotatable mechanical arms, and a sample clamping device arranged in the middle of an electric control two-dimensional displacement platform which is composed of the electric control horizontal movable guide rail and the electric control vertical movable guide rail. The invention further relates to a transmission measurement method and a reflection measurement method of the multifunctional terahertz spectrum and imaging measurement module. The multifunctional terahertz spectrum and imaging measurement module provided by the invention has comprehensive functions, and is convenient to control, high in testing efficiency, compact in structure and easy to integrate in a common terahertz spectrum system.

The invention relates to a transwell detection device and method based on a terahertz attenuated total reflection technology. The transwell detection device and method can be used for conducting quickunmarked quantitative detection on cells on the lower layer of a transwell experimental cavity. The transwell detection device comprises a terahertz signal generation unit, a total reflection prism detection unit, a terahertz signal receiving unit, a time delay control system and a signal processing unit. The terahertz signal generation unit comprises a femtosecond laser light source, a laser beam splitter, a super-hemisphere Si-lens I and a photoconductive antenna I. The total reflection prism detection unit comprises a transwell cavity and a total reflection prism from top to bottom, a permeability porous thin film is arranged at the bottom of the transwell cavity, a unicellular layer is attached to the position under the porous thin film, and the unicellular layer makes close contact with the total reflection prism. The terahertz signal receiving unit comprises a photoconductive antenna II. The time delay control system comprises a time delay device.

A process of fabricating and a photoconductive antenna are disclosed which include a semi-insulating substrate having a top side and a bottom side; a low-temperature Gallium Arsenide (GaAs) layer deposited on the top side of the semi-insulating substrate; a plurality of metal electrodes having a bowtie dipole, with an excitation gap at the center, deposited directly on the low-temperature Gallium Arsenide layer; and an extended hemispherical lens attached to the bottom side of the semi-insulating substrate; the extended hemispherical lens further comprises an extension layer and a hemispherical layer separated by an extended line whose position is selected so that a beam of light coming from outside of the extended hemispherical lens is collimated to the excitation gap.

The invention provides a sub-wavelength structure based terahertz radiation modulated photo-conductive antenna and a preparation method thereof. The method comprises the following steps that 1) a GaAsfilm (2) is grown on the surface of a GaAs substrate (1); 2) a metal nanometer array (3) is grown on the surface of the GaAs film (2) according to a first preset pattern; 3) the surface of the GaAs film (2) is etched according to a second preset pattern, and titanium and gold are deposited successively to form an electrode (4); and 4) the electrode (4) is led out and packaged.

The invention relates to a terahertz near field probe, a photoconductive antenna and a manufacture method of the photoconductive antenna. The photoconductive antenna comprises a substrate, a low-temperature gallium arsenide wave plate layer bonded on the substrate, a dipole antenna bonded on the low-temperature gallium arsenide wave plate layer, an insulation layer arranged on the dipole antenna and a perforated metal plate arranged on the insulation layer, wherein the dipole antenna is a low-temperature gallium arsenide slice. Background noise signals can be remarkably attenuated by the perforated metal plate, and the spatial resolution of near field detection is increased.

The invention discloses a composite photoconductive antenna and a terahertz wave radiation source. The composite photoconductive antenna is characterized by comprising a photoconductor, a dipole antenna and a clamp electrode, the dipole antenna is positioned on the upper surface of the photoconductor and provided with a transverse structure, the clamp electrode is positioned on the lower surface of the photoconductor and forms a longitudinal structure with the dipole antenna, and two illumination areas are formed on the photoconductor. The composite photoconductive antenna has the advantages that switches with longitudinal structures are high in puncture voltage and flow capacity, the antenna with the transverse structure is simple to manufacture and the like, and the service life of the photoconductive antenna is prolonged. The terahertz wave radiation source charges the composite photoconductive antenna with a symmetric structure by the aid of a bridge circuit, the two longitudinal switches are synchronously triggered, energy consumption of the circuit is decreased, and terahertz waves are radiated at maximum efficiency.

In a terahertz antenna module 1, a photoconductive antenna element 17 is fixed to a wiring board 9, and electrically connected to an electric signal input / output pin 24 of an electric signal input / output port 23 via a signal electrode of the wiring board 9. Further, a buffer member 7, a hemispherical lens 8, a photoconductive antenna element 17, and the wiring board 9 are disposed in a recess 3 of a container 2 in this order from an opening 6 side of the container 2, and by attaching a cover 25 to the container 2, the wiring board 9, the photoconductive antenna element 17, and the hemispherical lens 8 are pressed against the buffer member 7. Further, the wiring board 9 is positioned by the recess 4 and the hemispherical lens 8 is positioned by the buffer member 7 so that the optical axis OA of the hemispherical lens 8 passes just through a photoconductive antenna part of the photoconductive antenna element 17.

The invention discloses a terahertz photoelectric conductive antenna array. The terahertz photoelectric conductive antenna array comprises an antenna matrix formed by N*N photoelectric conductive antenna array elements; each antenna array element is powered by one independent power supply apparatus separately; the antenna array elements are triggered synchronously by pumped light; and the terahertz waves emitted by all the antenna array elements are focused on the same point by a focusing optical element. By virtue of the terahertz photoelectric conductive antenna array, influence of an inverted bias electric field in the THz photoelectric conductive antenna array is eliminated, and the THz waves radiated by each antenna array element reach about 100% of synthesis degree, so that THz waveradiation strength and power of the photoelectric conductive antenna array are greatly reinforced; the THz waves radiated by each antenna array element are completely consistent in phases, and the synthesized waveform shapes and the waveforms radiated by each antenna array element are totally the same, without causing any influence to the spectral characteristics.

A photoconductive antenna that generates a terahertz wave by irradiation with a light pulse, includes: a first layer that has carriers formed therein by irradiation with the light pulse; a second layer, located above the first layer, which has carrier mobility larger than carrier mobility of the first layer; and a first electrode and a second electrode, located above the second layer, which apply a voltage to the second layer.

A semi-insulating GaAs photoconductive antenna with ohmic contact electrodes comprises a semi-insulating GaAs substrate which is provided with a positive AuGeNi alloy electrode and a negative AuGeNi alloy electrode; the semi-insulating GaAs substrate can be considered as a resistor RGaAs with high resistance; the two AuGeNi alloy electrodes can be considered as the resistors Rohm with lower resistance; the resistor RGaAs is connected with the resistors Rohm in serials; and Rohm << RGaAs. Breakdown electric field of the photoconductive antenna is increased through ohmic contact of the antenna electrodes, and meanwhile the whole gap between the electrodes is basically or totally covered by the electric field distribution of the antenna; and as intensity of photon-generated carriers of a unit area is decreased, coulomb screening effect and radiation-field screening effect are controlled effectively, and emitting efficiency of the antenna is increased. Compared with those of the traditional antennas, radiation efficiency and radiation power of the photoconductive antenna with the AuGeNi alloy ohmic contact electrodes are remarkably increased.