95 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 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 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.

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.

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.

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 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.

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.