113 results about "Terahertz quantum cascade laser" patented technology

The invention relates to a tomography imaging system and method based on a terahertz quantum device. The system comprises a terahertz source part, a transmission convergence light path system, a rotary parallel scanning table and a terahertz signal detection part, wherein the terahertz source part comprises a terahertz quantum cascade laser, a drive power supply and a chopping fan; the transmission convergence light path system comprises a first off-axis parabolic mirror group and a second off-axis parabolic mirror group; and the terahertz signal detection part comprises a terahertz quantum well detector, a signal processing module and a phase-locked amplifier. The method comprises the following steps: the continuous terahertz waves emitted by the terahertz quantum cascade laser are modulated by the chopping fan and converged on a sample by one off-axis parabolic mirror group; the terahertz waves penetrate through the sample and are converged to the terahertz quantum well detector through the other parabolic mirror group to generate a response light current; the light current signal is converted into a voltage signal; the voltage signal is amplified by a low-noise amplifier; and the data is read by the phase-locked amplifier. According to the invention, the tomographic image information of the sample can be effectively obtained.

The present invention is directed to the integration of a quantum cascade laser with a hollow waveguide on a chip to improve both the beam pattern and manufacturability. By coupling the QCL output into a single-mode rectangular waveguide the radiation mode structure can be known and the propagation, manipulation, and broadcast of the QCL radiation can then be entirely controlled by well-established rectangular waveguide techniques. By controlling the impedance of the interface, enhanced functions, such as creating amplifiers, efficient coupling to external cavities, and increasing power output from metal-metal THz QCLs, are also enabled.

The invention provides a single-mode large-power THz quantum cascade laser (QCL) and a manufacturing technology thereof. The single-mode large-power THz QCL comprises a two-dimensional photonic crystal waveguide located on a center and a first order grating waveguide distributed around the two-dimensional photonic crystal waveguide. By using the single-mode large-power THz QCL of the invention, output power of the THz laser of the center area waveguide can be substantially increased; a single-mode narrow line width of the THz laser can be guaranteed; a working mode set by the laser is only fed back; a lateral high-order mode can be inhibited; a quality factor of a photonic crystal resonator can be increased simultaneously.

The invention discloses a terahertz wave band wireless transmitting and receiving device and a transmitting and receiving method thereof. The transmitting and receiving device comprises a transmitting terminal composed of a first cold head, a terahertz quantum-cascade laser and a first polyethylene window plate, an optical path part containing two off-axis parabolic mirrors and air and a receiving terminal composed of a second cold head, a terahertz quantum well detector and a second polyethylene window plate. The invention has the advantage that currently undistributed frequency range of electromagnetic wave is selected to transmit and receive electromagnetic wave, the absorption of the selected frequency point of electromagnetic wave by the air is relatively weaker, thus reducing the attenuation loss of terahertz wave during the transmission process; the semiconductor quantum-cascade laser which has high energy conversion efficiency and small volume, is easy to integrate, and can work for long time and perform mass production is adopted by the transmitting terminal; the semiconductor quantum well detector which has small volume, is stable and reliable and can perform mass production is adopted by the receiving terminal; and the adopted semiconductor laser and detector both can operate at high frequency, thus being suitable for future terahertz communication applications.

The invention provides a terahertz near-field imaging system and a terahertz near-field imaging method. The terahertz near-field imaging system comprises terahertz coherent light source module, an external light path module and a near-field probe module. A high-power terahertz quantum-cascade laser is adopted to generate high-power THz (terahertz) radiation, a near-field terahertz signal of a target is detected through a probe technique and a self-mixing effect of the laser, and accordingly a high-resolution-rate imaging function is realized. The terahertz near-field imaging system and the terahertz near-field imaging method have the advantages that the self-mixing effect is adopted to substitute for a near-field detector, so that a light path system is simple and compact; the near-field terahertz signal reflected by the near-field probe shares a light path with an incident signal, so that the terahertz near-field imaging system is high in precision and simple in structure, defects of a traditional near-field imaging technique are overcome remarkably, and development and application of a high-precision terahertz near-field imaging technique is promoted positively.

The invention relates to a manufacturing method of a semi-insulating surface plasma waveguide Terahertz quantum cascaded laser device. The manufacturing method at least comprises the steps that: a molecular beam epitaxy grows a lower contact layer, a multiple quantum well active region and an upper contact layer on a semi-insulating GaAs substrate in sequence; an upper electrode metal layer is manufactured on epitaxial materials through photoetching, metalizing and stripping; a photoresist covers the upper electrode metal layer, and the active region is etched to form a ridge structure; the photoresist covers the entire ridge structure, the parts from the uncovered region to the lower contact layer are etched; a lower electrode metal layer is manufactured on both sides of a ridge waveguide through photoetching, metalizing and stripping; and the substrate is thinned, a chip is cleaved and the packaging is completed. The etching of the ridge waveguide is carried out in two steps, the two steps of etching form two downward steps, and the lower electrode metal layer covers the second etched step and second etched side walls to achieve good electrical contact between the lower electrode metal layer and the lower contact layer. The manufacturing method reduces requirements on etching thickness precision and evenness of ridge waveguide manufacturing through adding one step of photoetching process, increases rate of finished products in device processing, and reduces transverse series resistance introduced by the contact layers.

The invention provides a transmission imaging device and method based on a tera-hertz quantum device. The transmission imaging device comprises a light source part, an optical path part and a detection part, wherein the light source part comprises a driving power supply, a first cold head, a first heat sink arranged in the first cold head, a tera-hertz quantum cascaded laser arranged on the first heat sink and a first polyethylene window arranged on the first cold head; the optical path part comprises a first off-axis parabolic mirror, a second off-axis parabolic mirror, a two-dimensional electric translation platform, a third off-axis parabolic mirror and a fourth off-axis parabolic mirror; and the detection part comprises a second cold head, a second polyethylene window arranged on the second cold head, a second heat sink arranged in the second cold head, a tera-hertz quantum trap detector arranged on the second head sink, a signal processing circuit, an oscilloscope and a computer. The device and the method have the advantages that: an adopted tera-hertz radiation source can work in the pulse mode; and due to the adoption of the tera-hertz quantum trap detector serving as a signal detector, the imaging speed of a system can be increased effectively, and the imaging quality can be enhanced.

The invention discloses a superconducting heterodyne integrated receiver with a terahertz quantum-cascade laser as a local oscillation source. The superconducting heterodyne integrated receiver comprises the terahertz quantum-cascade laser, a frequency mixer, a first intermediate frequency amplifier, a second intermediate frequency amplifier, a spectrometer, a convex lens and a wave beam splitter. Local oscillation reference signal wave beams output by the terahertz quantum-cascade laser are shaped by the convex lens, then the local oscillation reference signal wave beams and detected signals are coupled to the frequency mixer through the wave beam splitter wave beam splitter, the first intermediate frequency amplifier and the second intermediate frequency amplifier amplify intermediate frequency signals output by the frequency mixer, and the spectrometer analyzes output signals of the second intermediate frequency amplifier. The terahertz quantum-cascade laser, the convex lens, the wave beam splitter, the frequency mixer and the first intermediate frequency amplifier are arranged in a low-temperature vacuum environment which is 4K in temperature and achieved by the same vacuum dewar, any adjustable optical element for coupling the output signals of the terahertz quantum-cascade laser to the superconducting electronic frequency mixer is not needed, the structure is simple and compact, and integration and miniaturization are facilitated.

The invention discloses an edge emitting terahertz quantum cascade laser integrated with a wedge-shaped structure of a grating and a manufacturing method thereof. The edge emitting terahertz quantum cascade laser integrated with the wedge-shaped structure of the grating at least comprises a DBR (distributed bragg reflection) grating waveguide, a rectangular straight waveguide and a wedge-shaped waveguide which are connected sequentially, wherein one end of the wedge-shaped waveguide is a narrow end surface and the other end of the wedge-shaped waveguide is a wide end surface; the narrow end surface of the wedge-shaped waveguide is connected with the rectangular straight waveguide. According to the invention, due to adoption of the wedge-shaped waveguide structure, the gain area of the laser is enlarged, the output light power is improved, the far field light spot divergence angle of the laser is reduced, and the emergent light beam quality is improved; by virtue of a one-cascade DBR grating structure, the single longitudinal mode lasing is realized, the reflection of lasing light is provided, and a traditional end surface coating technology is replaced.

The invention provides a phase-locked system and method for a terahertz quantum cascading laser, and the phase-locked system comprises a terahertz light source module which is used for achieving the output of a terahertz signal; a terahertz signal down-conversion module which is connected with the terahertz light source module and is used for receiving a terahertz signal and generates a beat frequency signal of the terahertz signal; a phase-locked module which is connected with the terahertz signal down-conversion module and is used for receiving the beat frequency signal and generates a drive compensation signal, wherein the drive compensation signal is inputted to the terahertz light source module and is used for achieving the phase locking of the terahertz quantum cascading laser. According to the scheme of the invention, a terahertz quantum well detector is employed for down-conversion of the terahertz signal for the first time, and achieves the quick and accurate extraction of a frequency mixing signal. A multi-mode terahertz quantum well cascading laser is selected for replacing a conventional radio-frequency frequency multiplier chain terahertz local oscillator source, and the system achieves the down-conversion through a beat frequency signal, and remarkably reduces the construction difficulty and complexity of a phase-locked technological system.

The invention relates to a terahertz quantum cascade laser of a multiple-mode interface structure. The terahertz quantum cascade laser comprises a multiple-mode interference wave guiding structure. The multiple-mode interference wave guiding structure comprises a semi-insulating substrate, a buffer layer, a lower contact layer, an active region, an upper contact layer and an upper metal layer in the perpendicular direction from bottom to top in sequence, wherein the active region, the upper contact layer and the upper metal layer form a ridge type structure on the lower contact layer; lower metal layers are arranged on the two sides of the ridge type structure; the upper metal layer forms a multiple-mode wave guide and output wave guides through the wet etching method; the output wave guides are single-mode wave guides and located at the centers of the two ends of the multiple-mode wave guide, and the width of each output wave guide is smaller than that of the multiple-mode wave guide. The invention further relates to a manufacturing method of the THz QCL. By the adoption of the THz QCL of the multiple-mode interface structure and the manufacturing method of the THz QCL, the light-emitting power of the THz QCL can be increased, the quality of an emitted light beam is not reduced, collection efficiency is not reduced, the device is kept small, and cost is reduced.

The invention provides a high-speed modulation method and device for a terahertz quantum cascade laser. The device comprises a buffer amplifier, a T-shaped bias device connected with the output end of the buffer amplifier, and the terahertz quantum cascade laser connected with the output end of the T-shaped bias device. The high-speed modulation method for the terahertz quantum cascade laser can carry out high-speed modulation on the terahertz quantum cascade laser large in load, high in threshold voltage and large in drive current, ensure that modulation signals are loaded to the terahertz quantum cascade laser in a distortionless mode, and avoid distortion of impulse waveforms. The device is simple in structure, easy to operate and integrate and suitable for being applied to future THz communication.

The invention provides a terahertz wave rapid rotation scanning imaging system and method, and the system comprises a terahertz quantum cascading laser, an objective table, a transmission gathering optical path system, a terahertz quantum well detector, a signal collection processing module, a synchronous control module, and an image display module. The system employ the terahertz quantum cascading laser as the radiation source, employs the photoconduction-type terahertz quantum well detector as the detector, employs the self-designed rotating table and translation platform, a signal transmission gathering optical path and a signal collection processing module, completes the terahertz wave rapid rotation scanning imaging, and remarkably improve the imaging duration and effect. The system and method achieves the actual application of the technology of terahertz wave rapid rotation scanning imaging, successfully improves the imaging speed and effect, and is of great significance to the development and popularization of the technology of terahertz wave rapid rotation scanning imaging.

The invention relates to a circuit modeling and simulation method representing the terahertz quantum cascading laser device multimode effect. The method includes the steps of firstly, establishing a multimode velocity equation set representing carrier transportation characteristics inside a THzQCL active layer; secondly, establishing a physical equation model representing the multimode effect inside the THzQCL; thirdly, obtaining a corresponding equivalent circuit model through variable substitution and simplification; fourthly, establishing an equivalent circuit model representing the electrical characteristics of the input end of the THzQCL; fifthly, establishing an equivalent circuit model representing the luminous power characteristics of the output end of the THzQCL; sixthly, establishing a circuit macro model which comprises an electrical port and an optical power output port, and conducting photoelectric property simulation and output spectral property testing on the basis of the circuit macro model. By means of the circuit modeling and simulation method, the influences of the temperature on various photoelectric properties of the THzQCL can be tested, and imitation and simulation for the photoelectric property and the output multimode effect of the THzQCL can be supported and achieved.

The invention relates to an on-chip terahertz double-frequency comb device with RF injection modulation. The on-chip terahertz double-frequency comb device with RF injection modulation comprises a terahertz quantum cascade laser and T-shaped offset devices; the terahertz quantum cascade laser has two laser resonant cavities in the same water plane; each laser resonant cavity comprises an upper electrode and a gain medium; the two laser resonant cavities share one lower electrode, but work independently; the upper electrodes of the two laser resonant cavities are connected with positive electrodes of different RF sources and DC sources at the same time respectively through different T-shaped offset devices; the lower electrode of the two laser resonant cavities is connected with the negative electrodes of respective DC sources; an annular device is arranged between one T-shaped offset device and one RF resource; the annular device is connected with the spectrum analyzer through the low-noise amplifier; and the two laser resonant cavities are at a distance of 500-5000 microns. The on-chip terahertz double-frequency comb device with RF injection modulation can output optical modes stably, expand an output spectrum range and realize a terahertz waveband double-frequency comb spectrum.

The invention provides a terahertz quantum cascade laser system, which comprises a DC source, a T-type polarization device connected with the DC source, a circulator connected with one end of the T-type polarization device, a frequency detection device connected with one end of the circulator, a radio frequency source connected with the other end of the circulator and a laser connected with the other end of the T-type polarization device, wherein the T-type polarization device is used for providing a polarization signal to the laser, coupling a beat frequency signal of the laser, leading the beat frequency signal to the circulator, or superimposing the polarization signal and the radio frequency signal and inputting the superimposed signals to the laser; the circulator is used for isolating the radio frequency signal and the beat frequency signal; the frequency detection device is used for detecting the frequency of the beat frequency signal; the radio frequency source is used for providing a radio frequency signal with the frequency being the same as that of the beat frequency signal; and the laser is used for generating the beat frequency signal and wide-spectrum terahertz waves.The terahertz quantum cascade laser system and the gas identification system and method of the invention solve a problem that the terahertz quantum cascade laser in the prior art is narrow in spectrum range and cannot detect the characteristic spectrum of a detected gas sample quickly and accurately.

The invention provides a terahertz quantum level cascaded laser with integration of an absorption waveguide and a fabrication method of the terahertz quantum level cascaded laser. The terahertz quantum level cascaded laser comprises a semi-insulation GaAs substrate, a GaAs buffer layer, an n-type heavily-doping lower contact layer, an active region, an n-type heavily-doping upper contact layer, a first upper electrode metal layer, a second upper electrode metal layer and a lower electrode metal layer, wherein the GaAs buffer layer is arranged on the upper surface of the semi-insulation GaAs substrate, the n-type heavily-doping lower contact layer is arranged on the surface of the GaAs buffer layer, the active region is arranged on the surface of the n-type heavily-doping lower contact layer, the n-type heavily-doping upper contact layer is arranged on the surface of the active region, the first upper electrode metal layer and the second upper electrode metal layer are arranged on the surface of the n-type heavily-doping upper contact layer and are arranged at spacing distance of L, the second upper electrode metal layer is an upper electrode metal layer capable of high-waveguide loss after annealing, and the lower electrode metal layer is arranged on the surface of the n-type heavily-doping lower contact layer and on the two sides of the active region. With the terahertz quantum level cascaded laser with integration of the absorption waveguide and the fabrication method of the terahertz quantum level cascaded laser, provided by the invention, the problems that THz absorbers are discrete devices and the used materials are highly different from THz QCL so that the THz absorbers cannot be used in an on-chip integration system based on a THz OQL material in the prior art are solved.

The invention provides a difference frequency terahertz quantum cascade laser. The difference frequency terahertz quantum cascade laser comprises an active area, and the active area is located above asubstrate. The active area comprises multi-cycle bottom-up cascade quantum dot active layers, the quantum dot active layer in each cycle comprises a plurality of bottom-up InGaAs / InAlAs quantum well / barrier pairs and quantum dot insertion layers, one quantum dot insertion layer is inserted between every two InGaAs / InAlAs quantum well / barrier pairs, and each quantum dot insertion layer comprises astrain self-organized quantum dot InAs layer and a GaAs layer which is used for strain compensation. According to the difference frequency terahertz quantum cascade laser, the multi-cycle cascade quantum dot active layers are introduced, and based on the phonon bottleneck effect and the inhomogeneous broadening degree of quantum dots, the performance, such as power, conversion efficiency, tuningrange and threshold current density, of the difference frequency terahertz quantum cascade laser can be improved.

The invention discloses a quantum cascade laser (QCL) phase-locked system using a solid-state semiconductor source harmonic as a reference source. The QCL phase-locked system comprises a first wave beam separator, a second wave beam separator, a band-pass filter, a terahertz frequency mixer, an intermediate-frequency amplification unit and a phase-lock unit which are connected sequentially, wherein a terahertz QCL outputs a signal to the first wave beam separator, and a solid-state semiconductor source higher harmonic outputs a signal to the second wave beam separator; the first wave beam separator and the second wave beam separator couple the output signal of the terahertz QCL and the signal of the solid-state semiconductor source higher harmonic to the terahertz frequency mixer respectively, and the frequency mixer uses the solid-state semiconductor source higher harmonic as a phase-lock reference; an intermediate-frequency signal obtained after the frequency mixing of the terahertz frequency mixer is amplified via the intermediate-frequency amplification unit at first, and then conveyed to the phase-lock unit; and the phase-locked performs phase-lock processing on the intermediate-frequency signal, so as to realize the phase lock of the terahertz QCL.

A terahertz quantum cascade laser (THz-QCL) element operable at an unexplored frequency is obtained. A crystal of a nitride semiconductor is used to fabricate a repeated set of unit structures into a super lattice. Each unit structure includes a first barrier layer, a first well layer, a second barrier layer, and a second well layer disposed in this order. An energy level structure for electrons under a bias electric field has a mediation level, an upper lasing level, and a lower lasing level. The energy value of the mediation level is close to the energy value of either an upper lasing level or a lower lasing level, each belonging to either the unit structure or the other unit structure adjacent thereto, and is separated from the energy value of the other level by at least the energy value of a longitudinal-optical (LO) phonon exhibited by the crystal.

Quantum cascade lasers (QCLs), and methods of manufacture of QCLs, comprising an active portion. In some embodiments, the active portion can comprise: a plurality of tensiley strained quantum barrier layers, each comprising GayIn1-yAs; and a plurality of compressively strained quantum well layers, each comprising GaxIn1-xAs. In some embodiments, the active portion can comprise: a plurality of compressively strained quantum barrier layers, each comprising AlyIn1-yAs; and a plurality of tensiley strained quantum well layers, each comprising GaxIn1-xAs. The active portion can be grown on InP substrate.

A method for analog designing of an active area of an AlGaN / GaN terahertz quantum cascade laser relates to methods for analog designing of active areas of terahertz quantum cascade lasers. The method includes: firstly, determining parameters required in one-dimensional effective mass Schrodinger equation; secondly, solving the Schrodinger equation; thirdly, calculating delta E21, delta E32 and delta E1'3; fourthly, judging; fifthly, searching the optimum structure; and sixthly, outputting the structure. The active area consists of n periods, and each period consists of three barrier layers and three potential well layers. The method can be applied to designing of active areas of terahertz quantum cascade lasers, and has the advantages that the longitudinal optical phonon scattering principle and the tunneling principle are fully used while the optimum active area structure can be searched out.

The invention provides a single-mode tunable terahertz quantum cascade laser device structure and a manufacturing method. The single-mode tunable terahertz quantum cascade laser device structure at least comprises a semi-insulating GaAs substrate, a GaAs buffer layer, a first contact layer, an active area, a second contact layer, a first metal layer and a second metal layer. The active layer, the second contact layer and the first metal layer form a ridge structure on the first contact layer. The side face of the ridge structure is inclined relative to the end face. The ridge structure is cut into a first sub-ridge structure and a second sub-ridge structure through an interstitial structure in the length direction. By the adoption of the oblique waveguide structure, the transverse mode selection capacity can be improved; on the premise that device single transverse mode output is ensured, the device width is larger, the outgoing beam far-field divergence angle is decreased, the refractive index is changed by injecting current of different magnitudes into two waveguides of a coupled cavity structure THz QCL, the Vernier effect is utilized for achieving the tunable wavelength, and the wavelength tunable range of the single-mode tunable terahertz quantum cascade laser device structure is larger than that of an existing device structure changing the refractive index only through current injection.

The invention relates to a device for implementing a terahertz quasi-Gaussian parallel laser beam. The device includes a terahertz quantum cascade laser, an adjustment system movably mounted on a lowtemperature sample frame, an off-axis parabolic mirror mounted on the adjustment system, a movable variable aperture diaphragm arranged outside a cryogenic dewar and a movable terahertz array detectordisposed outside the cryogenic dewar, wherein the terahertz quantum cascade laser is connected with a driving power supply and emits terahertz divergent laser; the off-axis parabolic mirror collectsthe terahertz divergent laser and outputs terahertz quasi-parallel laser beam; the variable aperture diaphragm performs beam optimization on the terahertz quasi-parallel laser beam to form the terahertz quasi-Gaussian parallel laser beam; and the terahertz array detector represents the two-dimensional energy distribution of the terahertz quasi-parallel laser beam and calibrates the collimation ofthe terahertz quasi-parallel laser beam. The invention further relates to a method for implementing the terahertz quasi-Gaussian parallel laser beam. According to the device and method for implementing the terahertz quasi-Gaussian parallel laser beam, the terahertz quasi-Gaussian parallel laser beam which is stable, reliable and excellent in beam quality can be acquired.

The invention relates to a radio frequency modulation system and method of a terahertz quantum cascaded laser in a pulse mode. The system comprises a pulse source, a T-shaped biasing device, a radio frequency source and a frequency spectrum analyzer, wherein the pulse source is connected with the terahertz quantum cascaded laser via an electrode plate and drives the terahertz quantum cascaded laser to work in the pulse mode and generate a beat frequency signal of the laser in a longitudinal mode, the T-shaped biasing device is connected with the terahertz quantum cascaded laser via a microstrip line, the radio frequency source is connected with the T-shaped biasing device via a circulator and is used for generating a radio frequency signal with a set frequency, and the frequency spectrum analyzer is connected with the circulator. The system has important significance to broadband formation of the terahertz quantum cascaded laser in the pulse mode.

The invention provides a terahertz laser polarization modulation and demodulation device and a realization method thereof. The terahertz laser polarization modulation and demodulation device comprises a driving power supply, terahertz quantum cascaded laser devices, a first off-axis parabolic mirror, a linear polarization laser modulator, a second off-axis parabolic mirror, a terahertz quantum well detector, a current amplifier and an oscilloscope. The terahertz laser quantum cascaded laser devices are adopted to act as ideal linear polarization laser sources, and the selection characteristic of the terahertz quantum well detector for linear polarization laser is utilized so that the whole device does not require additional polarizers or depolarizers, the polarization extinction ratio of the device is great than 1000, and a communication system using the polarization modulation device is enabled to have excellent signal-to-noise ratio. Besides, a linear polaroid is rapidly rotated at a certain speed, and the periodic change of polarization direction is converted into the change of polarization light signals along with time so that speed of polarization modulation and demodulation can be fully met, rapid signal modulation and demodulation can be realized, and thus a wireless communication technological means based on polarization modulation and demodulation is provided for the terahertz frequency band.

The invention provides a terahertz sensor for surface plasma resonance. The terahertz sensor at least comprises a heavily doped semiconductor film comprising a first surface and a second surface opposite to the first surface, an optical waveguide coupling layer formed on the first surface of the heavily doped semiconductor film, a sensing chip which is formed on the second surface of the heavily doped semiconductor film and arranged in a sample channel and is in contact with molecules to be detected, a terahertz quantum cascade laser for emitting terahertz light to the optical waveguide coupling layer, and a terahertz detector for detecting the terahertz light. According to the terahertz sensor, terahertz laser is generated by a laser device, total reflection is generated on the surfaces of the optical waveguide coupling layer and the heavily doped semiconductor film, evanescent waves are generated at an interface, surface plasma waves are generated between the heavily doped semiconductor film and a molecule-sensitive film, and the evanescent waves and the surface plasma waves form resonance by adjusting incident light and resonance angles; the sensor can be used for detecting biomacromolecules at terahertz resonance frequency band.

The invention provides a terahertz spectrum detection system and an application method thereof. The terahertz spectrum detection system comprises a modulation module, a mode selection module, a detection optical path and a detection module, and is characterized in that the modulation module is used for coupling DC bias signals and radio frequency signals, the mode selection module performs single longitudinal mode signal output on the coupled modulated signals, the detection optical path performs optical path transmission on the single longitudinal mode signals, the detection module determines the response of a specific frequency point in the THz spectrum for the signals transmitted by the detection optical path and displaying the response, the modulation module outputs signals to the mode selection module, and the mode selection module is sequentially connected with the detection optical path and the detection module through an optical path; and the mode selection mode and the modulation module are controlled by the detection module. According to the invention, a THz QCL (Terahertz Quantum Cascade Laser) is taken as a spectrum light source, and direct sampling is performed on an broadened THz laser spectrum by adopting an external cavity technology and a non-coherent detection technology, so that a signal synchronous sampling mechanism is saved, the spectrum reconstruction speed is high, and remote THz spectrum detection in an open environment is achieved.

The invention discloses a method and device for generating an audio modulation THz wave, applicable to THz communication application in the future. In the method, a THz quantum cascade laser is taken as a radiation source, intensity modulation is carried out on the THz quantum cascade laser, and an audio signal is loaded onto the THz wave. The device comprises the THz quantum cascade laser taken as the radiation source and a modulation circuit thereof, wherein the modulation circuit comprises an audio signal amplifying circuit, an audio signal and direct current bias signal superposing circuit and a superposed signal power amplifying circuit. By adopting the method and device disclosed by the invention, a modulation THz wave in a frequency band of 2-7THz can be generated, wherein the frequency band is not allocated or applied at present; and the adopted THz quantum cascade laser has high energy conversion efficiency, a small volume and easiness in integration and can be produced in a large scale.

The invention discloses a wet etching method for a ridge structure of a terahertz quantum cascade laser characterized by firstly producing an etching mask and a hardener by means of lithography development, then removing the oxide film on the material surface of the device by diluted hydrochloric acid, furthermore fixing and putting the corresponding clamp for the device material in a vessel containing a diluent sulfuric acid etching solution, wet etching the solution by a magnetic stirring apparatus, quickly taking out the device material from the etching solution after erosion, washing the material by excessive deionized water, blowing the material to dryness by high purity nitrogen, ensuring the erosion depth by means of ellipsometer after removing the surface photo-resist mask in an acetone solution with the device material in, thereby the erosion is convenient and fast and the erosion depth can be more easily to control because of low erosion speed, specially under the conditions of large erosion depth and long erosion time, the advantage seems particularly outstanding.