A reproducible terahertz （THz） photocurrent was observed at low temperatures in a Schottky wrap gate single electron transistor with a normal-incident of a CH3OH gas laser with the frequency 2.54THz. The change of s...A reproducible terahertz （THz） photocurrent was observed at low temperatures in a Schottky wrap gate single electron transistor with a normal-incident of a CH3OH gas laser with the frequency 2.54THz. The change of source-drain current induced by THz photons shows that a satellite peak is generated beside the resonance peak. THz photon energy can be characterized by the difference of gate voltage positions between the resonance peak and satellite peak. This indicates that the satellite peak exactly results from the THz photon-assisted tunneling. Both experimental results and theoretical analysis show that a narrow spacing of double barriers is more effective for the enhancement of THz response.展开更多
Recent advancements in high-energy terahertz(THz)sources,driven by powerful laser systems,now enable the generation of ultrashort THz pulses with energies up to several millijoules,spanning frequencies from 1 to 30 TH...Recent advancements in high-energy terahertz(THz)sources,driven by powerful laser systems,now enable the generation of ultrashort THz pulses with energies up to several millijoules,spanning frequencies from 1 to 30 THz.A key breakthrough is developing a reliable single-shot detection method,essential for measuring the electric field of these broadband,low-repetition-rate pulses,which is vital for exploring the complex dynamics of THz emission and studying extreme nonlinear material responses in this range.Existing detection methods have been limited to lower frequencies.Here,we introduce the first potentially single-shot-capable THz detection technique for capturing ultra-broadband waveforms.Utilizing a 1-μm-thick SiN detection chip,we exploit THz field-induced second harmonic generation to achieve real-time monitoring of THz waveforms with frequency content up to 30 THz.By adjusting the angle between the THz and optical probe beams,we can fine-tune the detection window for enhanced flexibility.Our novel THz detector is ideally suited for high-energy,low-repetition-rate sources,unlocking new frontiers in THz research.展开更多
A polysilicon separated CMOS Schottky barrier diode is designed and tested in this study.By replacing the shallow trench isolation（STI）of a ploy ring,the series resistances of Schottky diodes are reduced,leading to ...A polysilicon separated CMOS Schottky barrier diode is designed and tested in this study.By replacing the shallow trench isolation（STI）of a ploy ring,the series resistances of Schottky diodes are reduced,leading to an improvement in cut-off frequencies.The device structure is detailed and a device model is developed.Our analysis on the device shows that the cut-off frequency increases with the decreasing of the Schottky contact area.Based on this observation,the Schottky contact area is set to0.38×0.38μm^2,which is the minimum contact diffusion area allowed by the process flow.The distance between the anode and the cathode is also discussed.Diodes with different dimensions are fabricated and measured.Through extensive measurements,the optimum dimensions are obtained.Bondpads with a reduced area are used to improve the measurement accuracy.The measurement results show that these diodes can achieve a cut-off frequency of 1.5 THz.Thus,it is possible to use these diodes in THz detection.展开更多
We present an inexpensive technique to obtain a three-dimensional(3D) millimeter wave(MMW) and terahertz(THz) image using upconversion. In this work we describe and demonstrate a method for upconversion of MMW/THz rad...We present an inexpensive technique to obtain a three-dimensional(3D) millimeter wave(MMW) and terahertz(THz) image using upconversion. In this work we describe and demonstrate a method for upconversion of MMW/THz radiation to the visual band using a very inexpensive miniature glow discharge detector(GDD) and a silicon photodetector. We present MMW/THz upconversion images based on measuring the visual light emitting from the GDD rather than its electrical current. The results show better response time and better sensitivity compared to the electronic detection performed previously. Furthermore, in this work we perform frequency modulation continuous wave(FMCW) radar detection based on this method using a GDD lamp, with a photodetector to measure GDD light emission. By using FMCW detection, the range in addition to the intensity at each pixel can be obtained,thus yielding the 3D image. The GDD acts as a heterodyne mixer not only electronically but also optically. The suggested 3D upconversion technique using the GDD is simple and inexpensive and has better performance compared to other MMW/THz imaging systems suggested in the literature. This method provides minimum detectable signal power that is about 6 orders of magnitude better than similar plasma systems due to the very large internal signal gain deriving from the much smaller electrode separation and resulting in much higher plasma electric field.展开更多
Strong terahertz(THz)radiation provides a powerful tool to manipulate and control complex condensed matter systems.This review provides an overview of progress in the generation,detection,and applications of intense T...Strong terahertz(THz)radiation provides a powerful tool to manipulate and control complex condensed matter systems.This review provides an overview of progress in the generation,detection,and applications of intense THz radiation.The tabletop intense THz sources based on Ti:sapphire laser are reviewed,including photoconductive antennas(PCAs),optical rectification sources,plasma-based THz sources,and some novel techniques for THz generations,such as topological insulators,spintronic materials,and metasurfaces.The coherent THz detection methods are summarized,and their limitations for intense THz detection are analyzed.Applications of intense THz radiation are introduced,including applications in spectroscopy detection,nonlinear effects,and switching of coherent magnons.The review is concluded with a short perspective on the generation and applications of intense THz radiation.展开更多
文摘A reproducible terahertz （THz） photocurrent was observed at low temperatures in a Schottky wrap gate single electron transistor with a normal-incident of a CH3OH gas laser with the frequency 2.54THz. The change of source-drain current induced by THz photons shows that a satellite peak is generated beside the resonance peak. THz photon energy can be characterized by the difference of gate voltage positions between the resonance peak and satellite peak. This indicates that the satellite peak exactly results from the THz photon-assisted tunneling. Both experimental results and theoretical analysis show that a narrow spacing of double barriers is more effective for the enhancement of THz response.
基金supported by the Independent Research Fund Denmark(project THz-GRIP:2035-00365B).
文摘Recent advancements in high-energy terahertz(THz)sources,driven by powerful laser systems,now enable the generation of ultrashort THz pulses with energies up to several millijoules,spanning frequencies from 1 to 30 THz.A key breakthrough is developing a reliable single-shot detection method,essential for measuring the electric field of these broadband,low-repetition-rate pulses,which is vital for exploring the complex dynamics of THz emission and studying extreme nonlinear material responses in this range.Existing detection methods have been limited to lower frequencies.Here,we introduce the first potentially single-shot-capable THz detection technique for capturing ultra-broadband waveforms.Utilizing a 1-μm-thick SiN detection chip,we exploit THz field-induced second harmonic generation to achieve real-time monitoring of THz waveforms with frequency content up to 30 THz.By adjusting the angle between the THz and optical probe beams,we can fine-tune the detection window for enhanced flexibility.Our novel THz detector is ideally suited for high-energy,low-repetition-rate sources,unlocking new frontiers in THz research.
基金Supported by the National Natural Science Foundation of China(61401025)
文摘A polysilicon separated CMOS Schottky barrier diode is designed and tested in this study.By replacing the shallow trench isolation（STI）of a ploy ring,the series resistances of Schottky diodes are reduced,leading to an improvement in cut-off frequencies.The device structure is detailed and a device model is developed.Our analysis on the device shows that the cut-off frequency increases with the decreasing of the Schottky contact area.Based on this observation,the Schottky contact area is set to0.38×0.38μm^2,which is the minimum contact diffusion area allowed by the process flow.The distance between the anode and the cathode is also discussed.Diodes with different dimensions are fabricated and measured.Through extensive measurements,the optimum dimensions are obtained.Bondpads with a reduced area are used to improve the measurement accuracy.The measurement results show that these diodes can achieve a cut-off frequency of 1.5 THz.Thus,it is possible to use these diodes in THz detection.
基金North Atlantic Treaty Organization(NATO)Science for Peace and Security(SPS)Program(MD.SFPP984775)
文摘We present an inexpensive technique to obtain a three-dimensional(3D) millimeter wave(MMW) and terahertz(THz) image using upconversion. In this work we describe and demonstrate a method for upconversion of MMW/THz radiation to the visual band using a very inexpensive miniature glow discharge detector(GDD) and a silicon photodetector. We present MMW/THz upconversion images based on measuring the visual light emitting from the GDD rather than its electrical current. The results show better response time and better sensitivity compared to the electronic detection performed previously. Furthermore, in this work we perform frequency modulation continuous wave(FMCW) radar detection based on this method using a GDD lamp, with a photodetector to measure GDD light emission. By using FMCW detection, the range in addition to the intensity at each pixel can be obtained,thus yielding the 3D image. The GDD acts as a heterodyne mixer not only electronically but also optically. The suggested 3D upconversion technique using the GDD is simple and inexpensive and has better performance compared to other MMW/THz imaging systems suggested in the literature. This method provides minimum detectable signal power that is about 6 orders of magnitude better than similar plasma systems due to the very large internal signal gain deriving from the much smaller electrode separation and resulting in much higher plasma electric field.
基金This work was supported by the National Key R&D Program of China(No.2019YFC1711905)the National Natural Science Foundation of China(Grant Nos.11774243,11774246,and 6167513)+2 种基金the Youth Innovative Research Team of Capital Normal University(No.19530050146)the Capacity Building for Science&Technology Innovation Fundamental Scientific Research Funds(Nos.19530050170 and 19530050180)the Scientific Research Base Development Program of the Beijing Municipal Commission of Education.
文摘Strong terahertz(THz)radiation provides a powerful tool to manipulate and control complex condensed matter systems.This review provides an overview of progress in the generation,detection,and applications of intense THz radiation.The tabletop intense THz sources based on Ti:sapphire laser are reviewed,including photoconductive antennas(PCAs),optical rectification sources,plasma-based THz sources,and some novel techniques for THz generations,such as topological insulators,spintronic materials,and metasurfaces.The coherent THz detection methods are summarized,and their limitations for intense THz detection are analyzed.Applications of intense THz radiation are introduced,including applications in spectroscopy detection,nonlinear effects,and switching of coherent magnons.The review is concluded with a short perspective on the generation and applications of intense THz radiation.
