The terahertz wave is considered to have great values and plentiful applications, such as in material science, analysis of molecular spectra, information and communication technology, biology and medical science, nond...The terahertz wave is considered to have great values and plentiful applications, such as in material science, analysis of molecular spectra, information and communication technology, biology and medical science, nondestructive evaluation, and national security. High-power widely tunable terahertz sources are required in the above practical applications of terahertz technologies. A promising approach for monochromatic terahertz generation is based on second-order nonlinear optical effect, e.g.展开更多
We present the generation of high-repetition-rate strong-field terahertz(THz)pulses from a thin 4-N,N-dimethylamino-4’-N’-methyl-stilbazolium 2,4,6-trimethylbenzenesulfonate(DSTMS)organic crystal pumped by an ytterb...We present the generation of high-repetition-rate strong-field terahertz(THz)pulses from a thin 4-N,N-dimethylamino-4’-N’-methyl-stilbazolium 2,4,6-trimethylbenzenesulfonate(DSTMS)organic crystal pumped by an ytterbium-doped yttrium aluminum garnet laser.The generated THz pulse energy reaches 932.8 nJ at 1 kHz repetition rate,with a conversion efficiency of 0.19%and a peak electric field of 819 kV/cm.At a repetition rate of 10 kHz,it is able to maintain a peak electric field of 236 kV/cm and an average THz power of 0.77 mW.The high-repetition-rate,strong-field THz source provides a convenient tool for the study of THz matter manipulation and THz spectroscopy.展开更多
We investigate a novel Smith–Purcell terahertz source. This device is composed of an electron gun, a cylindrical resonator, a metallic grating, and a collector. The characteristics of the Smith–Purcell terahertz sou...We investigate a novel Smith–Purcell terahertz source. This device is composed of an electron gun, a cylindrical resonator, a metallic grating, and a collector. The characteristics of the Smith–Purcell terahertz source are discussed with the help of three-dimensional particle-in-cell simulation. In this device, coherent and high-power Smith–Purcell radiation(SPR) at the terahertz frequency range can be produced for the reasonable parameters of charge energy and grating. Our results indicate that coherent SPR at 506.529 GHz with a power around 1000 W can be obtained for a grating of period l=0.3 mm operating at the beam energy E=50 keV and beam current I=10 A.展开更多
Computed tomography has been proven to be useful for non-destructive inspection of structures and materials. We build a three-dimensional imaging system with the photonically generated incoherent noise source and the ...Computed tomography has been proven to be useful for non-destructive inspection of structures and materials. We build a three-dimensional imaging system with the photonically generated incoherent noise source and the Schottky barrier diode detector in the terahertz frequency band （90–140GHz）. Based on the computed tomography technique, the three-dimensional image of a ceramic sample is reconstructed successfully by stacking the slices at different heights. The imaging results not only indicate the ability of terahertz wave in the non-invasive sensing and non-destructive inspection applications, but also prove the effectiveness and superiority of the uni-traveling-carrier photodiode as a terahertz source in the imaging applications.展开更多
Free-space strong-field terahertz(THz)pulses,generated via optical rectification of femtosecond lasers in nonlinear crystals,are pivotal in various applications.However,conventional Ti:sapphire lasers struggle to prod...Free-space strong-field terahertz(THz)pulses,generated via optical rectification of femtosecond lasers in nonlinear crystals,are pivotal in various applications.However,conventional Ti:sapphire lasers struggle to produce high-average-power THz sources due to their limited output power.While kilowatt ytterbium lasers are increasingly adopted,their application in THz generation faces challenges:low optical-to-THz conversion efficiency(attributed to long pulse duration and low energy)and crystal damage under high pumping power.Here,we report a high-average-power strong-field THz source using a lithium niobate crystal pumped by a 1030 nm,570 fs,1 mJ,50 kHz ytterbium femtosecond laser with tilted pulse front pumping(TPFP).By systematically optimizing TPFP implementations and comparing grating-and echelon-type configurations,we achieve a THz source with 64.5 mW average power at 42 W,50 kHz pumping,and focused peak electric field of 525 kV/cm at 0.83 mJ,1 kHz operation.Additionally,we observe Zeeman torque signals in cobalt-iron ferromagnetic nanofilms.This high-repetition-rate,high-average-power THz system,combined with its potential capabilities in high signal-to-noise ratio spectroscopy and imaging,promises transformative impacts in quantum matter manipulation,non-destructive testing,and biomedicine.展开更多
Strong-field terahertz waves not only have high peak power but also possess strong electromagnetic field components.When electrons encounters strong-field terahertz waves,a series of novel changes are induced,which ha...Strong-field terahertz waves not only have high peak power but also possess strong electromagnetic field components.When electrons encounters strong-field terahertz waves,a series of novel changes are induced,which have attracted extensive attention.This review first introduces common optical sources for strong-field terahertz emission,such as photoconductive antennas,optical rectification crystals,and air plasmas.Subsequently,recent applications of strong-field terahertz technology in material state modulation are presented,mainly including strong-field terahertz wave-driven hot carrier motion,coherent phonon control,spintronics,electron acceleration,and biomedicine.展开更多
The viability of the indium phosphide(InP)Gunn diode as a source for low-THz band applications is analyzed based on a notch-δ-doped structure using the Monte Carlo modeling.The presence of theδ-doped layer could enh...The viability of the indium phosphide(InP)Gunn diode as a source for low-THz band applications is analyzed based on a notch-δ-doped structure using the Monte Carlo modeling.The presence of theδ-doped layer could enhance the current harmonic amplitude(A0)and the fundamental operating frequency(f0)of the InP Gunn diode beyond 300 GHz as compared with the conventional notch-doped structure for a 600-nm length device.With its superior electron transport properties,the notch-δ-doped InP Gunn diodes outperform the corresponding gallium arsenide(GaAs)diodes with up to 1.35 times higher in f0 and 2.4 times larger in A0 under DC biases.An optimized InP notch-δ-doped structure is estimated to be capable of generating 0.32-W radio-frequency(RF)power at 361 GHz.The Monte Carlo simulations predict a reduction of 44%in RF power,when the device temperature is increased from 300 K to 500 K;however,its operating frequency lies at 280 GHz which is within the low-THz band.This shows that the notch-δ-doped InP Gunn diode is a highly promising signal source for low-THz sensors,which are in a high demand in the autonomous vehicle industry.展开更多
We propose a spatial diffraction diagnostic method via inserting a millimeter-gap double slit into the collimated terahertz beam to monitor the minute variation of the terahertz beam in strong-field terahertz sources,...We propose a spatial diffraction diagnostic method via inserting a millimeter-gap double slit into the collimated terahertz beam to monitor the minute variation of the terahertz beam in strong-field terahertz sources,which is difficult to be resolved in conventional terahertz imaging systems.To verify the method,we intentionally fabricate tiny variations of the terahertz beam through tuning the iris for the infrared pumping beam before the tilted-pulse-front pumping setups.The phenomena can be well explained by the theory based on the tilted-pulse-front technique and terahertz diffraction.展开更多
Resonant tunneling diodes（RTD）have the potential for compact and coherent terahertz（THz）sources operating at room temperature,but their low output power severely restricts their application in THz frequency range....Resonant tunneling diodes（RTD）have the potential for compact and coherent terahertz（THz）sources operating at room temperature,but their low output power severely restricts their application in THz frequency range.In this paper,two methods are adopted to increase the peak current of RTD for enhancing its output power.First,different metal contact systems（including Pt/Ti/Pt/Au and Au Ge/Ni/Au）for RTD contact are introduced,and a higher current of RTD with Pt/Ti/Pt/Au contact demonstrates the superior contact characteristic of Pt/Ti/Pt/Au contact system.Second,the double barrier structure（DBS）of RTD is well designed to further improve the characteristic of RTD,and a high peak current of 154 kA/cm^2 is achieved at room temperature.The improved peak current is very beneficial for increasing the output power of RTD oscillator.展开更多
文摘The terahertz wave is considered to have great values and plentiful applications, such as in material science, analysis of molecular spectra, information and communication technology, biology and medical science, nondestructive evaluation, and national security. High-power widely tunable terahertz sources are required in the above practical applications of terahertz technologies. A promising approach for monochromatic terahertz generation is based on second-order nonlinear optical effect, e.g.
基金supported by the National Key Research and Development Program of China(No.2022YFA1604401)the National Natural Science Foundation of China(Nos.12325409,62105346 and 12388102)+2 种基金the CAS Project for Young Scientists in Basic Research(No.YSBR-059)the Basic Research Project of the Shanghai Science and Technology Innovation Action Plan(No.20JC1416000)the Shanghai Pilot Program for Basic Research–Chinese Academy of Sciences,Shanghai Branch。
文摘We present the generation of high-repetition-rate strong-field terahertz(THz)pulses from a thin 4-N,N-dimethylamino-4’-N’-methyl-stilbazolium 2,4,6-trimethylbenzenesulfonate(DSTMS)organic crystal pumped by an ytterbium-doped yttrium aluminum garnet laser.The generated THz pulse energy reaches 932.8 nJ at 1 kHz repetition rate,with a conversion efficiency of 0.19%and a peak electric field of 819 kV/cm.At a repetition rate of 10 kHz,it is able to maintain a peak electric field of 236 kV/cm and an average THz power of 0.77 mW.The high-repetition-rate,strong-field THz source provides a convenient tool for the study of THz matter manipulation and THz spectroscopy.
基金National Natural Science Foundation of China(NSFC)(11275089,11375081)Natural Science Foundation of Shandong Province(ZR2011FQ001)
文摘We investigate a novel Smith–Purcell terahertz source. This device is composed of an electron gun, a cylindrical resonator, a metallic grating, and a collector. The characteristics of the Smith–Purcell terahertz source are discussed with the help of three-dimensional particle-in-cell simulation. In this device, coherent and high-power Smith–Purcell radiation(SPR) at the terahertz frequency range can be produced for the reasonable parameters of charge energy and grating. Our results indicate that coherent SPR at 506.529 GHz with a power around 1000 W can be obtained for a grating of period l=0.3 mm operating at the beam energy E=50 keV and beam current I=10 A.
基金Supported by the Hundred Talents Program of Chinese Academy of Sciencesthe National Basic Research Program of China under Grant No 2014CB339803+2 种基金the Major National Development Project of Scientific Instrument and Equipment under Grant No2011YQ150021the National Natural Science Foundation of China under Grant Nos 61575214,61574155,61404149 and 61404150the Shanghai Municipal Commission of Science and Technology under Grant Nos 14530711300,15560722000 and 15ZR1447500
文摘Computed tomography has been proven to be useful for non-destructive inspection of structures and materials. We build a three-dimensional imaging system with the photonically generated incoherent noise source and the Schottky barrier diode detector in the terahertz frequency band （90–140GHz）. Based on the computed tomography technique, the three-dimensional image of a ceramic sample is reconstructed successfully by stacking the slices at different heights. The imaging results not only indicate the ability of terahertz wave in the non-invasive sensing and non-destructive inspection applications, but also prove the effectiveness and superiority of the uni-traveling-carrier photodiode as a terahertz source in the imaging applications.
基金Scientific Research Innovation Capability Support Project for Young(ZYGXQNJSKYCXNLZCXMI3)National Key Research and Development Program of China(2022YFA1604402)+1 种基金National Natural Science Foundation of China(U23A6002,92250307)Open Project Program of Wuhan National Laboratory for Optoelectronics(2022WNLOKF006)。
文摘Free-space strong-field terahertz(THz)pulses,generated via optical rectification of femtosecond lasers in nonlinear crystals,are pivotal in various applications.However,conventional Ti:sapphire lasers struggle to produce high-average-power THz sources due to their limited output power.While kilowatt ytterbium lasers are increasingly adopted,their application in THz generation faces challenges:low optical-to-THz conversion efficiency(attributed to long pulse duration and low energy)and crystal damage under high pumping power.Here,we report a high-average-power strong-field THz source using a lithium niobate crystal pumped by a 1030 nm,570 fs,1 mJ,50 kHz ytterbium femtosecond laser with tilted pulse front pumping(TPFP).By systematically optimizing TPFP implementations and comparing grating-and echelon-type configurations,we achieve a THz source with 64.5 mW average power at 42 W,50 kHz pumping,and focused peak electric field of 525 kV/cm at 0.83 mJ,1 kHz operation.Additionally,we observe Zeeman torque signals in cobalt-iron ferromagnetic nanofilms.This high-repetition-rate,high-average-power THz system,combined with its potential capabilities in high signal-to-noise ratio spectroscopy and imaging,promises transformative impacts in quantum matter manipulation,non-destructive testing,and biomedicine.
基金supported by the National Natural Science Foundation of China(No.12204251)。
文摘Strong-field terahertz waves not only have high peak power but also possess strong electromagnetic field components.When electrons encounters strong-field terahertz waves,a series of novel changes are induced,which have attracted extensive attention.This review first introduces common optical sources for strong-field terahertz emission,such as photoconductive antennas,optical rectification crystals,and air plasmas.Subsequently,recent applications of strong-field terahertz technology in material state modulation are presented,mainly including strong-field terahertz wave-driven hot carrier motion,coherent phonon control,spintronics,electron acceleration,and biomedicine.
文摘The viability of the indium phosphide(InP)Gunn diode as a source for low-THz band applications is analyzed based on a notch-δ-doped structure using the Monte Carlo modeling.The presence of theδ-doped layer could enhance the current harmonic amplitude(A0)and the fundamental operating frequency(f0)of the InP Gunn diode beyond 300 GHz as compared with the conventional notch-doped structure for a 600-nm length device.With its superior electron transport properties,the notch-δ-doped InP Gunn diodes outperform the corresponding gallium arsenide(GaAs)diodes with up to 1.35 times higher in f0 and 2.4 times larger in A0 under DC biases.An optimized InP notch-δ-doped structure is estimated to be capable of generating 0.32-W radio-frequency(RF)power at 361 GHz.The Monte Carlo simulations predict a reduction of 44%in RF power,when the device temperature is increased from 300 K to 500 K;however,its operating frequency lies at 280 GHz which is within the low-THz band.This shows that the notch-δ-doped InP Gunn diode is a highly promising signal source for low-THz sensors,which are in a high demand in the autonomous vehicle industry.
基金the Science Challenge Project(No.TZ2016005)the NationalNatural Science Foundation of China(Nos.11827807,61905007,11520101003,and 11861121001)the Strategic Priority Research Programof the Chinese Academy of Sciences(No.XDB16010200)。
文摘We propose a spatial diffraction diagnostic method via inserting a millimeter-gap double slit into the collimated terahertz beam to monitor the minute variation of the terahertz beam in strong-field terahertz sources,which is difficult to be resolved in conventional terahertz imaging systems.To verify the method,we intentionally fabricate tiny variations of the terahertz beam through tuning the iris for the infrared pumping beam before the tilted-pulse-front pumping setups.The phenomena can be well explained by the theory based on the tilted-pulse-front technique and terahertz diffraction.
文摘Resonant tunneling diodes（RTD）have the potential for compact and coherent terahertz（THz）sources operating at room temperature,but their low output power severely restricts their application in THz frequency range.In this paper,two methods are adopted to increase the peak current of RTD for enhancing its output power.First,different metal contact systems（including Pt/Ti/Pt/Au and Au Ge/Ni/Au）for RTD contact are introduced,and a higher current of RTD with Pt/Ti/Pt/Au contact demonstrates the superior contact characteristic of Pt/Ti/Pt/Au contact system.Second,the double barrier structure（DBS）of RTD is well designed to further improve the characteristic of RTD,and a high peak current of 154 kA/cm^2 is achieved at room temperature.The improved peak current is very beneficial for increasing the output power of RTD oscillator.
