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- 摘要
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Coherent Coupled-Mode Phonon Emission in a Photoexcited Charge-Density-Wave System
摘要： Photoexcitation the quasi-one-dimensional of charge-density-wave (CDW) system, blue bronze (K0.3MoO3), with near-infrared femtosecond pulses, results in both a low-frequency, broadband THz surface emission from the photo-Dember effect, and a narrow-band emission from a TO phonon doublet centered at 1.5 THz below ~100 K in the CDW state. The polarization dependence of the phonon emission leads us to propose a surface-field/quadrupole excitation mechanism, distinct from the typical mechanisms for phonon emission in other materials. A coupled-oscillator model with a transient suppression of the mode coupling can reproduce the detailed temporal and spectral characteristics of the emission.
关键词： charge-density-wave,photo-Dember effect,coupled-oscillator model,THz emission,coherent phonon emission
更新于2025-09-16 10:30:52
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Application of mosaicity induced disorder controlled rare earth nickelate thin films as THz transmission modulator
摘要： Here, we have studied mosaicity induced disorder (a unique type of disorder which is transferred from substrate template to film) controlled properties of rare earth nickelate thin films. While highly oriented film exhibits sharp metal to insulator transition (MIT) and Drude type of terahertz (THz) conductivity behavior, mosaic film exhibit much more subtle and broad transition and Drude-Smith type THz conductivity behavior. On the basis of such contrasting behavior, we propose application of these films as thermally controlled THz transmission modulator: oriented film as digital modulator while mosaic film as analog modulator.
关键词： metal to insulator transition,Drude-Smith model,rare earth nickelate,THz transmission modulator,mosaicity induced disorder
更新于2025-09-16 10:30:52
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Generation of a guided mode in a THz semiconductor waveguide using excitation by a tilted optical pulse front
摘要： We employ tilted-pulse-front techniques to control the propagation direction of the THz pulses emitted from photo-excited semiconductors. At a proper tilt angle of the optical pulse front, the generated THz pulse propagates along a waveguide on the semiconductor surface and eventually emits from the end facet of the semiconductor structure. This work aims at an investigation of semiconductor quantum structures with gain excited just in time when the THz pulse to be amplified arrives.
关键词： tilted optical pulse front,guided mode,THz,semiconductor waveguide
更新于2025-09-16 10:30:52
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Plasmonic nonlinearity in GaAs/In <sub/>0.20</sub> Ga <sub/>0.80</sub> As core/shell nanowires
摘要： We have investigated the plasmonic response of GaAs/In0.20Ga0.80As core/shell nanowires driven resonantly by strong THz fields with the amplitude of few MV/cm. The plasmon mode exhibits a systematic redshift with the suppression of the spectral weight with the increase of the driving THz field. Interestingly, the scaling of the plasmon parameters does not follow the usual quadratic behavior, indicating inhomogeneous intervalley electron scattering across the nanowire.
关键词： THz fields,intervalley electron scattering,GaAs/In0.20Ga0.80As,Plasmonic nonlinearity,core/shell nanowires
更新于2025-09-16 10:30:52
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - High power THz quantum cascade laser and its demonstration in high resolution holographic imaging
摘要： Fabrication of high power terahertz quantum cascade laser (THz QCL) based upon the resonant-phonon active region design and semi-insulating surface-plasmon waveguide with frequency at 4.4 THz and its demonstration in digital holographic imaging are presented. The maximum peak output power is 95mW at 10K in pulsed mode. The maximum working temperature is 80 K. Interestingly, by changing the injection current, the transverse mode of the laser can be switched between TM00 mode and TM01 mode. With such THz QCL as the light source, the lateral resolution of a home-built digital holographic imaging system can reach 80μm.
关键词： holographic imaging,high power,resonant-phonon,semi-insulating surface-plasmon waveguide,THz quantum cascade laser
更新于2025-09-16 10:30:52
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Milliwatt-Class MHz Repetition-Rate THz Source Driven by a sub-100 fs High Power Thin-Disk Laser
摘要： We demonstrate optical rectification in GaP crystals thin-disk oscillator, nonlinearly driven by a 100 W-class compressed to sub-100 fs in a multi-pass cell. In optimized conditions, we obtain a power of 1.35 mW, which is the highest average power achieved in GaP so far. Additionally, we explore the effect of temperature of the crystal down to 77 K, showing that controlling the temperature of the crystal could be a key aspect for further power scaling and for handling thermal effects that become important at such high driving powers.
关键词： thin-disk laser,optical rectification,THz source,GaP crystals,high power
更新于2025-09-16 10:30:52
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Frequency-and-polarization-controllable High-power THz Wave Generation Using Organic Nonlinear Optical Crystal
摘要： Arbitrary control of high-power THz polarization and frequency is studied by the numerical calculation based on the coupled wave approach. THz wave generation using organic crystals via optical rectification provides high conversion efficiency. To overcome the limitation of the generated THz field direction which comes from their optical anisotropy, we propose the synthesis of THz wave generated from two crystals whose optical axis are orthogonal each other. By the calculation, the linearly and circularly polarized THz wave generation by changing the time delay of two pump pulses is demonstrated.
关键词： optical rectification,organic nonlinear optical crystal,polarization control,frequency control,THz wave generation
更新于2025-09-16 10:30:52
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Advanced photoconductive Terahertz near-field microprobes for 1550 nm wavelength operation based on InGaAs:Rh
摘要： Photoconductive microprobes have been widely established for surface-near THz field measurements with sub-wavelength resolution and applications such as wafer scanning or metamaterial characterization. Since the standard material for these probes is still LT-GaAs, the optical pump wavelength is usually set below 890 nm for direct bandgap excitation. Adaption to modern fiber-based THz TDS systems – operating at 1550 nm – required the use of optical frequency doubling components, so far. In this work, we investigate an alternative solution based on InGaAs:Rh for direct operation at 1550 nm wavelength.
关键词： 1550 nm wavelength operation,THz near-field measurements,InGaAs:Rh,Photoconductive microprobes
更新于2025-09-16 10:30:52
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Terahertz Differential Absorption Spectroscopy Using Multi-Furcated Nd:YAG Microchip Laser for Gas Sensing
摘要： We demonstrate a frequency-domain differential absorption spectroscopy in the terahertz (THz) range for gas sensing applications. Our system is based on an injection-seeded THz-wave parametric generator driven by a multi-furcated Nd:YAG microchip laser. Within a single excitation cycle of the laser, the is-TPG generates up to three narrowband THz-wave pulses that are separated from each other in time by 78 μs and in frequency by 11 GHz, which is due to the spatial hole burning effect in the laser cavity. These pulses can be directly used to measure differential absorption signals, and first and second derivative spectra of target gas molecules without measuring reference spectra.
关键词： Nd:YAG microchip laser,gas sensing,differential absorption spectroscopy,THz-wave parametric generator,terahertz
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Realtime Coherent cw THz System: Phase Modulation without Phase Modulator
摘要： In optoelectronic continuous wave (cw) THz spectroscopy phase measurement is very beneficial, to improve SNR and/or to obtain depth information. Often, the required phase modulation limits the acquisition speed and increases the complexity of existing cw THz systems. Commonly, optical free space delay lines, fibre stretchers [1] or electro optical modulators [2] are used for phase modulation. In this paper we demonstrate that a simple optical fiber delay in combination with a fast sweeping laser source can be used for ultrafast fast phase modulation. With this technique we demonstrate a fully fibre-coupled cw THz spectrometer with 58 Hz update rate covering a bandwidth of 2.5 THz. To the best of our knowledge this is the fastest coherent cw THz system demonstrated so far. This makes cw THz systems competitive to time-domain approaches in terms of acquisition speed and simplifies the system architecture significantly. Therefore, it paves the way for compact, broadband and cost-effective THz systems.
关键词： continuous wave,phase modulation,fast sweeping laser,fiber delay,THz spectroscopy
更新于2025-09-16 10:30:52