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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) - Dispersion and Ridge Width Effect in Terahertz Quantum Cascade Laser Combs
摘要： We systematically investigate the laser ridge width effect on comb operation of single plasmon waveguide quantum cascade lasers emitting around 4.2 THz. The total group velocity dispersion (GVD), including gain, waveguide, and material dispersions, is numerically evaluated for 6-mm-long lasers with ridge widths varying from 100 to 200 μm. The simulation reveals that the clamped gain dispersion strongly contributes to the total GVD and the laser with a 150-μm-wide ridge shows the flattest total GVD in the lasing range between 4.05 and 4.35 THz. The optimal ridge width of 150 μm for comb operation is also experimentally verified.
关键词： group velocity dispersion,frequency comb,quantum cascade laser,ridge width,terahertz
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 Detectors Based on Plasmonic Excitations in Double CdTe/CdMgTe Quantum Wells
摘要： Double CdTe/CdMgTe quantum wells modulation doped with Iodine were etched to fabricate grids with a period of 8 μm and a geometrical aspect ratio ((cid:2)) between 0.2 and 0.7. Etching removed only the well closer to the sample's surface. Transmission of terahertz radiation as a function of magnetic field (B) up to 10 T was measured at 2 K. The spectra show a single magnetoplasmon resonance (MPR) which position in B depends on (cid:2). A huge amplitude of MPR, comparable to that of the cyclotron resonance, allows us to propose such structures as tunable plasmonic terahertz detectors.
关键词： CdTe/CdMgTe quantum wells,terahertz detectors,plasmonic excitations,magnetoplasmon resonance
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) - Sub-terahertz Quantum-cascade Laser Source based on Difference-frequency Generation
摘要： Authors report a sub-terahertz monolithic semiconductor source based on a high power, long-wavelength quantum cascade laser. In order to obtain higher nonlinear susceptibility in the sub-terahertz frequency region, we design long wavelength dual-upper-state active region in which transition dipole moments are substantially increased. A fabricated device with distributed feedback grating produces nearly watt-level infrared output power, and as a result, it exhibits a peak output power of 18.5 μW at room temperature, around a frequency of ~700 GHz. Besides, the device produces an output power of 103 μW at 110 K.
关键词： dual-upper-state active region,monolithic semiconductor source,difference-frequency generation,sub-terahertz,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) - Terahertz Near-field Metasurfaces and Superfocusing
摘要： In this work, a near-field metasurface is designed to overcome diffraction limit and superfocus terahertz waves by elaborately arranging the proposed unit cells with super small electric sizes. The full width at half-maximum beam width reaches up to 0.067λ0 (free-space wavelength) at a distance of 0.073λ0 at 0.437 THz. The near-field metasurface is beneficial for subwavelength resolution imaging, photolithography, non-contact sensing, and other applications in the near field.
关键词： subwavelength resolution,terahertz,near-field metasurface,superfocusing
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) - Characterizing the accelerating mode of a dielectric-lined waveguide designed for terahertz-driven manipulation of relativistic electron beams
摘要： We report on the generation of a terahertz (THz) beam with a quasi-TEM01 mode by exploiting the interferometric recombination of two linearly polarized emitters in a combined spintronic source. The generated THz beam was used to characterize the accelerating mode of a dielectric-lined waveguide (DLW) to inform on the recent demonstration of relativistic electron beam manipulation achieved with this THz-driven DLW at the CLARA research facility at Daresbury Laboratory.
关键词： dielectric-lined waveguide,relativistic electron beams,spintronic source,quasi-TEM01 mode,terahertz
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 polarization splitter based on parallel-plate waveguide technology
摘要： In this work we present the first terahertz polarization splitter based on a parallel-plate waveguide (PPWG). The proposed structure consists of a stacked array of stainless steel plates with 0.8 mm spacing. The device is capable of splitting the two orthogonal polarization components (TM and TE) in a frequency range of 180 GHz to 500 GHz. This unique technology represents an example of an artificially birefringent material.
关键词： parallel-plate waveguide,TM and TE modes,birefringent material,polarization splitter,terahertz,PPWG
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) - Excitation and amplification of the unidirectionally propagating terahertz plasmon in a periodical graphene structure
摘要： The amplification of unidirectionally propagating plasmon modes excited by the incident terahertz wave in a periodical structure with an active graphene is studied theoretically. The amplification of propagating plasmon modes is due to radiative recombination in inverted graphene.
关键词： plasmon,radiative recombination,amplification,terahertz,graphene
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) - Research of Volume Free-Electron Laser with Photonic Crystal Structure for Operation in Sub-Terahertz Range
摘要： In this work, we present the results of the numerical optimization of volume free-electron laser based on the interaction between an electron beam and periodic structure of microwave photonic crystal. The optimization aims at the advancement of such device to the sub-terahertz frequency range. We show that the reduction of characteristic geometric dimensions allows increasing the working frequency of photonic crystal fundamental mode up to 12.5 GHz. Moreover, we observe the possibility to generate microwaves at the fifth harmonic of the fundamental frequency, namely f=62.5 GHz and obtain an output power level of about 3.6 kW.
关键词： electron beam,numerical optimization,sub-terahertz,volume free-electron laser,photonic crystal
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) - Intraband Ultrafast Terahertz Conductivity Dynamics in Graphene
摘要： The cooling mechanism is crucial for nanoelectronics, which determines the response time limited for the devices. The cooling process after optical pump in graphene, which is a well-known material with ultrahigh carrier mobility, is therefore an urgent research topic. Ultrafast thermalization and relaxation process in a monolayer graphene film grown on a quartz substrate is investigated by femtosecond laser pump, terahertz probe induced negative technique. A typical photo found, and the electron-phonon-impurity supercollision process is determined to about 2.8 picosecond at different pump photon energy and pump fluence. The competition between the impurity supercollision and the interband-intraband scattering in graphene could give new insight into the design of the application of graphene photonic devices.
关键词： ultrafast dynamics,cooling mechanism,electron-phonon-impurity supercollision,terahertz conductivity,graphene
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) - <sup>15</sup> NH <sub/>3</sub> terahertz gas laser pumped by a mid-infrared quantum-cascade laser
摘要： We present an optically pumped terahertz gas laser, which is based on a distributed-feedback mid-infrared quantum-cascade laser as a pump source, a standing wave resonator, and 15NH3 as a gain medium.
关键词： optical pumping,15NH3,terahertz gas laser,mid-infrared,quantum-cascade laser
更新于2025-09-16 10:30:52