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We discuss the possibilities of microring resonator based frequency comb sources for applications to THz-wave generation. Numerical simulations were performed using the Lugiato-Lefever model, combined with fully vectorial modal analyses, to investigate how the cavity design impacts the coherence properties of the combs and to quantitatively estimate the power conversion efficiency from the pump to...
A physical mechanism is presented which can generate coherent and tunable terahertz (THz) radiation. Due to the dramatical lifting of SPPs energy, the dispersion can cross the light line, thus, the SPPs excited by an moving electron beam can be transformed into THz radiation. The radiation power density is enhanced nearly three orders, up to 105 W/cm2. The radiation frequency can be widely tuned by...
Surface Plasmon Polariton Light Radiation Source (SPCLS) combines electronics and photonics to generate coherent, enhanced and tunable radiation ranging from terahertz to ultraviolet. To further improve its performance, an extension structure of SPCLS (ESPCLS) is proposed: two silver films with different thickness are deposited on two dielectric substrates to establish a new unsymmetrical structure...
We present a nonuniform metasurface that operates as a flat lens at 400 GHz. Efficiency is enhanced by the use of a novel, tri-layer polarization-converting nonuniform meta-surface structure. The device is fabricated and experimentally characterized. The results confirm that the flat lens is indeed capable of focusing radiation to a focal spot with ∼68% efficiency. Constrained by spatial dispersion,...
We present a simple analytical model for the dispersion of a pulse radiated by a self-complementary logarithmic-periodic antenna. The model predicts the variation in the spectral phase, and explains the underlying mechanism behind it. The variation in the spectral phase predicted by the model is compared with the spectral phase measured with a Terahertz (THz) Time Domain System (TDS) System that uses...
Graphene has been shown to be capable of supporting surface plasmon polaritons whose frequency is in the terahertz regime. We demonstrate that, due to the enhanced energy of surface plasmon in graphene, an optical bistability can occur in an air-graphene-dielectric structure.
“Hot” dispersion equations of axisymmetric TM mode of a coaxial double-grating slow-wave structure (SWS) with an annular beam is obtained. Utilizing field matching method, in which the higher order terms of the field in the grooves are considered, the solution for the small signal gain is given. The beam is regarded as a moving anisotropic medium with an effective permittivity constant.
A 0.38THz Traveling Wave Tube (TWT) based on the sine waveguide and sheet beam tunnel is proposed to amplify the terahertz wave. In this paper, the high frequency characteristics of sine waveguide with sheet beam tunnel are calculated by 3-D high frequency simulation software. From the particle-in-cell simulation results, this beam-wave interaction can produce output power 13W at 0.38THz, and the...
A Mid-Infrared spectrometer specifically suitable for non-cyclic or slow cycling processes was developed for microsecond time-resolved measurements. The spectrometer overcomes the limit of conventional time-resolved Fourier-transform techniques such as step-scan FTIR which require cyclic systems where the reaction cascade is to be triggered thousands of times and in quick succession. In our approach,...
We examined the effect of material dispersion in nonlinear crystals, waveplate, and plasma to the generation efficiency of ultrabroadband coherent infrared pulses from two-color pumped air plasma. We attribute the mechanism for intensity enhancement, which enabled the coherent detection over the frequency range of 1–200 THz, to the optimized polarization, group delay, and minimized dephasing between...
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