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Using optical-pump/THz-probe spectroscopy on gated, undoped graphene, we find that as the amplitude of the THz probe is increased, we observe a cross-over from optically-induced transmission decrease to increase.
Terahertz field-induced transmission enhancement in monolayer epitaxial graphene is observed with increasing terahertz field. Photoexcitation leads to further transmission enhancement that is found to be less for the higher terahertz field amplitudes.
General restrictions arising from gain-narrowing and phase-matching are circumvented by employing parametric amplification in the frequency rather than the time domain. Frequency-domain OPA has been used for amplifying few-cycle pulses and for high gain amplification.
We investigate the terahertz generation efficiency dependence as function of the pulse width durations at 800 nm. Our results confirmed conversion efficiency of 0.35% with saturation at 240 fs of pulse width duration.
We report temperature dependence and thermal hysteresis behavior of terahertz transmission through photoexcited graphene. We vary the temperature between room temperature and 1800°C, and use the optical-pump/terahertz-probe differential transmission technique.
We demonstrate self-referenced spectral-domain interferometry (SDI) for terahertz detection. It not only overcomes the limitation of over-rotation for intense terahertz fields, but also considerably increases the signal-to-noise ratio, when compared with conventional SDI techniques.
We present optical pump / high-power THz probe measurements for undoped silicon at different optical pump fluences. We observe an absorption bleaching of intense terahertz (THz) pulses, which decreases with increasing optical pump fluence.
We show that by employing positively chirped optical probe pulses above a critical power it is possible to enhance the detection bandwidth and signal obtained by Air Biased Coherent Detection scheme for broadband terahertz fields.
We report on the signal enhancement in the Air Biased Coherent Detection scheme of broadband terahertz fields in the transition from below to above the critical power for self-focusing of positively chirped optical probe pulses.
The nonlinear interaction of intense few-cycle terahertz pulses with free carriers in semiconductors is studied in both n-doped and photoexcited systems. Intervalley scattering is found to cause ultrafast modulation and bleaching of the terahertz absorption.
For an improvement of Jc under applied magnetic fields, an addition of BaZrO3 (BZO) nanorods into REBa2Cu3Oy(REBCO) films is actively discussed. However, the growth mechanisms of the BZO nanorods are still evidently unexplained. In this study, in order to control the growth of BZO nanorods in REBCO films, we fabricated the Sm1+xBa2-xCu3Oy (SmBCO) films containing BZO by conventional pulsed laser deposition...
We have performed open-aperture Z-scan measurements on n-doped InGaAs using intense few-cycle terahertz pulses. We observe a significant bleaching of the terahertz pulse absorption attributed to terahertz-electric-field-induced intervalley carrier scattering.
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