Browsing by Author "Andreev, Yu. M."

Now showing 1 - 6 of 6

Optical properties of nonlinear solid solution GaSe(1-x) S (x) (0 < x a parts per thousand currency signaEuro parts per thousand 0.4) crystals
(2008-10-01)
Ku, S. -A.
;
Luo, C. -W.
;
Lio, H. -L.
;
Wu, K. -H.
;
Juang, J. -Y.
Transmission spectra and phase matching conditions for second harmonic generation in GaSe(1-x) S (x) (0 < x a parts per thousand currency signaEuro parts per thousand 0.4) solid solution crystals are experimentally investigated. An algorithm is suggested and dispersion equations are derived that allow the phase matching angles describing best the available experimental data to be estimated as a function of the mixing ratio x.
Optical properties of nonlinear solid solution GaSe1-x S (x) (0 < x a parts per thousand currency signaEuro parts per thousand 0.4) crystals
(2008-10-01)
Ku, S. -A.
;
Luo, C. -W.
;
Lio, H. -L.
;
Wu, K. -H.
;
Juang, J. -Y.
Transmission spectra and phase matching conditions for second harmonic generation in GaSe1-x S (x) (0 < x a parts per thousand currency signaEuro parts per thousand 0.4) solid solution crystals are experimentally investigated. An algorithm is suggested and dispersion equations are derived that allow the phase matching angles describing best the available experimental data to be estimated as a function of the mixing ratio x.
Optimal Te-doping in GaSe for non-linear applications
(2012-02-27)
Ku, Shin An
;
Chu, Wei-Chen
;
Luo, Chih Wei
;
Andreev, Yu. M.
;
Lanskii, Grigory
Centimeter-sized Te-doped GaSe ingots were grown from the charge compositions of GaSe with nominals 0.05, 0.1, 0.5, 1, and 3 mass% Te, which were identified as e -GaSe: Te (0.01, 0.07, 0.38, 0.67, and 2.07 mass%) single crystals. The evolution of the absorption peaks of the phonon modes E'((2)) (similar to 0.584 THz) and E"((2)) (1.77 THz) on Te-doping in GaSe: Te crystals was studied by THz time-domain spectroscopy. This study proposes that the evolution of both E'((2)) and E"((2)) absorption peaks correlates well with the optical quality of Te-doped GaSe crystals, which was confirmed by experimental results on the efficiency of THz generation by optical rectification. Maximal intensity of the absorption peak of the rigid layer mode E'((2)) is proposed as a criterion for identification of optimal Te-doping in GaSe crystals. (C) 2012 Optical Society of America
Snapshots of Dirac Fermions near the Dirac Point in Topological Insulators
(2013-12-01)
Luo, C. W.
;
Wang, H. J.
;
Ku, S. A.
;
Chen, H. -J.
;
Yeh, T. T.
The recent focus on topological insulators is due to the scientific interest in the new state of quantum matter as well as the technology potential for a new generation of THz optoelectronics, spintronics and quantum computations. It is important to elucidate the dynamics of the Dirac fermions in the topologically protected surface state. Hence we utilized a novel ultrafast optical pump mid-infrared probe to 4 explore the dynamics of Dirac fermions near the Dirac point. The femtosecond snapshots of the relaxation process were revealed by the ultrafast optics. Specifically, the Dirac fermion-phonon coupling strength in the Dirac cone was found to increase from 0.08 to 0.19 while Dirac fermions were away from the Dirac point into higher energy states. Further, the energy-resolved transient reflectivity spectra disclosed the energy loss rate of Dirac fermions at room temperature was about 1 meV/ps. These results are crucial to the design of Dirac fermion devices.
Study of GaSe1-xSx Properties for Terahertz Applications
(2009)
Sarkisov, S. Yu.
;
Andreev, Yu. M.
;
Atuchin, V. V.
;
Morozov, A. N.
;
Kazakov, A. V.
For prospective nonlinear crystals GaSe1-xSx experimental study of second harmonic generation processes of Er3+:YSGG-, CO2- and CO-lasers has been performed, control experiment on difference frequency generation of two lines Of CO2-laser has been realized, the transmission spectra and dispersion of complex refractive indices in terahertz range have been measured.
Widely linear and non-phase-matched optical-to-terahertz conversion on GaSe:Te crystals
(2012-03-01)
Chu, Wei-Chen
;
Ku, Shin An
;
Wang, Harn Jiunn
;
Luo, Chih Wei
;
Andreev, Yu. M.
We demonstrate the widely linear and broadband terahertz (THz) generation on GaSe:Te crystals by femtosecond laser pulses. It was found that the dopant, Te atoms, in GaSe crystals significantly enhances the efficiency of THz generation, and its central frequency can be tuned by varying the crystal thickness through non-phase-matched optical rectification. Moreover, the wide-ranging linearity for the optical-to-THz conversion and central-frequency-tunable THz generation promise for GaSe: Te crystals to be potential materials for high-power (> 1.36 mu W) THz applications. (C) 2012 Optical Society of America