Browsing by Author "Chu, Wei-Chen"

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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
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