Browsing by Author "Ku, ML"

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A complementary codes pilot-based transmitter diversity technique for OFDM systems
(2006-03-01)
Ku, ML
;
Huang, CC
;
電信工程研究所
;
Institute of Communications Engineering
This letter presents a complementary codes pilot-based space-time block code/orthogonal frequency division multiplex (STBC/OFDM) system. In this system, a pair of complementary codes transmitted in a pre-defined order with the OFDM data signals is used as the pilot signals in a two-antenna transmitter diversity system, and used to estimate the channels for optimal data detection at the receiver side. A complete receiver architecture has been designed and Monte Carlo simulations have been used to verify the performance of the system in mobile radio fading channels.
Diode-pumped passively Q-switched picosecond Nd : GD(x)Y(1-x)VO(4) self-stimulated Raman laser
(2004-10-01)
Chen, YF
;
Ku, ML
;
Tsai, LY
;
Chen, YC
;
電子物理學系
An efficiency of 8.2% is demonstrated for a diode-pumped passively Q-switched self-stimulated Raman laser with an a-cut mixed vanadate crystal, Nd:Gd0.8Y0.2VO4. At 2.2 W of incident pump power, the self-stimulated Raman laser produces pulses as short as 660 ps at a Stokes wavelength of 1175 nm with 2.7 muJ of energy per pulse at a 66-kHz repetition rate. (C) 2004 Optical Society of America.
High-power efficient tunable Nd : GdVO4 laser at 1083 nm
(2005-08-15)
Chen, YF
;
Ku, ML
;
Su, KW
;
電子物理學系
;
Department of Electrophysics
An efficient tunable diode-pumped Nd:GdVO4 laser at 1083 nm has been constructed by suppressing the higher gain transition near 1063 nm. With 12.5 W diode pump power, the free-running output power centered about 1083 nm was up to 3.4 W, corresponding to an optical-to-optical conversion efficiency of 30.1%. When a simple uncoated etalon was used as a wavelength-selective element, the output power at each helium transition was higher than 2.5 W. (c) 2005 Optical Society of America.
InAs/GaAs quantum-dot saturable absorbers for diode-pumped passively Q-switched Nd-doped 1.3-mu m lasers
(2005-03-01)
Lai, HC
;
Li, A
;
Su, KW
;
Ku, ML
;
Chen, YF
Received August 6, 2004 A low-loss semiconductor saturable absorber based on InAs/GaAs quantum dots was developed for Q switching of a diode-pumped Nd-doped laser operating at 1.3 mum. With an InAs/GaAs quantum-dot saturable absorber, a diode-pumped Nd:YVO4 laser at 1342 nm. was achieved. With an incident pump power of 2.2 W, an average output power of 360 mW with a Q-switched pulse width of 90 ns at a pulse repetition rate of 770 kHz was obtained. (C) 2005 Optical Society of America