Browsing by Author "Chang, Y. T."

Now showing 1 - 12 of 12

AlGaInAs intracavity selective absorber for an efficient high-power Nd : YAG laser operation at 1.44 mu m
(2008-07-01)
Huang, Y. P.
;
Chang, Y. T.
;
Su, K. W.
;
Chen, Y. F.
;
Huang, K. F.
We develop an AlGaInAs material as a promising intracavity selective absorber for an efficient high-power Nd:YAG laser at 1.44 mu m. With the ISA to suppress operation at 1.06 mu m, the output coupler at 1.44 mu m can be straightforwardly designed and optimized. At a pump power of 16 W an output power of 2.5 W at 1.44 mu m, with a slope efficiency of 23%, was achieved. (C) 2008 Optical Society of America.
Compact efficient eye-safe intracavity optical parametric oscillator with a shared cavity configuration
(2007-06-10)
Chen, Y. F.
;
Su, K. W.
;
Chang, Y. T.
;
Yen, W. C.
;
電子物理學系
We present a compact efficient eye-safe intracavity optical parametric oscillator pumped by a passively Q-switched Nd:YAG laser in a shared cavity configuration. A signal pulse of 3.3 mJ energy at a 1573 nm wavelength with a peak power of 150 kW was achieved. The effective conversion efficiency with respective to the optimized 1064 nm Q-switched pulse energy was as high as 51%. (C) 2007 Optical Society of America.
Compact efficient Q-switched eye-safe laser at 1525 nm with a double-end diffusion-bonded Nd:YVO(4) crystal as a self-Raman medium
(2009-03-16)
Chang, Y. T.
;
Su, K. W.
;
Chang, H. L.
;
Chen, Y. F.
;
電子物理學系
We report on an efficient Q-switched eye-safe laser at 1525 nm with a double-end diffusion-bonded Nd:YVO(4) crystal as a self-Raman gain medium. A diffusion-bonded crystal not only reduces the thermal effects but also increase the interaction length for the stimulated Raman scattering. With an input pump power of 17.2 W, average power of 2.23 W at the first-Stokes wavelength of 1525 nm is generated at a pulse repetition rate of 40 kHz, corresponding to a conversion efficiency of 13%. (C) 2009 Optical Society of America
Compact efficient Q-switched eye-safe laser at 1525 nm with a double-end diffusion-bonded Nd:YVO4 crystal as a self-Raman medium
(2009-03-16)
Chang, Y. T.
;
Su, K. W.
;
Chang, H. L.
;
Chen, Y. F.
;
電子物理學系
We report on an efficient Q-switched eye-safe laser at 1525 nm with a double-end diffusion-bonded Nd:YVO4 crystal as a self-Raman gain medium. A diffusion-bonded crystal not only reduces the thermal effects but also increase the interaction length for the stimulated Raman scattering. With an input pump power of 17.2 W, average power of 2.23 W at the first-Stokes wavelength of 1525 nm is generated at a pulse repetition rate of 40 kHz, corresponding to a conversion efficiency of 13%. (C) 2009 Optical Society of America
Comparison of thermal lensing effects between single-end and double-end diffusion-bonded Nd:YVO(4) crystals for (4)F(3/2)->(4)I(11/2) and (4)F(3/2)->(4)I(13/2) transitions
(2008-12-08)
Chang, Y. T.
;
Huang, Y. P.
;
Su, K. W.
;
Chen, Y. F.
;
電子物理學系
The effective focal lengths of thermal lens in diode-end-pumped continuous-wave Nd:YVO(4) lasers for the (4)F(3/2)->(4)I(11/2) and (4)F(3/2)->(4)I(13/2) transitions were determined. The experimental results revealed that the thermal lensing effect for the (4)F(3/2)->(4)I(11/2) transition can be sufficiently improved by employing a single-end diffusion-bonded Nd: YVO4 crystal replacing a conventional Nd: YVO4 crystal. However, using a double-end diffusion-bonded Nd: YVO4 crystal was a great improvement over a single-end diffusion-bonded Nd: YVO4 crystal for the (4)F(3/2)->(4)I(13/2) transition with stronger thermal lensing effect. (C) 2008 Optical Society of America
Diode-pumped multi-frequency Q-switched laser with intracavity cascade Raman emission
(2008-05-26)
Chang, Y. T.
;
Huang, Y. P.
;
Su, K. W.
;
Chen, Y. F.
;
電子物理學系
A diode-pumped actively Q-switched mixed Nd:Y0.3Gd0.7VO4 laser with an intracavity KTP crystal is developed to produce cascade SRS emission up to the fourth order. With an incident pump power of 14 W and a repetition rate of 50 kHz, the average output powers at the first, second, third and fourth Stokes modes are approximately 0.05 W, 0.61 W, 0.25 W, and 0.11 W, respectively. The maximum peak power is greater than 2 kW. (C) 2008 Optical Society of America.
Experimental evidence for a two-gap structure of superconducting NbSe(2): A specific-heat study in external magnetic fields
(2007-12-01)
Huang, C. L.
;
Lin, J. -Y.
;
Chang, Y. T.
;
Sun, C. P.
;
Shen, H. Y.
To resolve the discrepancies of the superconducting order parameter in quasi-two-dimensional NbSe(2), comprehensive specific-heat measurements have been carried out. By analyzing both the zero-field and mixed-state data with magnetic fields perpendicular (H perpendicular to c) to and parallel (H parallel to c) to the c axis of the crystal and using the two-gap model, we conclude that (1) more than one energy scale of the order parameter is required for superconducting NbSe(2) due to the thermodynamic consistency; (2) Delta(L)=1.26 meV and Delta(S)=0.73 meV are obtained; (3) N(S)(0)/N(0)=11%-20%; (4) the observation of the kink in gamma(H) curve suggests that the two-gap scenario is more favorable than the anisotropic s-wave model to describe the gap structure of NbSe(2); and (5) Delta(S) is more isotropic and has a three-dimensional-like feature and is located either on the Se or the bonding Nb Fermi sheets.
Experimental evidence for a two-gap structure of superconducting NbSe2: A specific-heat study in external magnetic fields
(2007-12-01)
Huang, C. L.
;
Lin, J. -Y.
;
Chang, Y. T.
;
Sun, C. P.
;
Shen, H. Y.
To resolve the discrepancies of the superconducting order parameter in quasi-two-dimensional NbSe2, comprehensive specific-heat measurements have been carried out. By analyzing both the zero-field and mixed-state data with magnetic fields perpendicular (H perpendicular to c) to and parallel (H parallel to c) to the c axis of the crystal and using the two-gap model, we conclude that (1) more than one energy scale of the order parameter is required for superconducting NbSe2 due to the thermodynamic consistency; (2) Delta(L)=1.26 meV and Delta(S)=0.73 meV are obtained; (3) N-S(0)/N(0)=11%-20%; (4) the observation of the kink in gamma(H) curve suggests that the two-gap scenario is more favorable than the anisotropic s-wave model to describe the gap structure of NbSe2; and (5) Delta(S) is more isotropic and has a three-dimensional-like feature and is located either on the Se or the bonding Nb Fermi sheets.
High-efficiency Q-switched dual-wavelength emission at 1176 and 559 nm with intracavity Raman and sum-frequency generation
(2009-07-06)
Chang, Y. T.
;
Chang, H. L.
;
Su, K. W.
;
Chen, Y. F.
;
電子物理學系
An efficient Q-switched dual-wavelength laser with self-frequency Raman conversion in composite Nd:YVO(4) and intracavity sum-frequency generation in BBO is reported. With an input pump power of 17.5 W, average power of 0.53 W at the first-Stokes 1176 nm and average power of 1.67 W at the sum-frequency mixed 559 nm are simultaneously generated at a pulse repetition rate of 100 kHz, corresponding to a total conversion efficiency of 12.5%. (C) 2009 Optical Society of America
High-peak-power diode-pumped actively Q-switched Nd : YAG intracavity Raman laser with an undoped YVO4 crystal - art. no. 68712J
(2008)
Su, K. W.
;
Chang, Y. T.
;
Chen, Y. F.
;
電子物理學系
;
Department of Electrophysics
The efficient stimulated Raman scattering conversion in a diode-pumped actively Q-switched Nd:YAG laser was achieved with an undoped YVO4 crystal as a Raman shifter. With an incident pump power of 16.2 W, 1176-nm first Stokes average output power of 2.97 W was generated at a pulse repetition rate of 50 kHz. The maximum pulse energy is higher than 83 mu J at both 20 kHz and 30 kHz. With mode-locked modulation, the effective pulse width far above threshold is usually below 5 ns. With an incident pump power of 7.62 W, the peak-power of 43.5 kW was demonstrated at 20 kHz.
Power scale-up of the diode-pumped actively Q-switched Nd : YVO4 Raman laser with an undoped YVO4 crystal as a Raman shifter
(2007-06-01)
Su, K. W.
;
Chang, Y. T.
;
Chen, Y. F.
;
電子物理學系
;
Department of Electrophysics
With an undoped YVO4 crystal as a Raman shifter, we substantially improved the reliability and the output performance of an actively Q-switched 1176-nm Nd:YVO4 Raman laser. With an incident pump power of 18.7 W, the average power is greater than 2.6 W at 80 kHz. The pulse width of the pulse envelope is shorter then 5 ns with mode-locked modulation. With an incident pump power of 12.7 W, the pulse energy and peak power is higher than 43 mu J and 14 kW at 40 kHz.
Subnanosecond mJ eye-safe laser with an intracavity optical parametric oscillator in a shared resonator
(2009-02-02)
Huang, Y. P.
;
Chang, H. L.
;
Huang, Y. J.
;
Chang, Y. T.
;
Su, K. W.
We theoretically verify that the threshold of an intracavity optical parametric oscillator pumped by a passively Q-switched laser is entirely controlled by the bleach of the saturable absorber not by the signal output reflectivity. We use a series of different output couplers to optimize the output performance. With a signal output reflectivity of 15%, we experimentally achieve an efficient subnanosecond eye-safe laser with 3.3 mJ pulse energy and 1.5 MW peak power. @ 2008 Optical Society of America