Browsing by Author "Chang, LB"

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Efficient all-solid-state deep ultraviolet laser source
(2001)
Chang, LB
;
Wang, SC
;
Kung, AH
;
光電工程學系
;
Department of Photonics
Stable watt level operation in the UV is achieved from a laser-diode-pumped Nd:YAG laser by fourth-harmonic generation in an external cavity. Over 1.4 watt at 266 nm in a TEMoo beam was obtained, and long term stability better than 99% (>1 hr) . 284mW at 213 nm were also obtained from 830 mW at 266 nm.
Efficient compact watt-level deep-ultraviolet laser generated from a multi-kHz Q-switched diode-pumped solid-state laser system
(2002-08-15)
Chang, LB
;
Wang, SC
;
Kung, AH
;
光電工程學系
;
Department of Photonics
Stable high-power operation in the deep ultraviolet is achieved from a multi-kHz diode-pumped multi-longitudinal-mode Q-switched Nd:YAG laser by fourth harmonic generation in an external resonant cavity and by fifth harmonic generation using sum-frequency mixing of the fourth harmonic and the residual fundamental in a beta-BBO crystal. Over 2.1 W of 266 nm radiation and 540 mW of 213 nm radiation were generated from a fundamental power of 7 W of 1064 nm light at 5 kHz. The overall conversion efficiency from IR to deep ultraviolet at 213 nm is larger than 7.5%. (C) 2002 Elsevier Science B.V. All rights reserved.
High-sensitivity sensor based on surface plasmon resonance and heterodyne interferometry
(2003-07-01)
Wu, CM
;
Jian, ZC
;
Joe, SF
;
Chang, LB
;
交大名義發表
A common-path, heterodyne interferometric system for investigation of the phase variations under surface plasmon resonance (SPR) is presented. With the combination of SPR and total internal reflection (TIR), the system has the merits of avoiding direction change in the output light and increasing sensitivity. The system utilizes a pair of orthogonally linearly polarized beams with heterodyne frequency of 60 kHz as the light source. Because the two beams are perfectly collinear, the noises resulting from the ambient conditions are greatly reduced. Compared to reflectivity variation measurement, which is widely used in traditional SPR, the phase variation measurement using commonpath, heterodyne techniques is approximately an order of magnitude higher in sensitivity and thus can be used as a high-sensitivity-demanded biosensor. (C) 2003 Elsevier Science B.V. All rights reserved.
Numerical analysis of fifth-harmonic conversion of low-power pulsed Nd : YAG laser with resonance of second harmonic
(2003-07-01)
Chang, LB
;
Wang, SC
;
Kung, AH
;
光電工程學系
;
Department of Photonics
A model for the fifth-harmonic generation of pulsed IR lasers involving an external ring cavity resonating at the second harmonic has been developed. Numerical analysis is performed to show the relative effects of the pulse delay, input polarization, and orientation of the nonlinear crystals on the fifth harmonic power. The results are validated by published experimental results. The model is used to analyze and obtain the optimal combination of nonlinear optical crystals for the fifth-harmonic generation. Our calculation shows that the combination of LiB3O5 (LBO), CsLiB6O10 (CLBO), and CLBO crystals for the second-harmonic, fourth-harmonic, and fifth-harmonic generation steps respectively gives an approximate conversion of 30% from the fundamental to the fifth harmonic power, resulting in 2W at 213 nm for an input of 7W at 1064nm.
Numerical study of multiple-pass effect by total internal reflection on second-harmonic conversion in KBe2BO3F2 crystal
(2004-02-01)
Chang, LB
;
Wang, SC
;
光電工程學系
;
Department of Photonics
We apply total internal reflection to significantly extend the effective length of KBe2BO3F2 crystal. Thus the conversion efficiency for second-harmonic generation can be increased in principle. However, the total reflection also leads to an adverse effect on the conversion efficiency. Three multiple-pass configurations to extend the effective interaction length of the crystal are proposed and discussed in this paper. Numerical analysis shows that the double-pass configuration is more favorable for second-harmonic generation to below 200 nm. At the medium input intensity of 200 MW/cm(2), the configuration gives a conversion of 27.1% at the second-harmonic wavelength of 193 nm. A conversion of 45.2% is obtained as the input intensity is increased to a higher value of 500 MW/cm(2).