Browsing by Author "Cho, Chun-Yu"

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Achieving dual-wavelength co-linear emission at quasi-three-level and four-level transitions with compactly combined dual gain media
(2016)
Cho, Chun-Yu
;
Chen, Yung-Fu
;
電子物理學系
;
Department of Electrophysics
A dual-wavelength laser at four-level and quasi-three-level transitions is demonstrated in a linear resonator. The compactly combined Nd:YAG and Nd:YVO4 crystals successfully improve the efficiency limitation for the dilemma between reabsorption loss and absorption reduction.
Comparative Study Between Extracavity and Intracavity Frequency-Doubled Laser at 532 nm: Application for the Deep Ultraviolet Generation at 266 nm
(2015-01-01)
Huang, Yu-Jen
;
Tang, Cheng-Yu
;
Cho, Chun-Yu
;
Su, Kuan-Wei
;
Chen, Yung-Fu
We construct a reliable actively Q-switched Nd:YVO4 laser to comparatively investigate the output performance of the second harmonic generation between the extracavity and intracavity configurations under a similar operated condition. It is experimentally found that the peak power at 532 nm obtained with the extracavity second harmonic generation is remarkably higher than that obtained with the intracavity configuration, even though the higher output power and larger pulse energy can be acquired with the intracavity second harmonic generation. We further perform the extracavity fourth harmonic generation to verify that the extracavity second harmonic generation is more advantageous in generating deep ultraviolet laser at 266 nm than the intracavity one, where the conversion efficiencies from 532 to 266 nm for each case are 37.1% and 7.2%, respectively. Moreover, under an incident pump power of 26 W at 808 nm and a pulse repetition rate of 40 kHz, the output power at 266 nm as high as 1.67 W is effectually generated with the combination of the extracavity second and fourth harmonic generations, corresponding to the conversion efficiency from 808 to 266 nm up to 6.4%.
Cryogenic monolithic Nd: YAG laser at 946 nm with > 70% slope efficiency
(2016)
Cho, Chun-Yu
;
Chen, Yung-Fu
;
電子物理學系
;
Department of Electrophysics
An efficient cryogenic quasi-three-level Nd: YAG laser is demonstrated by employing a monolithic resonator. The output performance for the laser at cryogenic temperature is theoretically analyzed to be consistent with experimental results.
Exploring the power scaling of the cryogenic 946 nm monolithic laser
(2018-08-01)
Cho, Chun-Yu
;
Huang, Tzu-Lin
;
Cheng, Hao-Ping
;
Huang, Kai-Feng
;
Chen, Yung-Fu
The criterion for achieving power scaling of the cryogenically cooled monolithic 946 nm laser is investigated by varying crystal length. Theoretical analysis of the mode-to-pump size matching indicates that the optimal power can be obtained with a crystal length of 8 mm. Furthermore, the pump-wavelength dependence of the output power can be less sensitive when a longer crystal was employed. We demonstrate 946 nm monolithic lasers with various crystal lengths to verify the theoretical analysis. The highest output power (30.2 W) is obtained by using an 8 mm Nd:YAG crystal at 130 K. Moreover, the output power reduction ratio is found to be smaller than 15% with the pump wavelength fluctuating between +/- 1 nm.
Generation of Higher Order Vortex Beams From a YVO4/Nd:YVO4 Self-Raman Laser via Off-Axis Pumping With Mode Converter
(2015-01-01)
Lee, Cheng-Yeh
;
Chang, Chuan-Ching
;
Cho, Chun-Yu
;
Tuan, Pi-Hui
;
Chen, Yung-Fu
The generation of high-order Hermite-Gaussian (HG) beams at the Stokes wavelength in a YVO4/Nd:YVO4 self-Raman laser with off-axis pumping is demonstrated. The high-order vortex beams at the Stokes field are successfully created by transforming these HG modes via an extra-cavity mode converter. The stimulated Raman scattering (SRS) threshold pump power for the diode-end-pumped laser is theoretically analyzed to verify the feasibility of generating high-order HG modes by off-axis pumping. At a pump power of 18.6 W, the SRS output powers can be higher than 1.0 W for the HG modes from TEM0,0 to TEM3,0. Under the same pump power, the maximum order can be up to TEM28,0.