Browsing by Author "Chang, F. L."

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Dual-central-wavelength passively mode-locked diffusion-bonded Nd:YVO4/Nd:GdVO4 laser with a semiconductor saturable absorber mirror
(2017-08-01)
Chang, F. L.
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Sung, C. L.
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Huang, T. L.
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Wu, T. W.
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Cho, H. H.
A dual-central-wavelength passively mode-locked laser with full modulation in the 0.31 THz optical beating is achieved by using a diffusion-bonded Nd:YVO4/Nd:GdVO4 crystal and a semiconductor saturable absorber mirror. The output power of the dual-band emission is well balanced by tuning the focal position of the pump waist. At a pump power of 13 W, the total output power is up to 2.7 W with a repetition rate of 297.9 MHz. The autocorrelation traces clearly reveal the synchronization of the dual-band emission. Moreover, an analytical model is developed to manifest the multi-pulse structure caused by the etalon effect of the gain medium. More important, we experimentally verify that the etalon effect can be completely eliminated by using the wedge-cut diffusion-bonded Nd:YVO4/Nd:GdVO4 crystal.
Modelling end-pumped passively Q-switched Nd-doped crystal lasers: manifestation by a Nd:YVO4/Cr4+:YAG system with a concave-convex resonator
(2017-02-06)
Tuan, P. H.
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Chang, C. C.
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Chang, F. L.
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Lee, C. Y.
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Sung, C. L.
A theoretical model for the passively Q-switched (PQS) operation which includes the spatial overlapping between the pump and lasing modes under the thermal lensing effect is developed to give a transcendental equation that can directly determine the critical parameters such as pulse energy, pulse repetition rate, and pulse width for the PQS performance. More importantly, an analytical function which gives the approximate solution for the transcendental equation as well as a specific critical criterion for good PQS operation are derived for practical analyses and design. A Nd: YVO4/Cr4+: YAG system with a concave-convex resonator which can achieve fairly stable PQS pulse trains even at a high pump level is further exploited to manifest the proposed spatially dependent model. The good agreement between the experimental results and the theoretical predictions is verified to show the feasibility of the proposed model for designing high-power PQS lasers with high accuracy. (C) 2017 Optical Society of America
Selective pumping and spatial hole burning for generation of photon wave packets with ray-wave duality in solid-state lasers
(2016-02)
Tung, J. C.
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Liang, H. C.
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Tuan, P. H.
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Chang, F. L.
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Huang, K. F.
The selective pumping and the spatial hole burning are thoroughly considered to determine the excited transverse and longitudinal eigenmodes. By using the mode locking of the excited eigenmodes, an analytical wave representation is derived to manifest the ray-wave duality of the optical wave packet dynamics in the laser resonator. The derived wave function is employed to extract the parametric formula for the periodic ray orbits that reveal the subtle origin between the hyperbolic caustics and linear trajectories. Moreover, the temporal dynamics of the output beam for the total mode-locked state is theoretically demonstrated by combining with the parametric formula and the derived wave function. More importantly, an experiment based on the self-mode-locked laser is performed to make a comparison with theoretical analysis.