Browsing by Author "Cho, H. H."

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Diode-Pumped Nd:YAP Intracavity Optical Parametric Oscillator Emitting at 1603 nm: Influence of Energy-Transfer Upconversion
(2016-06-01)
Cho, H. H.
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Huang, Y. J.
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Chen, W. D.
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Zhang, G.
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Chen, Y. F.
A diode-end-pumped actively Q-switched Nd:YAP laser at 1080 nm is originally designed to intracavity pump a Potassium Titanyl Phosphate KTiOPO4 (KTP)-based optical parametric oscillator for obtaining the signal wavelength at 1603 nm. Under an absorbed pump power value of 11 W, the maximum average output power at the eye-safe radiation is efficiently generated to be 1.11 W at a pulse repetition rate of 10 kHz. At a pulse repetition rate of 5 kHz, the shortest pulse duration, the largest pulse energy, and the highest peak power are found to be 2.4 ns, 190 mu J, and 67.3 kW, respectively. In addition, the influence of energy-transfer upconversion effect on the capability of power scaling of the developed Nd: YAP fundamental laser is experimentally investigated and theoretically analyzed.
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.
Dual-Wavelength Intracavity OPO With a Diffusion-Bonded Nd: YVO4/Nd:GdVO4 Crystal
(2016-05-15)
Huang, Y. J.
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Cho, H. H.
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Su, K. W.
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Chen, Y. F.
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電子物理學系
A novel diffusion-bonded Nd: YVO4/Nd: GdVO4 crystal is originally designed for developing a high-power diode-end-pumped actively Q-switched laser emitting synchronous pulses at 1063.17 and 1064.41 nm. The maximum total average output power of 6.4 W is efficiently generated under an incident pump power of 21.6 W, whereas the shortest pulse duration, largest pulse energy, and highest peak power are achieved to be 9 ns, 285 mu J, and 31.7 kW, respectively. By constructing an intracavity optical parametric oscillator with a monolithic cavity, the emission wavelengths are further extended to the eye-safe region with the maximum total average output power of 2.3 W at 1570.36 and 1572.55 nm, corresponding to the optical conversion efficiency of up to 10.6%.
Effect of spatial hole burning on a dual-wavelength mode-locked laser based on compactly combined dual gain media
(2014-12-01)
Huang, Y. J.
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Tzeng, Y. S.
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Cho, H. H.
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Chen, Y. F.
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電子物理學系
The effect of spatial hole burning (SHB) on dual-wavelength self-mode-locked lasers based on physically combined Nd:YVO4/Nd:LuVO4 and Nd:YVO4/Nd:KGW composite active medium is comparatively investigated. The length of the first Nd:YVO4 crystal is optimized to realize a highly compact and efficient TEM00-mode pico-second laser at 1.06 mu m with optical conversion efficiency greater than 20%. When the SHB effect is enhanced by decreasing the separation between the input end mirror and the composite gain medium, it is experimentally found that not only the pulse duration monotonically decreases, but also the temporal behavior gradually displays a narrow-peak-on-a-pedestal shape for the Nd:YVO4/Nd:LuVO4 scheme, while the multipulse operation can be obtained for the Nd:YVO4/Nd: KGW configuration. These phenomena are further explored by numerically simulating mode-locked pulses from the experimentally measured optical spectra. (C) 2014 Chinese Laser Press
Efficient dual-wavelength diode-end-pumped laser with a diffusion-bonded Nd:YVO4/Nd:GdVO4 crystal
(2015-10-01)
Huang, Y. J.
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Cho, H. H.
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Tzeng, Y. S.
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Liang, H. C.
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Su, K. W.
A new type of diffusion-bonded Nd:YVO4/Nd:GdVO4 hetero-composite crystal is originally designed and applied to diode-end-pumped laser for achieving an efficient dual-comb picosecond operation with self-mode locking for the first time. As high as 1.1 W of the total average output power at 1063.18 and 1064.37 nm is generated under an incident pump power of 5.1 W. The corresponding mode-locked pulse width is 42 ps at a pulse repetition rate of 3.82 GHz. Through the optical beating between two carrier frequencies of each spectral component, a train of ultrashort pulses with sub-terahertz repetition rate is further generated with the effective duration of down to 1.6 ps. (C) 2015 Optical Society of America.
Generation of multiple spectral bands in a diode-pumped self-mode-locked Nd:YAP laser
(2016-02)
Huang, Y. J.
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Tzeng, Y. S.
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Cho, H. H.
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Chen, Y. F.
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Chen, W. D.
A single- and multispectral-band diode end-pumped self-mode-locked Nd:YAP laser is originally demonstrated with an intracavity etalon to properly control the gain-to-loss ratios among the intermanifold lines on the F-4(3/2) -> I-4(11/2) transition level. With a pulse repetition rate of 5.07 (3Hz, the shortest pulse durations under the single-spectral-hand operation are achieved to be 11.1 ps at 1073 nm, 10.9 ps at 1080 nm, and 15.1 ps at 1084 nm, respectively. Moreover, the temporal overlapping of the multispectral-band pulses is experimentally found to lead to the generation of an intensity fringe pattern in the autocorrelation trace with the optical-beat frequency reaching several terahertz. A simple mathematical model is developed to elucidate the formation of a train of optical-beat pulses.
Theoretical and experimental studies for high-repetition-rate disordered crystal lasers with harmonic self-mode locking
(2016-02-22)
Sung, C. L.
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Lee, C. Y.
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Cho, H. H.
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Huang, Y. J.
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Chen, Y. F.
A harmonically self-mode-locked Nd:Sr3Y2(BO3)(4) disordered crystal laser with subpicosecond pulse duration is demonstrated. We exploit the damped harmonic oscillator model to numerically verify that the mode spacing of the laser cavity can be modified to be the harmonics of the free spectral range of the Fabry-Perot cavity when the optical length of the laser cavity is close to a commensurate ratio of the optical length of the FabryPerot cavity. In experiment, the Fabry-Perot cavity can be formed by the pump facet of the disordered crystal and the front mirror. A 110 GHz single-pulse harmonically mode-locked pulse train with pulse duration of 857 fs is experimentally achieved under optical lengths of 27.19 and 4.08 mm for the laser cavity and Fabry-Perot cavity respectively, corresponding to a fractional number of 20/3. A maximum output power of 162 mW is obtained at an incident pump power of 3.1 W. (C)2016 Optical Society of America