Browsing by Author "Huang, K. F."

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24-W cryogenically cooled Nd:YAG monolithic 946-nm laser with a slope efficiency > 70%
(2015-04-20)
Cho, C. Y.
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Lee, C. Y.
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Chang, C. C.
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Tuan, P. H.
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Huang, K. F.
A high-power efficient monolithic Nd: YAG 946-nm laser is demonstrated at the cryogenic temperature. By exploring the absorption and the fluorescence spectra of the Nd: YAG crystal, it reveals the fact that the absorption bandwidth at 808 nm is narrowing and the fluorescence intensity at 1061 nm is significant enhanced when the temperature is decreased. The temperature dependence of the lasing threshold at 946 nm is found to display a minimum value near a temperature of 170 K. At an incident pump power of 34.5 W, the local heating leads the optimum temperature to be approximately 120 K and the maximum output power can reach 24.4 W with the conversion efficiency of 71% as well as the slope efficiency up to 75%. (C)2015 Optical Society of America
A cryogenically cooled Nd:YAG monolithic laser for efficient dual-wavelength operation at 1061 and 1064 nm
(2013-04-01)
Cho, C. Y.
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Tuan, P. H.
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Yu, Y. T.
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Huang, K. F.
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Chen, Y. F.
We experimentally explore the fluorescence spectra of the Nd:YAG (YAG: yttrium aluminum garnet) crystal at cryogenic temperatures to confirm the feasibility of dual-wavelength operation at 1061 and 1064 nm. Furthermore, a cryogenically cooled Nd:YAG crystal with coating to form a monolithic cavity is employed to investigate the performance of the dual-wavelength operation. At an incident pump power of 20 W, the output powers for each wavelength can simultaneously reach 6.0 W at the optimally balanced temperature of 152 K. The optimal temperature for balancing the output powers of the two wavelengths is experimentally determined as a function of the incident pump power intensity.
AlGaInAs intracavity selective absorber for an efficient high-power Nd : YAG laser operation at 1.44 mu m
(2008-07-01)
Huang, Y. P.
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Chang, Y. T.
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Su, K. W.
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Chen, Y. F.
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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.
AlGaInAs multiple-quantum-well 1.2-mu m semiconductor laser in-well pumped by an Yb-doped pulsed fiber amplifier
(2012-01-01)
Chen, Y. -F.
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Lee, Y. C.
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Huang, S. C.
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Huang, K. F.
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Chen, Y. F.
An AlGaInAs multiple quantum well structure is reported as an effective gain medium of the in-well pumped high-peak-power semiconductor disk laser at 1.2 mu m. We use an Yb-doped pulsed fiber amplifier as the pump source to effectively optimize the output characteristics. The maximum average output power of 1.28 W and peak output power of 0.76 kW is obtained at 1225 nm lasing wavelength under 60 kHz pump repetition rate and 28 ns pump pulse width.
AlGaInAs quantum-well as a saturable absorber in a diode-pumped passively Q-switched solid-state laser
(2007-06-01)
Huang, S. C.
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Liu, S. C.
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Li, A.
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Su, K. W.
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Chen, Y. F.
We demonstrate what is believed to be the first use of AlGaInAs quantum wells (QWs) as a saturable absorber in the Q switching of a high-power diode-pumped Nd-doped 1.06 mu m laser. The barrier layers are designed to locate the QW groups in the region of the nodes of the lasing standing wave to avoid damage. With an incident pump power of 13.5 W, an average output power of 3.5 W with a Q-switched pulse width of 0.9 ns at a pulse repetition rate of 110 kHz was obtained. (c) 2007 Optical Society of America.
AlGaInAs/InP eye-safe laser pumped by a Q-switched Nd:GdVO(4) laser
(2009-03-01)
Huang, S. C.
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Chang, H. L.
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Su, K. W.
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Li, A.
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Liu, S. C.
An AlGaInAs quantum-well structure grown on a Fe-doped InP transparent substrate is developed to be a gain medium in a high-peak-power nanosecond laser at 1570 nm. Using an actively Q-witched 1064 nm laser to pump the gain chip, an average output power of 135 mW is generated at a pulse repetition rate of 30 kHz and an average pump power of 1.25 W. At a pulse repetition rate of 20 kHz, the peak output power is up to 290 W at a peak pump power of 2.3 kW.
AlGaInAs/InP eye-safe laser pumped by a Q-switched Nd:GdVO4 laser
(2009-03-01)
Huang, S. C.
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Chang, H. L.
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Su, K. W.
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Li, A.
;
Liu, S. C.
An AlGaInAs quantum-well structure grown on a Fe-doped InP transparent substrate is developed to be a gain medium in a high-peak-power nanosecond laser at 1570 nm. Using an actively Q-witched 1064 nm laser to pump the gain chip, an average output power of 135 mW is generated at a pulse repetition rate of 30 kHz and an average pump power of 1.25 W. At a pulse repetition rate of 20 kHz, the peak output power is up to 290 W at a peak pump power of 2.3 kW.
Analysis of polarization states of broad-area vertical-cavity surface-emitting lasers below and above threshold
(2009)
Schulz-Ruhtenberg, M.
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Babushkin, I. V.
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Loiko, N. A.
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Huang, K. F.
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Ackemann, T.
The polarization direction of broad-area vertical-cavity surface-emitting lasers is found to be parallel to the wavevector below threshold. The characteristics of the transition through threshold are studied.
Analysis of the optimal temperature for the cryogenic monolithic Nd:YAG laser at 946-nm
(2016-01-11)
Cho, C. Y.
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Huang, T. L.
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Cheng, H. P.
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Huang, K. F.
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Chen, Y. F.
The optimal temperature for the cryogenic monolithic Nd:YAG laser at 946-nm is theoretically and experimentally analyzed. It is clear that decreasing temperature can considerably eliminate the thermal population at the lower laser level to enhance the quantum efficiency. However, the narrowing of the absorption bandwidth for the gain medium leads to a reduction of the effective absorption efficiency as the temperature is decreased. Consequently, an optimal temperature for the maximum output power is found to be in the range of approximately 120 K to 140 K. It is experimentally verified that employing a pump source with a narrower emission spectrum linewidth contributes a more efficient output for the cryogenic laser. (C) 2016 Optical Society of America
Astigmatism inducing the degenerate effect in nearly hemispherical cavities: Generation of three-dimensional structured light
(2017-01-01)
Tung, J. C.
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Hsieh, Y. H.
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Liang, H. C.
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Su, K. W.
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Huang, K. F.
We originally perform an analytical form to explore the influence of the astigmatism on the degenerate effect in nearly hemispherical cavities. The frequency spectrum near hemispherical cavities clearly reveals that not only the difference of cavity lengths between each degeneracies but also frequency gaps have significant difference from non-hemispherical cavities. We further thoroughly demonstrate the laser experiment under the condition of nearly hemispherical cavities to confirm the theoretical exploration that the transverse topology of three-dimensional (3D) structured light in the degenerate cavities is well localized on the Lissajous curves.
Characterization and generation of high-power multi-axis vortex beams by using off-axis pumped degenerate cavities with external astigmatic mode converter
(2018-08-06)
Tuan, P. H.
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Hsieh, Y. H.
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Lai, Y. H.
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Huang, K. F.
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Chen, Y. F.
The generalized geometric mode with several high-order Hermite-Gaussian (HG) beams localized on ray periodic orbits in the degenerate resonator is generated by an off-axis pumped Nd: YVO4 laser, by performing beam transformation via an astigmatic mode converter, the generalized geometric modes are found that can be converted into the multi-axis vortex beams with the bundled-rings structures. Experimental results reveal that the generated multi-axis vortex beams can preserve quite stable beam structures even under high-power operation. Moreover, the radius of the bundled rings for the multi-axis vortex beams can be flexibly adjusted by the off-axis pumping to lead to vortex structures with easily controlled orbital angular momentum distribution. The good agreement between the experimental and theoretical results of propagation evolution for the astigmatic transformation of generalized geometric modes further verify the feasibility of using the proposed system to realize various high-powered, multi-center vortex beams with good reliability and predictability. (c) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Characterizing classical periodic orbits from quantum Green's functions in two-dimensional integrable systems: Harmonic oscillators and quantum billiards
(2017-01-30)
Chen, Y. F.
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Tung, J. C.
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Tuan, P. H.
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Yu, Y. T.
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Liang, H. C.
A general method is developed to characterize the family of classical periodic orbits from the quantum Green's function for the two-dimensional (2D) integrable systems. A decomposing formula related to the beta function is derived to link the quantum Green's function with the individual classical periodic orbits. The practicality of the developed formula is demonstrated by numerically analyzing the 2D commensurate harmonic oscillators and integrable quantum billiards. Numerical analyses reveal that the emergence of the classical features in quantum Green's functions principally comes from the superposition of the degenerate states for 2D harmonic oscillators. On the other hand, the damping factor in quantum Green's functions plays a critical role to display the classical features in mesoscopic regime for integrable quantum billiards, where the physical function of the damping factor is to lead to the coherent superposition of the nearly degenerate eigenstates.
Characterizing the propagation evolution of wave patterns and vortex structures in astigmatic transformations of Hermite-Gaussian beams
(2018-01-01)
Chen, Y. F.
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Chang, C. C.
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Lee, C. Y.
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Tung, J. C.
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Liang, H. C.
Theoretical wave functions are analytically derived to characterize the propagation evolution of the Hermite-Gaussian (HG) beams transformed by a single-lens astigmatic mode converter with arbitrary angle. The derived wave functions are related to the combination of the rotation transform and the antisymmetric fractional Fourier transform. The derived formula is systematically validated by using an off-axis diode-pumped solid-state laser to generate various high-order HG beams for mode conversions. In addition to validation, the creation and evolution of vortex structures in the transformed HG beams are numerically manifested. The present theoretical analyses can be used not only to characterize the evolution of the transformed beams but to design the optical vortex beams with various forms.
Comparative studies for Cr(4+):YAG crystal and AlGaInAs semiconductor used as a saturable absorber in Q-switched Yb-doped fiber lasers
(2009-11-09)
Huang, J. Y.
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Zhuang, W. Z.
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Huang, W. C.
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Su, K. W.
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Hu, C.
We demonstrate comparative studies for Cr(4+):YAG crystal and AlGaInAs quantum-well (QW) used as a saturable absorbers in passively Q-switched Yb-doped fiber lasers. Both saturable absorbers were designed to be possessed of nearly the same initial transmission. Under a pump power of 24 W, the average output powers were up to 14.4 W and 13.8 W obtained with the AlGaInAs QWs and with the Cr(4+):YAG crystal, respectively. The maximum pulse energies obtained with the Cr(4+):YAG crystal and with the AlGaInAs QWs were found to be 0.35 mJ and 0.45 mJ, respectively. (C) 2009 Optical Society of America
Comparative studies for Cr4+:YAG crystal and AlGaInAs semiconductor used as a saturable absorber in Q-switched Yb-doped fiber lasers
(2009-11-09)
Huang, J. Y.
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Zhuang, W. Z.
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Huang, W. C.
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Su, K. W.
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Hu, C.
We demonstrate comparative studies for Cr4+:YAG crystal and AlGaInAs quantum-well (QW) used as a saturable absorbers in passively Q-switched Yb-doped fiber lasers. Both saturable absorbers were designed to be possessed of nearly the same initial transmission. Under a pump power of 24 W, the average output powers were up to 14.4 W and 13.8 W obtained with the AlGaInAs QWs and with the Cr4+:YAG crystal, respectively. The maximum pulse energies obtained with the Cr4+:YAG crystal and with the AlGaInAs QWs were found to be 0.35 mJ and 0.45 mJ, respectively. (C) 2009 Optical Society of America
Comparative study between conventional and diffusion-bonded Nd-doped vanadate crystals in the passively mode-locked operation
(2010-04-26)
Huang, Y. J.
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Huang, Y. P.
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Liang, H. C.
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Su, K. W.
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Chen, Y. F.
We design a reliable linear three-element cavity to make a comparative study between the conventional and diffusion-bonded Nd:GdVO(4) crystals in the passively mode-locked operation. Experimental investigations reveal that the mode-locked pulse width obtained with the diffusion-bonded crystal is considerably broader than that obtained with the conventional crystal, even though the diffusion-bonded crystal can significantly reduce the thermal effects. The pulse broadening is experimentally verified to come from the length of the undoped part that brings in a reduction of the spatial-hole-burning (SHB) effect. (C) 2010 Optical Society of America
Control of the spatial emission structure of broad-area vertical-cavity surface-emitting lasers by feedback
(2009-03-07)
Schulz-Ruhtenberg, M.
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Tanguy, Y.
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Huang, K. F.
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Jaeger, R.
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Ackemann, T.
The wave number of transverse spatial structures in broad-area vertical-cavity surface-emitting lasers (VCSELs) is controlled via frequency-selective feedback from an external self-imaging cavity in a broad range of wave numbers and emission frequencies. The selected states follow the dispersion curves of the free-running laser. A control range of about 2.5 mu m(-1) in spatial frequency space and 2.5 nm in emission wavelength was obtained for square VCSELs and of about 3 mu m(-1) and 8 nm for circular VCSELs having a different dispersion curve. By spatial filtering in Fourier space, the shape of the structures can also be controlled to some extent. It is argued that the feedback techniques are useful to 'probe' emission states of the free-running laser.
Coupling of polarization and spatial degrees of freedom of highly divergent emission in broad-area square vertical-cavity surface-emitting lasers
(2008-05-30)
Babushkin, I. V.
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Schulz-Ruhtenberg, M.
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Loiko, N. A.
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Huang, K. F.
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Ackemann, T.
The polarization of highly divergent modes of broad-area square vertical-cavity surface-emitting lasers is shown to be only marginally affected by material anisotropies but determined by an interplay of the polarization properties of the Bragg cavity mirrors and of the transverse boundary conditions. This leads to a locking of the polarization direction to the boundaries and its indeterminacy for wave vectors oriented along the diagonal. We point out a non-Poissonian character of nearest-neighbor frequency spacing distribution and the impossibility of single-wave number solutions.
Cryogenically monolithic self-Raman lasers: observation of single-longitudinal-mode operation
(2015-05-01)
Lee, C. Y.
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Chang, C. C.
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Tuan, P. H.
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Cho, C. Y.
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Huang, K. F.
A cryogenically monolithic Nd:YVO4 self-Raman laser is experimentally explored and theoretically analyzed. The variation of the stimulated Raman scattering (SRS) threshold on the temperature is found to be nonlinear because the reduction of thermal lensing enlarges the cavity mode size. In spite of the nonlinear variation of the SRS threshold on the temperature, the overall SRS output power can be efficiently increased from 0.78 to 1.36 W for temperature decreasing from 285 to 80 K at an absorbed power of 17.2 W. More interestingly, the single-longitudinal-mode operation is experimentally achieved when temperature is lower than 125 K. (C) 2015 Optical Society of America
Diode-pumped passively mode-locked 1342 nm Nd:YVO(4) laser with an AlGaInAs quantum-well saturable absorber
(2009-08-01)
Huang, S. C.
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Cheng, H. L.
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Chen, Yi-Fan
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Su, K. W.
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Chen, Y. F.
We demonstrate what we believe to be the first use of AlGaInAs quantum wells (QWs) as a saturable absorber for a diode-pumped passively mode locked Nd:YVO(4) laser at 1342 nm. The QWs are grown on a Fedoped InP substrate that is transparent at lasing wavelength. At an incident pump power of 13.5 W an average output power of 1.05 W with a continuous mode-locked pulse duration of 26.4 ps at a repetition rate of 152 MHz was generated. (C) 2009 Optical Society of America