Browsing by Author "Chiang, P. Y."

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Controlling number of lasing modes for designing short-cavity self-mode-locked Nd-doped vanadate lasers
(2011-06-01)
Chen, Y. F.
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Huang, Y. J.
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Chiang, P. Y.
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Lin, Y. C.
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Liang, H. C.
A short-cavity Nd:YVO(4) laser is employed to confirm that a spontaneous mode locking (SML) typically occurs without employing an extra nonlinearity. We further experimentally demonstrate that reducing the number of longitudinal lasing modes can diminish the phase fluctuation and effectively improve the SML pulse stability. Considering the spatial hole-burning (SHB) effect, an analytical expression is derived to accurately estimate the number of longitudinal lasing modes for a practical design guideline.
Efficient high-power UV laser generated by an optimized flat-flat actively Q-switched laser with extra-cavity harmonic generations
(2012-01-01)
Huang, Y. J.
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Chiang, P. Y.
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Liang, H. C.
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Su, K. W.
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Chen, Y. F.
We investigate the parasitic lasing effect in the high-power actively Q-switched laser with a flat-flat resonator. The parasitic lasing effect in the low-Q stage is found to lead to long tails in the output pulses, corresponding to the peak-power reduction. We experimentally determine the shortest cavity length without the parasitic lasing effect to optimize the performance of the high-power actively Q-switched laser with a flat-flat cavity. We further use the optimized fundamental laser to generate green and UV lasers by extra-cavity harmonic generations. At a pump power of 44 W, the output powers at 355 nm and 532 nm as high as 6.65 W and 8.38 W are obtained at a pulse repetition rate of 40 kHz. (C) 2011 Elsevier B.V. All rights reserved.
Exploring the effect of fractional degeneracy and the emergence of ray-wave duality in solid-state lasers with off-axis pumping
(2013-07-18)
Chen, Y. F.
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Tung, J. C.
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Chiang, P. Y.
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Liang, H. C.
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Huang, K. F.
We employ the inhomogeneous Helmholtz equation to explore the influence of the fractional degeneracy and the pump distribution on the resonant lasing mode. Theoretical analyses clearly reveal the relationship between the fractional degeneracy and the emergence of the ray-wave duality. Furthermore, we perform thorough laser experiments to confirm the theoretical exploration that the resonant modes near the degenerate cavities are well localized on the ray trajectories under the condition of the off-axis pumping. We also exploit the derived wave functions to calculate the resonant strengths that can noticeably manifest the enhancements of the output powers in the degenerate cavities.
Exploring the resonant vibration of thin plates: Reconstruction of Chladni patterns and determination of resonant wave numbers
(2015-04-01)
Tuan, P. H.
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Wen, C. P.
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Chiang, P. Y.
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Yu, Y. T.
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Liang, H. C.
The Chladni nodal line patterns and resonant frequencies for a thin plate excited by an electronically controlled mechanical oscillator are experimentally measured. Experimental results reveal that the resonant frequencies can be fairly obtained by means of probing the variation of the effective impedance of the exciter with and without the thin plate. The influence of the extra mass from the central exciter is confirmed to be insignificant in measuring the resonant frequencies of the present system. In the theoretical aspect, the inhomogeneous Helmholtz equation is exploited to derive the response function as a function of the driving wave number for reconstructing experimental Chladni patterns. The resonant wave numbers are theoretically identified with the maximum coupling efficiency as well as the maximum entropy principle. Substituting the theoretical resonant wave numbers into the derived response function, all experimental Chladni patterns can be excellently reconstructed. More importantly, the dispersion relationship for the flexural wave of the vibrating plate can be determined with the experimental resonant frequencies and the theoretical resonant wave numbers. The determined dispersion relationship is confirmed to agree very well with the formula of the Kirchhoff-Love plate theory. (c) 2015 Acoustical Society of America.
High-power passively Q-switched Nd:YVO4 UV laser at 355 nm
(2012-03-01)
Huang, Y. J.
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Huang, Y. P.
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Chiang, P. Y.
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Liang, H. C.
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Su, K. W.
We report on an efficient high-power passively Q-switched UV laser at 355 nm. We take into account the second threshold criterion and the thermal-lensing effect to design and realize a compact reliable passively Q-switched Nd:YVO4 laser with Cr4+:YAG as a saturable absorber. At an incident pump power of 16.3W, the average output power at 1064 nm reaches 6.2 W with a pulse width of 7 ns and a pulse repetition rate of 56 kHz. Employing the developed passively Q-switched laser to perform the extra-cavity harmonic generations, the maximum average output powers at 532 nm and 355 nm are up to 2.2 W and 1.62 W, respectively.
High-power Q-switched laser with high-order Laguerre-Gaussian modes: application for extra-cavity harmonic generations
(2011-11-01)
Huang, Y. J.
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Chiang, P. Y.
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Liang, H. C.
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Su, K. W.
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Chen, Y. F.
We present a compact efficient scheme for generation of high-order Laguerre-Gaussian TEM (p,0) modes in a diode-pumped actively Q-switched Nd:YVO(4) laser. The resonator is composed of two plane mirrors with an intracavity concave lens to expand the cavity mode size for generating a high-power Laguerre-Gaussian TEM(5,0) mode. We further confirm that the TEM(5,0) mode is noticeably superior to the TEM(0,0) mode in the processes of second and third harmonic generations.
High-repetition-rate megawatt millijoule pulses from a Nd:YVO(4) laser passively Q-switched by a semiconductor saturable absorber
(2011-05-01)
Huang, Y. P.
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Chiang, P. Y.
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Huang, Y. J.
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Su, K. W.
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Chen, Y. F.
We exploit an AlGaInAs periodic quantum-well absorber with a large modulation strength to realize a multi-mJ passively Q-switched Nd:YVO(4) laser with a repetition rate up to 200 Hz. At a pump energy of 34 mJ, the output pulse energy and the peak power are found to be 3.5 mJ and 1.1 MW, respectively. The fluctuation of the output pulse energy is generally less than +/- 2%.
High-repetition-rate megawatt millijoule pulses from a Nd:YVO4 laser passively Q-switched by a semiconductor saturable absorber
(2011-05-01)
Huang, Y. P.
;
Chiang, P. Y.
;
Huang, Y. J.
;
Su, K. W.
;
Chen, Y. F.
We exploit an AlGaInAs periodic quantum-well absorber with a large modulation strength to realize a multi-mJ passively Q-switched Nd:YVO4 laser with a repetition rate up to 200 Hz. At a pump energy of 34 mJ, the output pulse energy and the peak power are found to be 3.5 mJ and 1.1 MW, respectively. The fluctuation of the output pulse energy is generally less than +/- 2%.
Highly efficient Nd:Gd(0.6)Y(0.4)VO(4) laser by direct in-band pumping at 914 nm and observation of self-mode-locked operation
(2011-06-01)
Liang, H. C.
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Huang, Y. J.
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Chiang, P. Y.
;
Chen, Y. F.
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電子物理學系
A highly efficient Nd:Gd(0.6)Y(0.4)VO(4) laser by direct in-band pumping at 914 nm is demonstrated for the first time. With an absorbed power of 3.7 W, a maximum output power of 2.65 W at 1064 nm was obtained, corresponding to an optical conversion efficiency of 72%. We also experimentally observed that the laser system could be efficiently operated in the self-mode-locked state in the range of 0.9-3.3 GHz. The pulse width was measured to be 16 ps at a repetition rate of 1.75 GHz.
Highly efficient Nd:Gd0.6Y0.4VO4 laser by direct in-band pumping at 914 nm and observation of self-mode-locked operation
(2011-06-01)
Liang, H. C.
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Huang, Y. J.
;
Chiang, P. Y.
;
Chen, Y. F.
;
電子物理學系
A highly efficient Nd:Gd0.6Y0.4VO4 laser by direct in-band pumping at 914 nm is demonstrated for the first time. With an absorbed power of 3.7 W, a maximum output power of 2.65 W at 1064 nm was obtained, corresponding to an optical conversion efficiency of 72%. We also experimentally observed that the laser system could be efficiently operated in the self-mode-locked state in the range of 0.9-3.3 GHz. The pulse width was measured to be 16 ps at a repetition rate of 1.75 GHz.
Level statistics and eigenfunctions of square torus billiards: Manifesting the transition from regular to chaotic behaviors
(2012-02-02)
Tuan, P. H.
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Yu, Y. T.
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Chiang, P. Y.
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Liang, H. C.
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Huang, K. F.
We thoroughly analyze the level statistics and eigenfunctions in concentric as well as nonconcentric square torus billiards. We confirm the characteristics of quantum and classical correspondence and the existence of scarred and superscarred modes in concentric square torus billiards. Furthermore, we not only verify that the transition from regular to chaotic behaviors can be manifested in nonconcentric square torus billiards, but also develop an analytical distribution to excellently fit the numerical level statistics. Finally, we intriguingly observe that numerous eigenstates commonly exhibit the wave patterns to be an ensemble of classical diamond trajectories, as the effective wavelengths are considerably shorter than the size of internal hole.
Manifestation of quantum-billiard eigenvalue statistics from subthreshold emission of vertical-cavity surface-emitting lasers
(2011-01-11)
Chen, Y. F.
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Yu, Y. T.
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Chiang, P. Y.
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Tuan, P. H.
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Huang, Y. J.
We report that the subthreshold emission spectra of vertical-cavity surface-emitting lasers (VCSELs) can be analogously used to manifest the quantum-billiard energy spectra. The Fourier-transformed distributions of the subthreshold emission spectra are demonstrated to display various peak structures that are in good agreement with the results of the quantum-billiard model. We also verify that the statistical analyses of the nearest-neighbor eigenvalue spacing distributions obey a Poisson distribution for an equilateral-triangular device and a Wigner distribution for a stadium-shaped device.
Manifesting the evolution of eigenstates from quantum billiards to singular billiards in the strongly coupled limit with a truncated basis by using RLC networks
(2015-12-07)
Tuan, P. H.
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Liang, H. C.
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Tung, J. C.
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Chiang, P. Y.
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Huang, K. F.
The coupling interaction between the driving source and the RLC network is explored and characterized as the effective impedance. The mathematical form of the derived effective impedance is verified to be identical to the meromorphic function of the singular billiards with a truncated basis. By using the derived impedance function, the resonant modes of the RLC network can be divided into the open-circuit and short-circuit states to manifest the evolution of eigenvalues and eigenstates from closed quantum billiards to the singular billiards with a truncated basis in the strongly coupled limit. The substantial differences of the wave patterns between the uncoupled and strongly coupled eigenmodes in the two-dimensional wave systems can be clearly revealed with the RLC network. Finally, the short-circuit resonant states are exploited to confirm that the experimental Chladni nodal-line patterns in the vibrating plate are the resonant modes subject to the strong coupling between the oscillation system and the driving source.
Millijoule intracavity OPO driven by a passively Q-switched Nd:YVO(4) laser with AlGaInAs quantum-well saturable absorber
(2011-09-01)
Huang, Y. P.
;
Chiang, P. Y.
;
Chen, Y. F.
;
Huang, K. F.
;
電子物理學系
We originally demonstrate the use of an AlGaInAs periodic quantum-well absorber to achieve a quasi-continuous-wave (QCW) diode-pumped passively Q-switched Nd:YVO(4) laser with an intracavity optical parametric oscillator (OPO). With a diode-pumping energy of 35 mJ, the output pulse energy and the pulse width at 1573 nm are found to be 1.58 mJ and 26 ns, respectively. The pulse repetition rate can be up to 100 Hz with the overall OPO beam quality M(2) factor to be better than 1.5.
Millijoule intracavity OPO driven by a passively Q-switched Nd:YVO4 laser with AlGaInAs quantum-well saturable absorber
(2011-09-01)
Huang, Y. P.
;
Chiang, P. Y.
;
Chen, Y. F.
;
Huang, K. F.
;
電子物理學系
We originally demonstrate the use of an AlGaInAs periodic quantum-well absorber to achieve a quasi-continuous-wave (QCW) diode-pumped passively Q-switched Nd:YVO4 laser with an intracavity optical parametric oscillator (OPO). With a diode-pumping energy of 35 mJ, the output pulse energy and the pulse width at 1573 nm are found to be 1.58 mJ and 26 ns, respectively. The pulse repetition rate can be up to 100 Hz with the overall OPO beam quality M-2 factor to be better than 1.5.
Millijoule-level Yb-doped photonic crystal fiber laser passively Q-switched with AlGaInAs quantum wells
(2010-12-20)
Zhuang, W. Z.
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Huang, W. C.
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Chiang, P. Y.
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Su, K. W.
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Huang, K. F.
We report on a millijoule-level Yb-doped photonic crystal fiber (PCF) laser passively Q-switched with AlGaInAs quantum wells (QWs). Three types of AlGaInAs devices with different QW numbers are fabricated to investigate the performance. With 50 groups of three AlGaInAs QWs as a saturable absorber (SA), the PCF laser generates an average power of 7.1 W with a pulse repetition rate of 6.5 kHz at a pump power of 16 W, corresponding to the pulse energy of 1.1 mJ. The maximum peak power is up to 110 kW. (C) 2010 Optical Society of America
Non-paraxial contributions to the far-field pattern of surface-emitting lasers: a manifestation of the momentum-space wavefunctions of quantum billiards
(2011-07-01)
Yu, Y. T.
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Huang, Y. J.
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Chiang, P. Y.
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Lin, Y. C.
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Huang, K. F.
We investigated experimentally non-paraxial contributions to the high-order far-field pattern of large-area vertical-cavity surface-emitting lasers in order to explore by analogy the momentum-space wave distributions of quantum billiards. Our results reveal that non-paraxial contributions significantly influence the morphology of the high-order far-field pattern. A fast reliable method is developed for transforming the experimental far-field patterns to the correct Fourier transform of the corresponding near-field lasing modes. In this way we visualize the momentum-space (p-q) wavefunctions of quantum billiards.
Resolving the formation of modern Chladni figures
(2015-09-01)
Tuan, P. H.
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Tung, J. C.
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Liang, H. C.
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Chiang, P. Y.
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Huang, K. F.
The resonant spectrum of a thin plate driven with a mechanical oscillator is precisely measured to distinguish modern Chladni figures (CFs) observed at the resonant frequencies from classical CFs observed at the non-resonant frequencies. Experimental results reveal that modern CFs generally display an important characteristic of avoided crossings of nodal lines, whereas the nodal lines of classical CFs form a regular grid. The formation of modern CFs and the resonant frequency spectrum are resolved with a theoretical model that characterizes the interaction between the plate and the driving source into the inhomogeneous Kirchhoff-Love equation. The derived formula for determining resonant frequencies is shown to be exactly identical to the meromorphic function given in singular billiards that deals with the coupling strength on the transition between integrable and chaotic features. The good agreement between experimental results and theoretical predictions verifies the significant role of the strong-coupling effect in the formation of modern CFs. More importantly, it is confirmed that the apparatus for generating modern CFs can be developed to serve as an expedient system for exploring the nodal domains of chaotic wave functions as well as the physics of the strong coupling with a point scatterer. Copyright (C) EPLA, 2015
Simultaneous self-mode-locking of TEM(0,0) and TEM(1,0) modes in a Nd:YVO(4) laser: Application for measuring the thermal focal length
(2011-03-01)
Liang, H. C.
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Chiang, P. Y.
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Huang, Y. J.
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Lin, Y. C.
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Chen, Y. F.
We demonstrate that the simultaneous self-mode-locking of TEM(0,0) and TEM(1,0) modes can be achieved in a standard end-pumped Nd:YVO(4) laser. With this simultaneous self-mode-locking, the transverse beat frequency can be accurately measured as a function of the absorbed power. We employ the measured beat frequency and the cavity theory to precisely determine the effective focal length of the thermal lens in the gain medium.
Simultaneous self-mode-locking of TEM0,0 and TEM1,0 modes in a Nd:YVO4 laser: Application for measuring the thermal focal length
(2011-03-01)
Liang, H. C.
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Chiang, P. Y.
;
Huang, Y. J.
;
Lin, Y. C.
;
Chen, Y. F.
We demonstrate that the simultaneous self-mode-locking of TEM0,0 and TEM1,0 modes can be achieved in a standard end-pumped Nd:YVO4 laser. With this simultaneous self-mode-locking, the transverse beat frequency can be accurately measured as a function of the absorbed power. We employ the measured beat frequency and the cavity theory to precisely determine the effective focal length of the thermal lens in the gain medium.