Browsing by Author "Huang, Y. P."

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> 100-kW linearly polarized pulse fiber amplifier seeded by a compact efficient passively Q-switched Nd:YVO4 Laser
(2012-11-01)
Zhuang, W. Z.
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Huang, W. C.
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Cho, C. Y.
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Huang, Y. P.
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Huang, J. Y.
We thoroughly develop compact high-peak-power Nd:YVO4/Cr4+:YAG passively Q-switched lasers (PQS) as the seed source of the fiber amplifier. We exploit a nearly hemispherical cavity to reach the second threshold criterion and systematically consider the thermal lensing effect and the mode-size matching in the overall optimization. Employing a Cr4+:YAG absorber with 70% initial transmission, we obtain a 50-kHz seed pulse train with the pulse duration of 4.8 ns and the pulse energy of 22 mu J at a pump power of 5.4 W. Injecting this seed laser into a polarization maintained Yb-doped fiber, the pulse energy and peak power at a pump power of 16 W are enhanced up to 178 mu J and 37 kW, respectively. We also use an absorber with 40% initial transmission to generate a 25 kHz pulse train with the pulse duration of 1.6 ns and the pulse energy of 36 mu J at a pump power of 5.4 W. With this seed laser, we find that the surface damage of the fiber limits the maximum pulse energy and peak power to be 192 mu J and 120 kW, respectively.
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.
Brain-Display Interactive System by Using Steady-State Visual Evoke Potential(SSVEP) Stimulation
(2014-01-01)
Huang, Y. P.
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Chien, Y. Y.
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Lin, F. C.
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Zao, J. K.
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Wang, Y.
Steady-state visual evoked potential (SSVEP) is one of the most effective modalities for brain-computer interaction. However, its flickering visual stimuli may cause discomfort, even induce migraine and seizure attacks among its viewers. This paper presents a novel approach to induce SSVEP with high signal-to-noise ratios (SNRs) using composite color lights flickering near or above its critical flicker fusion (CFF) thresholds. Different combinations of frequencies, relative phases and pulse widths of the stimuli waveforms were tested for their effectiveness to produce high SNR values among their SSVEP responses. Results of our experiments were analyzed and studied. The rationale behind the special design of high-frequency polychromatic stimuli and the implications towards the development of an effective brain-display interaction (BDI) system were also discussed.
Compact high-pulse-energy passively Q-switched Nd:YLF laser with an ultra-low-magnification unstable resonator: application for efficient optical parametric oscillator
(2013-01-28)
Cho, C. Y.
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Huang, Y. P.
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Huang, Y. J.
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Chen, Y. C.
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Su, K. W.
We exploit an ultra-low-magnification unstable resonator to develop a high-pulse-energy side-pumped passively Q-switched Nd:YLF/Cr4+:YAG laser with improving beam quality. A wedged laser crystal is employed in the cavity to control the emissions at 1047 nm and 1053 nm independently through the cavity alignment. The pulse energies at 1047 nm and 1053 nm are found to be 19 mJ and 23 mJ, respectively. The peak powers for both wavelengths are higher than 2 MW. Furthermore, the developed Nd:YLF lasers are employed to pump a monolithic optical parametric oscillator for confirming the applicability in nonlinear wavelength conversions. (C) 2013 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
Comparison of thermal lensing effects between single-end and double-end diffusion-bonded Nd:YVO(4) crystals for (4)F(3/2)->(4)I(11/2) and (4)F(3/2)->(4)I(13/2) transitions
(2008-12-08)
Chang, Y. T.
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Huang, Y. P.
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Su, K. W.
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Chen, Y. F.
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電子物理學系
The effective focal lengths of thermal lens in diode-end-pumped continuous-wave Nd:YVO(4) lasers for the (4)F(3/2)->(4)I(11/2) and (4)F(3/2)->(4)I(13/2) transitions were determined. The experimental results revealed that the thermal lensing effect for the (4)F(3/2)->(4)I(11/2) transition can be sufficiently improved by employing a single-end diffusion-bonded Nd: YVO4 crystal replacing a conventional Nd: YVO4 crystal. However, using a double-end diffusion-bonded Nd: YVO4 crystal was a great improvement over a single-end diffusion-bonded Nd: YVO4 crystal for the (4)F(3/2)->(4)I(13/2) transition with stronger thermal lensing effect. (C) 2008 Optical Society of America
Diode-pumped multi-frequency Q-switched laser with intracavity cascade Raman emission
(2008-05-26)
Chang, Y. T.
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Huang, Y. P.
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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 diode-pumped actively Q-switched mixed Nd:Y0.3Gd0.7VO4 laser with an intracavity KTP crystal is developed to produce cascade SRS emission up to the fourth order. With an incident pump power of 14 W and a repetition rate of 50 kHz, the average output powers at the first, second, third and fourth Stokes modes are approximately 0.05 W, 0.61 W, 0.25 W, and 0.11 W, respectively. The maximum peak power is greater than 2 kW. (C) 2008 Optical Society of America.
Effects of semiconductor processing chemicals on conductivity of graphene
(2012-07-01)
Chen, Chung Wei
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Ren, F.
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Chi, Gou-Chung
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Hung, S. C.
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Huang, Y. P.
"Graphene layers on SiO2/Si substrates were exposed to chemicals or gases commonly used in semiconductor fabrication processes, including solvents (isopropanol, acetone), acids, bases (ammonium hydroxide), UV ozone, H2O, and O-2 plasmas. The recovery of the initial graphene properties after these exposures was monitored by measuring both the layer resistance and Raman 2D peak position as a function of time in air or vacuum. Solvents and UV ozone were found to have the least affect, while oxygen plasma exposure caused an increase of resistance of more than 3 orders of magnitude. Recovery is accelerated under vacuum but changes can persist for more than 5 h. Careful design of fabrication schemes involving graphene is necessary to minimize these interactions with common processing chemicals. (C) 2012 American Vacuum Society. [http://dx.doi.org/10.1116/1.4732517]"
Efficient high-energy pulse generation from a diode-side-pumped passively Q-switched Nd:YAG laser and application for optical parametric oscillator
(2014-09-01)
Huang, Y. P.
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Huang, Y. J.
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Cho, C. Y.
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電子物理學系
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Department of Electrophysics
We employ a convex-concave resonator to develop a high-pulse-energy diode-side-pumped passively Q-switched Nd:YAG laser with high extraction efficiency. At a diode pump energy of 227 mJ, the output laser pulse reaches 30 mJ with a pulse width of 6 ns at a repetition rate of 20 Hz. The optical-to-optical conversion efficiency is up to 13.2%. Based on the developed Nd:YAG laser oscillator, we further employ a monolithic KTP crystal to perform the optical parametric oscillator (OPO). With the 1064 nm input energy of 30 mJ, the OPO energy at 1573 nm is found to be 13.3 mJ, corresponding to an OPO conversion efficiency as high as 44.3%.
Efficient high-energy pulse generation from a diode-side-pumped passively Q-switched Nd:YAG laser and application for optical parametric oscillator
(2014-09-01)
Huang, Y. P.
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Huang, Y. J.
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Cho, C. Y.
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電子物理學系
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Department of Electrophysics
We employ a convex-concave resonator to develop a high-pulse-energy diode-side-pumped passively Q-switched Nd:YAG laser with high extraction efficiency. At a diode pump energy of 227 mJ, the output laser pulse reaches 30 mJ with a pulse width of 6 ns at a repetition rate of 20 Hz. The optical-to-optical conversion efficiency is up to 13.2%. Based on the developed Nd:YAG laser oscillator, we further employ a monolithic KTP crystal to perform the optical parametric oscillator (OPO). With the 1064 nm input energy of 30 mJ, the OPO energy at 1573 nm is found to be 13.3 mJ, corresponding to an OPO conversion efficiency as high as 44.3%.
Efficient high-pulse-energy eye-safe laser generated by an intracavity Nd:YLF/KTP optical parametric oscillator: role of thermally induced polarization switching
(2012)
Huang, Y. J.
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Tang, C. Y.
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Huang, Y. P.
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Cho, C. Y.
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Su, K. W.
A high-pulse-energy eye-safe laser at 1552 nm is effectually generated by an intracavity Nd:YLF/KTP optical parametric oscillator (OPO) with the help of the thermally induced polarization switching. The polarization characteristics of the c-cut Nd:YLF laser at 1053 nm in the continuous-wave (CW) and Q-switched operation are comprehensively investigated. We experimentally verify the thermally induced birefringence can lead to a polarization switching between the mutually orthogonal components of the fundamental pulses. Consequently, an efficient intracavity nonlinear frequency conversion can be achieved in an optically isotropic laser crystal without any additional polarization control. With this finding, the pulse energy and peak power of the compact Nd: YLF/KTP eye-safe laser under an incident pump power of 12.7 W and a pulse repetition rate of 5 kHz are up to 306 mu J and 4 kW, respectively.
Efficient passively Q-switched Nd:YLF TEM00-mode laser at 1053 nm: selection of polarization with birefringence
(2012-08-01)
Huang, Y. J.
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Tang, C. Y.
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Lee, W. L.
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Huang, Y. P.
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Huang, S. C.
"The natural birefringence of the Nd:YLF crystal is utilized to achieve a reliable TEM00-mode linearly polarized laser at 1053 nm in a compact concave-plano resonator. The efficient selection of the polarization relies on the combined effect of the difference in diffraction angle for sigma- and pi-polarization of a wedged laser crystal and the alignment sensitivity of an optical resonator. We further employ a Cr4+:YAG saturable absorber to perform the passively Q-switched operation. At an incident pump power of 12 W, the maximum average output power is up to 2.3 W with a pulse repetition rate of 8 kHz and a pulse width of 9 ns. The pulse energy and peak power are found to be 288 mu J and 32 kW, respectively."
High-peak-power passively Q-switched Nd : YAG laser at 946 nm
(2008-06-01)
Huang, Y. P.
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Su, K. W.
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Li, A.
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Chen, Y. F.
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Huang, K. F.
We demonstrate a high-peak-power quasi-continuous-wave diode-pumped passive Q-switched Nd:YAG laser at 946 nm. We make a thorough comparison of the output performance between the saturable absorbers of InGaAs quantum wells (QWs) and a Cr4+:YAG crystal. Experimental results reveal that the saturable absorber of InGaAs QWs is superior to the Cr4+:YAG crystal because of the low nonsaturable losses and leads to a pulse energy of 330 mu J with a peak power greater than 11 kW.
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-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.
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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: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%.
High-repetition-rate quasi-CW side-pumped mJ eye-safe laser with a monolithic KTP crystal for intracavity optical parametric oscillator
(2014-04-07)
Cho, C. Y.
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Chen, Y. C.
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Huang, Y. P.
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Huang, Y. J.
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Su, K. W.
We demonstrate a high-repetition-rate millijoule passively Q-switched eye-safe Nd:YVO4 laser pumped by a quasi-CW diode stack. A theoretical analysis has been explored for the design criteria of generating TEMn,0 mode in the diode-stack directly side-pumping configuration. We successfully generate TEMn,0 modes at 1064 nm by adjusting the gain medium with respected to the laser axis. We further observe the spatial cleaning ability for generating an nearly TEM0,0 mode output at 1573 nm with a monolithic OPO cavity. At the repetition rate up to 200 Hz, the output pulse energy reaches 1.21 mJ with the threshold pump energy of 17.9 mJ. (C) 2014 Optical Society of America
Improvement of stability and efficiency in diode-pumped passively Q-switched intracavity optical parametric oscillator with a monolithic cavity
(2012)
Huang, J. Y.
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Zhuang, W. Z.
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Huang, Y. P.
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Huang, Y. J.
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Su, K. W.
We improve the performance of intracavity optical parametric oscillator (IOPO) pumped by a diode-pumped Q-switched Nd:YVO4/Cr4+:YAG laser. The IOPO cavity is formed independently by a monolithic KTP crystal that the mirrors are directly deposited on top of the nonlinear crystal. We study the performances of this IOPO cavity with different reflectivity of the output coupler at 1.5 mu m (R-s) of 80 and 50%. The average power of 1.5 mu m is up to 3.3 W at the maximum pump power of 16.8Wfor both cases. The diode-to-signal conversion efficiency is up to 20%, which is the highest one for IOPOs to our best knowledge. At the maximum pump power, the pulse energies are 41 mu J with the pulse width of 3 ns at a pulse repetition rate (PRR) of 80 kHz for R-s = 80% and 51 mu J with the pulse width of 1.2 ns at a PRR of 65 kHz for R-s = 50%, respectively. The pulse amplitude fluctuations in standard deviation are 2.6% for R-s = 80% and 4% for R-s = 50%, respectively. [GRAPHICS] (C) 2012 by Astro, Ltd.
Influence of output coupling on the performance of a passively Q-switched Nd:YAG laser with intracavity optical parametric oscillator
(2013-03-25)
Huang, Y. P.
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Huang, Y. J.
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Cho, C. Y.
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Chen, Y. F.
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電子物理學系
A singly-resonant intracavity optical parametric oscillator (OPO), pumped by a passively Q-switched Nd:YAG laser, is systematically investigated by means of a series of the output mirrors with various reflectivities for the fundamental wavelength at 1064 nm. Experimental results reveal that the output mirror with partial reflectivity instead of high reflection at 1064 nm not only is practicable to avoid the optical coatings damaged, but also enhances the dual-wavelength output efficiency for the OPO signal and fundamental laser waves. The overall optical-to-optical conversion efficiency is enhanced from 6.4% to 8.2% for the reflectivity decreasing from 99.8% to 90%. (C) 2013 Optical Society of America
Micro optical componets on transflective LCDs
(2004)
Huang, Y. P.
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Su, M. J.
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Sheih, Han-Ping. D.
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Wu, S. T.
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光電工程學系
Two micro-optical elements, image-enhanced reflector and random grating reflector, have been developed to enhance the image quality of transflective LCDs. The reflective and transmissive portions can achieve high optical efficiency, same response time and color saturation. The reflective light can has more uniform distribution and high brightness within the viewing regions. Consequently, a high image performance display under both bright and dark ambience can be achieved.