Browsing by Author "Huang, S. C."

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A Novel InGaN Blue Light-Emitting Diode with a Self-Textured Oxide Mask Structure
(2011-01-01)
Lin, W. Y.
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Wuu, D. S.
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Huang, S. C.
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Lo, S. Y.
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Liu, C. M.
A 460 nm InGaN/GaN blue light-emitting diode (LED) with a self-textured oxide mask (STOM) structure was fabricated and demonstrated. The design of the STOM on the GaN/sapphire substrate could be used to reduce the threading dislocation density in the epitaxial template and enhance the light extraction efficiency via the light scattering or deflection from the corrugated STOM. Under an injection current of 20 mA, the forward voltage of the STOM-LED and conventional LED (C-LED) was nearly identical at 3.41 V. Moreover, the leakage current of the STOM-LED was lower than the C-LED. Furthermore, the light output power of the STOM-LED was approximately 43% higher (at 20 mA) than the C-LED. This significant improvement was attributed to the enhanced light extraction via the STOM array.
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 1.3-mu m laser by a diode-pumped actively Q-switched Nd : GdVO4 laser - art. no. 68712K
(2008)
Huang, S. C.
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Su, K. W.
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Li, A.
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Liu, S. C.
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Chen, Y. F.
We report a high-peak-power AlGaInAs 1.36-mu m vertical-external-cavity surface-emitting laser (VECSEL) optically pumped by a diode-pumped actively Q-switched Nd:GdVO4 1.06-mu m laser under room-temperature operation. The gain medium is an AlGaInAs quantum wells (QWs)/barrier structure grown on a Fe-doped InP substrate by metalorganic chemical-vapor deposition. With an average pump power of 1.9 W, an average output power of 340 mW was obtained at a pulse repetition rate of 40 kHz, corresponding to an optical-to-optical conversion efficiency of 18.76%. With a peak pump power of 7.9 kW, the highest peak output power was 1.3 kW at a pulse repetition rate of 10 kHz.
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.
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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.
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
Diode-pumped passively mode-locked 1342 nm Nd:YVO4 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:YVO4 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
Efficient high-peak-power AlGaInAs eye-safe wavelength disk laser with optical in-well pumping
(2009-07-06)
Chang, H. L.
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Huang, S. C.
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Chen, Yi-Fan
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Su, K. W.
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Chen, Y. F.
We have demonstrated an efficient high-peak-power AlGaInAs eye-safe wavelength disk laser at 1555 nm. The quantum defect and the thermal load are significantly reduced by pumping the quantum well directly. The overall conversion efficiency is enhanced over three times compared with the barrier pumping method. With a pump peak power of 3.7 kW, an output peak power of 0.52 kW is generated at a pulse repetition rate of 20 kHz. (C) 2009 Optical Society of America
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."
Growth and characterization of Ge nanostructures selectively grown on patterned Si
(2008-11-03)
Cheng, M. H.
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Ni, W. X.
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Luo, G. L.
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Huang, S. C.
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Chang, J. J.
By utilizing different distribution of strain fields around the edges of oxide, which are dominated by a series of sizes of oxide-patterned windows, long-range ordered self-assembly Ge nanostructures, such as nano-rings, nano-disks and nano-dots, were selectively grown by ultra high vacuum chemical vapor deposition (UHV-CVD) on Si (001) substrates. High-resolution double-crystal symmetrical omega/2 theta scans and two-dimensional reciprocal space mapping (2D-RSM) technologies employing the triple axis X-ray diffractometry have been used to evaluate the quality and strain status of as-deposited as well as in-situ annealed Ge nanostructures. Furthermore, we also compare the quality and strain status of Ge epilayers grown on planar unpatterned Si substrates. It was found that the quality of all Ge epitaxial structures is improved after in-situ annealing process and the quality of Ge nano-disk structures is better than that of Ge epilayers; on planar unpatterned Si substrates, because oxide sidewalls are effective dislocation sinks. We also noted that the degree of relaxation for as-deposited Ge epilayers on planar unpatterned Si substrates is less than that for as-deposited Ge nano-disk structures. After in-situ annealing process,all Ge epitaxial structures are almost at full relaxation whatever Ge epitaxial structures grew on patterned or unpatterned Si substrates. (c) 2008 Published by Elsevier B.V.
Growth Parameters Optimization of GaN High Electron Mobility Transistor Structure on Silicon Carbide Substrate
(2014-01-01)
Wong, Y. Y.
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Huang, S. C.
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Huang, W. C.
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Lumbantoruan, F.
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Chiu, Y. S.
High electron mobility transistors heterostructures of AlGaN/GaN were grown by metalorganic chemical vapor deposition system on silicon carbide substrate. The growth parameters such as AlN buffer thickness, AlN spacer growth time and Al content in AlGaN barrier layer were optimized. Moreover, the effects of chamber pressure and V/III ratio at the initial growth state of GaN on film crystal quality were also investigated. The optimized AlGaN/GaN heterostructure has AlN buffer thickness of 120 nm, AlN spacer growth time of 10 s and Al content of 28% in the barrier layer. Furthermore, as a result of using higher chamber pressure and lower V/III, both the GaN crystal quality and electron mobility in the AlGaN/GaN were also significantly improved. After the growth parameter optimization, the GaN (002) and (102) planes exhibited X-ray rocking curve widths of 209 arcsec and 273 arcsec, respectively. Besides, the AlGaN/GaN structure also has an electron mobility of 1832 cm(2)/V-s and a sheet electron density of 1.08 10(13) cm(-2), which yielding a sheet resistance of 316 Omega/sq.
High efficiency light emitting diode with anisotropically etched GaN-sapphire interface
(2009-07-27)
Lo, M. H.
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Tu, P. M.
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Wang, C. H.
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Hung, C. W.
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Hsu, S. C.
We report the fabrication and study of high efficiency ultraviolet light emitting diodes with inverted micropyramid structures at GaN-sapphire interface. The micropyramid structures were created by anisotropic chemical wet etching. The pyramid structures have significantly enhanced the light output efficiency and at the same time also improved the crystal quality by partially relieving the strain and reducing the dislocation defects in GaN. The electroluminescent output power at normal direction was enhanced by 120% at 20 mA injection current and the output power integrated over all directions was enhanced by 85% compared to a reference sample.
High-peak-power flashlamp-pumped passively Q-switched Nd : YAG laser with AlGaInAs quantum wells as a saturable absorbers - art. no. 68712M
(2008)
Liang, H. C.
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Huang, J. Y.
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Huang, S. C.
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Su, K. W.
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Chen, Y. F.
We demonstrate an AlGaInAs saturable absorber with a periodic quantum wells (QWs)/barrier structure that can be used to achieve an efficient high-peak-power and high-pulse-energy passively flashlamp-pumped Q-switched Nd:YAG laser at 1.06 um. 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 voltage of 14.5 J, a single pulse was generated with a pulse energy of 14 mJ and a Q-switched pulse width of 13 ns. The maximum peak power was greater than 1.08 MW.
Improved output power of GaN-based ultraviolet light-emitting diodes with sputtered AlN nucleation layer
(2015-03-15)
Chiu, C. H.
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Lin, Y. W.
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Tsai, M. T.
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Lin, B. C.
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Li, Z. Y.
In this work, the ultraviolet light emitting diodes (UV -LEDs) at 380 no were grown on patterned sapphire substrate (PSS) by atmospheric pressure metal organic chemical vapor deposition (AP-MOCVD). A sputtered AlN nucleation layer was utilized on the PSS to enhance the quality of the epitaxial layer. By using high resolution X-ray diffraction, the full width at half maximum of the rocking curve shows that the UV-LEDs with sputtered AlN nucleation layer had better crystalline quality when compared to conventional GaN nucleation samples. From the scanning electron microscope (SEM) and transmission electron microscopy (TEM) images, it can be observed that the Lip and sidewall portion of the pattern was smooth using the sputtered AlN nucleation layer. The threading dislocation densities (TDDs) are reduced from 6 x 107 cm(-2) to 2.5 x 107 cm(-2) at the interface between the u-GaN layers for conventional and AlN PSS devices, respectively. As a result, a much higher light output povver was achieved. The light output power at an injection current of 20 mA was enhanced by 30%. Further photoluminescence (PL) measurement and numerical simulation confirm that this increase or output power can be attributed to the improvement of material quality and light extraction. (C) 2014 Elsevier B.V. All rights reserved.
InGaAsP quantum-wells saturable absorber for diode-pumped passively Q-switched 1.3-mu m lasers
(2006-09-01)
Li, A.
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Liu, S. C.
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Su, K. W.
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Liao, Y. L.
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Huang, S. C.
We demonstrate the first use of InGaAsP quantum wells as a saturable absorber in the Q-switching of a diode-pumped Nd-doped 1.3 mu m laser. The barrier layers of the InGaAsP quantum-well device are designed to be a strong absorber for the suppression of the transition channel at 1.06 mu m. With an incident pump power of 1.8 W, an average output power of 160 mW with a Q-switched pulse width of 19 ns at a pulse repetition rate of 38 kHz was obtained.
Low-temperature study of lasing characteristics for 1.3-mu m AlGaInAs quantum-well laser pumped by an actively Q-switched Nd:YAG laser
(2010)
Su, K. W.
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Chen, Yi-Fan
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Huang, S. C.
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Li, A.
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Liu, S. C.
We report a low-temperature 1.3 mu m AlGaInAs quantum-well laser pumped by a 1.06 mu m active Q-switched laser quenched by a low-temperature vacuum system. An average power of 330mW is achieved at temperature as low as 233K compared to the average power of 50mW obtained at room-temperature without cooling device both at pumping repetition rate of 30 kHz. And the average rate of gain peak shift was found to be 0.47 nm/K between 293-133 K.
Passive Q switching of Er-Yb fiber laser with semiconductor saturable absorber
(2008-03-03)
Huang, J. Y.
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Huang, S. C.
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Chang, H. L.
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Su, K. W.
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Chen, Y. F.
A high-performance A1GaInAs quantum-well saturable absorber is developed for passively Q-switched Er-Yb double-clad fiber lasers at 1560 nm. With an incident pump power of 13.5 W, an average output power of 1.26 W with a pulse repetition rate of 12 kHz is obtained. The maximum peak power is greater than 500 W. (C) 2008 Optical Society of America.
Power scale-up of high-pulse-energy passively Q-switched Nd:YLF laser: influence of negative thermal lens enhanced by upconversion
(2012)
Huang, Y. J.
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Tang, C. Y.
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Huang, Y. P.
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Huang, S. C.
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Su, K. W.
"We develop a practical method to extend the power scale-up for a laser in a concave-plano cavity to be influenced by a large negative thermal lens. With the developed method, we successfully scale up the output power of a compact high-pulse-energy passively Q-switched Nd:YLF laser at 1053 nm with the Cr4+:YAG crystal as a saturable absorber. At an incident pump power of 12.6 W, the maximum output power under the optimum operation at 1053 nm reaches 2.61 W with a pulse width of 6 ns and a pulse repetition rate of 4.6 kHz. More importantly, we experimentally verify that the energy-transfer upconversion significantly enhances the negative focal length of thermal lens in the passively Q-switched Nd:YLF laser. (C) 2012 by Astro, Ltd."
The joint usage of conventional medicine and alternative medicine for migraine in Taiwan: a ten-year retrospective study
(2009-10-01)
Chang, S. C.
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Hou, M. C.
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Hu, N. Z.
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Lo, L. C.
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Chen, Y. L.