Browsing by Author "Wu, Tzeng-Tsong"

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Blue GaN-based surface-emitting lasers incorporating a sub-wavelength high contrast grating
(2013-01-01)
Wu, Tzeng-Tsong
;
Wu, Shu-Hsien
;
Chen, Hao-Wen
;
Lu, Tien-Chang
;
Wang, Shing-Chung
Blue GaN-based surface-emitting lasers incorporating a sub-wavelength high contrast grating were reported. The laser characteristics such as threshold energy, degree of polarization and divergence angle were measured to be 0.56 mJ/cm(2), 73% and 12 degrees. (C) 2013 Optical Society of America
Characteristics of an Electrically Pumped GaN-based Microcavity Light Emitter with an AlN Current Blocking Layer
(2012)
Cheng, Bo-Siao
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Wu, Tzeng-Tsong
;
Lai, Ying-You
;
Wu, Yun-Lin
;
Chen, Cheng-Hung
We demonstrate a GaN-based microcavity light emitter (MCLE) with an AlN current blocking layer. An AlN layer is inserted on the InGaN/GaN multiple quantum wells as a current blocking layer and an optical confinement layer. (C)2011 Optical Society of America
Characteristics of Current-Injected GaN-Based Vertical-Cavity Surface-Emitting Lasers
(2011-11-01)
Lu, Tien-Chang
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Wu, Tzeng-Tsong
;
Chen, Shih-Wei
;
Tu, Po-Min
;
Li, Zhen-Yu
This paper reviews the fabrication technology and performance characteristics of current-injected GaN-based vertical-cavity surface-emitting lasers (VCSELs) with hybrid distributed Bragg reflectors (DBRs). The GaN-based VCSEL consists of a ten-pair Ta(2)O(5)/SiO(2) top DBR, a 7 lambda-thick optical cavity embedded with 10 InGaN/GaN multiquantum wells, and a 29-pair AlN/GaN bottom DBR. Lasing action is observed under continuous-wave operation at room temperature. The laser characteristics, such as temperature-dependent laser threshold current, emission wavelength, and spontaneous emission coupling factors, have been measured and discussed.
Characteristics of GaN-Based Photonic Crystal Surface Emitting Lasers with Central Defects
(2012)
Wu, Tzeng-Tsong
;
Weng, Peng-Hsiang
;
Hou, Yen-Ju
;
Lu, Tien-Chang
;
光電工程學系
The GaN-based Photonic crystal surface emitting lasers (PCSELs) with different central defects were fabricated and investigated. The characteristics for PCSELs with different central defects were calculated and matched well with experimental results. (c) 2011 Optical Society of America
Characteristics of GaN-based Vertical Cavity Surface Emitting Lasers with Hybrid Mirrors
(2011)
Lu, Tien-Chang
;
Cheng, Bo Siao
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Wu, Tzeng-Tsong
;
Chen, Shih-Wei
;
Chen, Chien-Kang
We demonstrated CW current injection of GaN VCSELs with hybrid mirrors at room temperature. The laser characteristics, such as temperature dependent laser threshold current, spontaneous emission coupling factors, have been measured and discussed. (C)2011 Optical Society of America
Continuous wave operation of current injected GaN vertical cavity surface emitting lasers at room temperature
(2010-08-16)
Lu, Tien-Chang
;
Chen, Shih-Wei
;
Wu, Tzeng-Tsong
;
Tu, Po-Min
;
Chen, Chien-Kang
We report the demonstration of the continuous wave laser action on GaN-based vertical cavity surface emitting lasers at room temperature. The laser structure consists of a ten-pair Ta(2)O(5)/SiO(2) distributed Bragg reflector (DBR), a 7 lambda-thick optical cavity, ten-pairs InGaN/GaN multiquantum wells with an AlGaN electron blocking layer, and a 29-pair AlN/GaN DBR. The laser has a threshold current of about 9.7 mA corresponding to the current density of about 12.4 kA/cm(2) and a turn-on voltage about 4.3 V at 300 K. The lasing wavelength was 412 nm with a linewidth of about 0.5 nm. A spontaneous emission coupling efficiency factor of about 5x10(-3) and the degree of polarization of about 55% were measured, respectively. The laser beam has a narrow divergence angle of about 8 degrees. (C) 2010 American Institute of Physics. [doi:10.1063/1.3483133]
Design of Low-Threshold Photonic Crystal Surface-Emitting Lasers
(2012-05-15)
Hung, Chih-Tsang
;
Syu, Yu-Cheng
;
Wu, Tzeng-Tsong
;
Lu, Tien-Chang
;
光電工程學系
We have investigated the influence of various thicknesses on different layers in GaAs-based photonic crystal surface-emitting lasers (PCSELs), by using the transfer matrix and coupled wave methods to increase the vertically optical confinement factor and to reduce the threshold gain. In addition, the relationship between the threshold gain and the filling factor has been considered. This letter provides an efficient calculation method for designing square-lattice-type PCSEL structures, which shall be useful for the fabrication of low-threshold PCSELs in the near future.
Design of Low-Threshold Photonic Crystal Surface-Emitting Lasers (vol 24, pg 866, 2012)
(2012-08-01)
Hung, Chih-Tsang
;
Syu, Yu-Cheng
;
Wu, Tzeng-Tsong
;
Lu, Tien-Chang
;
光電工程學系
"Design of Low-Threshold Photonic Crystal Surface-Emitting Lasers (vol 24, pg 866, 2012)"
(1970-01-01)
Hung, Chih-Tsang
;
Syu, Yu-Cheng
;
Wu, Tzeng-Tsong
;
Lu, Tien-Chang
;
光電工程學系
Effects of Lattice Types on GaN-Based Photonic Crystal Surface-Emitting Lasers
(2015-01-01)
Wu, Tzeng-Tsong
;
Chen, Chih-Cheng
;
Lu, Tien-Chang
;
光電工程學系
;
Department of Photonics
GaN-based photonic crystal (PC) surface emitting lasers with different lattice types including hexagonal, square, and honeycomb lattice were fabricated and characterized. Laser characteristics including threshold conditions, lasing spectra, polarization, and divergence angle of devices with different lattice have been studied and discussed. The threshold energy density of the device with honeycomb, hexagonal, and square lattice was measured to be approximately 1.6, 2.3, and 3.8 mJ/cm(2) at room temperature, showing superior characteristics of applying honeycomb as PC lattice patterns. Moreover, the experimental results were matched well to the theoretical prediction using the multiple scattering method. Finally, the laser characteristics of devices with three lattice types such as divergence angle and degree of polarization (DOP) were analyzed and discussed. The device with honeycomb lattice shows low threshold, high DOP of 86%, and low divergence angle of 1.3 degrees among three lattice types, demonstrating its potential in the future surface emitting laser sources.
Enhanced Output Power of GaN-Based Resonance Cavity Light-Emitting Diodes With Optimized ITO Design
(2011-12-15)
Wu, Tzeng-Tsong
;
Lin, Chien-Chung
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Wu, Yun-Lin
;
Chen, Chien-Kang
;
Lu, Tien-Chang
We fabricated and measured GaN-based resonant cavity light-emitting diodes with a 30 nm thick Indium tin oxide (ITO) thin film as a transparent contact layer. Four different ITO structures on p-type GaN samples were deposited by sputter and e-gun, and the corresponding device performance was compared. Each of these four samples has been annealed by its optimal parameters. The ITO thin film deposited by sputter demonstrated better electrical characteristics, surface morphology, specific contact resistance, and the overall device light output compared to those of the e-gun samples. Between the two sputtered ITO types, the hybrid type shows higher roll-over current density of 14 kA/cm(2), and the output power is increased from 15 to 39 mu W. From statistical data of the 2-D light intensity under the same current, we saw the lateral current spreading of the pure crystalline ITO by sputter is worst. The hybrid type, which combines the crystalline and amorphous ITO, has the best overall performance when we consider all the electrical, optical, and metrology measurements. From these results, we believe the 30 nm thick hybrid ITO thin film has the best potential to be applied in light emitting devices such as light-emitting diodes, laser diodes, etc.
Fano resonances GaN-based high contrast grating surface-emitting lasers
(2013)
Wu, Tzeng-Tsong
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Wu, Shu-Hsien
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Lu, Tien-Chang
;
Kuo, Hao-Chung
;
Wang, Shing-Chung
GaN-based high contrast grating surface-emitting lasers (HCG SELs) with AlN/GaN distributed Bragg reflectors were reported. The device exhibited a low threshold pumping energy density of about 0.56 mJ/cm(2) and the lasing wavelength was at 393.6 nm with a high degree of polarization of 73% at room temperature. The specific lasing mode and polarization characteristics agreed well with the theoretical modeling. The low threshold characteristics of our GaN-based HCG SELs utilized by the Fano resonance can be potential for development of blue surface emitting laser sources
GaN-based high contrast grating surface-emitting lasers
(2013-02-25)
Wu, Tzeng-Tsong
;
Wu, Shu-Hsien
;
Lu, Tien-Chang
;
Wang, Shing-Chung
;
光電工程學系
GaN-based high contrast grating surface-emitting lasers (HCG SELs) with AlN/GaN distributed Bragg reflectors were reported. The device exhibited a low threshold pumping energy density of about 0.56 mJ/cm(2) and the lasing wavelength was at 393.6 nm with a high degree of polarization of 73% at room temperature. The specific lasing mode and polarization characterisitcs agreed well with the theoretical modeling. The low threshold characteristics of our GaN-based HCG SELs faciliated by the Fano resonance can serve as the best candidate in blue surface emitting laser sources. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4794081]
GaN-based photonic crystal surface emitting lasers with central defects
(2011-11-28)
Wu, Tzeng-Tsong
;
Weng, Peng-Hsiang
;
Hou, Yen-Ju
;
Lu, Tien-Chang
;
光電工程學系
The GaN-based photonic crystal surface emitting lasers (PCSELs) with different central defects were fabricated and investigated. The threshold energy densities increased from 3.23 to 3.51 mJ/cm(2) when the central defect size increased. In addition, lasing wavelengths decreased from 400 nm to 390 nm due to the guided mode shifting phenomenon for the PCSEL cavities with larger central defects. The tendency of threshold gain and resonance wavelength for PCSELs with different central defects were calculated by the multiple scattering method and well matched to the experimental results. (C) 2011 American Institute of Physics. [doi:10.1063/1.3665251]
GaN-based surface-emitting lasers using high contrast grating
(2014)
Lu, Tien-Chang
;
Wang, Shing-Chung
;
Wu, Tzeng-Tsong
;
Wu, Shu-Hsien
;
Syu, Yu-Cheng
GaN-based surface-emitting lasers (SELs) using high contrast grating (HCG) with AlN/GaN distributed Bragg reflectors were reported. The laser device achieved a threshold energy density of about 0.56 mJ/cm(2) and the lasing wavelength was at 393.6 nm with a high degree of polarization of 73% at room temperature. The resonant mode and polarization characteristics matched to the theoretical prediction. GaN-based SELs using HCG supported by the Fano resonance can be potential for development of blue surface emitting laser sources
High quality factor nonpolar GaN photonic crystal nanocavities
(2013-05-13)
Wu, Tzeng-Tsong
;
Lo, Sheng-Yun
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Huang, Huei-Min
;
Tsao, Che-Wei
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Lu, Tien-Chang
High quality factor a-plane nonpolar GaN two-dimensional photonic crystal (PC) nanocavities on r-plane sapphire substrates have been demonstrated. Nonpolar GaN PC nanocavities on a thin membrane structure were realized by using e-beam lithography to define the PC patterns and focused-ion beam milling to fabricate the suspended thin membrane. A dominant resonant mode at 388 nm with a high quality factor of approximately 4300 has been demonstrated at 77K by the micro-photoluminescence system. Moreover, the degree of polarization of the emission from the non-polar GaN PC nanocavity was measured to be 64% along the m crystalline direction. (C) 2013 AIP Publishing LLC.
Light emission characteristics of nonpolar a-plane GaN-based photonic crystal defect cavities
(2015-01-01)
Kao, Tsung Sheng
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Wu, Tzeng-Tsong
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Tsao, Che-Wei
;
Lin, Jyun-Hao
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Lin, Da-Wei
In this paper, nonpolar a-plane GaN-based photonic crystals (PCs) with different defect cavities have been demonstrated. By using a micro-photoluminescence (mu-PL) system operated at 77 K, the dominant resonant modes of the GaN-based PC defect cavities show high quality factor (Q) values in the light emission performance which can be up to 4.3x10(3). Moreover, the degree of polarization (DOP) of the light emission from the nonpolar GaN-based PC defect cavities was measured to achieve around 64 % along the m crystalline direction.
Light Emission Characteristics of Nonpolar a-Plane GaN-Based Photonic Crystal Defect Cavities
(2016-09)
Kao, Tsung Sheng
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Wu, Tzeng-Tsong
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Tsao, Che-Wei
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Lin, Jyun-Hao
;
Lin, Da-Wei
In this paper, the light emission performance from nonpolar a-plane gallium nitride (GaN)-based photonic crystal (PC) slabs with line-type defect cavities has been investigated. Via the focused ion beam milling technique, thin membrane structures of the nonpolar GaN PC defect cavities were engineered, exhibiting one dominated resonant mode occurred at 419.3 nm with a high quality factor of 1.9 x 10(3) in the photoluminescence emission characterizations. In the far-field region, light emission performance shows a high polarization degree of 50% with the beam direction perpendicular to the defect cavity. Compared with the PC defect cavity patterns fabricated on c-axial oriented GaN materials, the a-plane PC defect cavities display not only the linear light output-input power dependence, but also an invariant resonant mode of constant light emission behavior with increasing the injection carriers, therefore providing a new perspective for the future development of promising optoelectronic devices.
Localized Lasing Mode in GaN Quasi-Periodic Nanopillars at Room Temperature
(2013-07-01)
Wu, Tzeng-Tsong
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Chen, Chih-Cheng
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Chen, Hao-Wen
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Lu, Tien-Chang
;
Wang, Shing-Chung
In this paper, GaN quasi-periodic nanopillars were fabricated and investigated. The quasi-periodic nanopillars were realized by nanoimprint technique and selective area growth. Localized lasing mode was identified in the GaN quasi-periodic nanopillars. The threshold energy density and lasing wavelength were 40 mJ/cm(2) and 369 nm, respectively. The divergence angle and near-field lasing spot were measured to be 10.5 degrees and 3.6 mu m, respectively. The spontaneous emission coupling factor of localized lasing mode was estimated to be 9.4 x 10(-3). The mode patterns in the real and reciprocal spaces were calculated by the multiple scattering method to confirm the mode localization behavior.
Mode Localization in Defect-free GaN-based Bottom-up Photonic Quasicrystal Lasers
(2012)
Wu, Tzeng-Tsong
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Chen, Chih-Cheng
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Chen, Hao-Wen
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Lu, Tien-Chang
;
Wang, Shing-Chung
GaN-based bottom-up photonic quasicrystal (PQC) lasers were realized and characterized. Photonic quasicrystal nanopillars were realized by nanoimprint technique and selective area growth. Highly localized mode was identified for the first time in GaN-based PQC lasers. (C) 2012 Optical Society of America