Browsing by Author "Kao, Tsung-Ting"

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Characteristics of GaN-based photonic crystal surface emitting lasers
(2008-09-15)
Lu, Tien-chang
;
Chen, Shih-Wei
;
Kao, Tsung-Ting
;
Liu, Tzu-Wei
;
光電工程學系
Characteristics of GaN-based photonic crystal surface emitting lasers (PCSELs) were investigated and analyzed. The GaN-based PCSEL emits a blue wavelength at 401.8 nm with a linewidth of 1.6 angstrom and shows a threshold energy density about 2.7 mJ/cm(2) under the optical pumping at room temperature. The lasing wavelength emitted from PCSELs with different lattice constants occurs at the calculated band edges showing different polarization angles due to the light diffracted in specific directions, corresponding exactly to Gamma, K, and M directions in the K-space. Furthermore, the PCSEL also shows a spontaneous emission coupling efficiency beta of about 5 X 10(-3) and a characteristic temperature of 148 K. (C) 2008 American Institute of Physics.
Crs
(2008)
Lu, Tien-Chang
;
Kao, Tsung-Ting
;
Chen, Shih-Wei
;
Kao, Chih-Chiang
;
Lin, Li-Fan
We report fabrication of GaN-based two-dimensional surface emitting photonic-crystal lasers and successful demonstration of lasing action at room temperature with the emission wavelength at 424.3 nm and a low threshold pumping energy density of 3.5 mJ/cm(2). (c) 2008 Optical Society of America
GaN-based high-Q vertical-cavity light-emitting diodes
(2007-10-01)
Lu, Tien-Chang
;
Kao, Tsung-Ting
;
Kao, Chih-Chiang
;
Chu, Jung-Tang
;
Yeh, Kang-Fan
We report a fabrication and demonstration of a GaN-based high-Q vertical-cavity light-emitting diode (VCLED). The GaN VCLED is composed of a 25-pair high-reflectivity (98%) GaN/AlN distributed Bragg reflector (DBR), an eight-pair SiO2/Ta2O5 dielectric DBR (99%), and a three-A optical thickness InGaN/GaN active region. It shows a very narrow linewidth of 0.52 nm, corresponding to a cavity Q-value of 895 at a driving current of 10 mA and a dominant emission peak wavelength at 465.3 nm. In addition, this VCLED emission linewidth continues to decrease with an increasing injection current, suggesting a possible realization of GaN-based vertical-cavity surface emitting lasers.
GaN-based two-dimensional surface-emitting photonic crystal lasers with AlN/GaN distributed Bragg reflector
(2008-01-07)
Lu, Tien-Chang
;
Chen, Shih-Wei
;
Lin, Li-Fan
;
Kao, Tsung-Ting
;
Kao, Chih-Chiang
GaN-based two-dimensional (2D) surface-emitting photonic crystal (PC) lasers with AlN/GaN distributed Bragg reflectors are fabricated and demonstrated. The lasing threshold energy density is about 3.5 mJ/cm(2) per pulse under optical pumping at room temperature. Only one dominant emission wavelength of 424.3 nm with a narrow linewidth of 1.1 A above the threshold is observed. The laser emission covers whole circularly 2D PC patterns (50 mu m in diameter) with a small divergence angle. The lasing wavelength emitted from 2D PC lasers with different lattice constants occurs at the calculated band-edges provided by the PC patterns. The characteristics of large area, small divergence angle, and single mode emission from the GaN-based 2D surface-emitting PC lasers should be promising in high power blue-violet emitter applications.
Lasing Characteristics of GaN-based Photonic Crystal Surface-Emitting Lasers
(2009)
Chen, Shih-Wei
;
Kao, Tsung-Ting
;
Liu, Tzu-Wei
;
Lu, Tien-Chang
;
Kuo, Hao-Chung
We successfully demonstrated and analyzed the characteristics of GaN-based photonic-crystal surface emitting lasers at room temperature at different band edges (Gamma, K, and M), showing specific thresholds and polarization angles
Optically pumped GaN-based vertical cavity surface emitting lasers: Technology and characteristics
(2007-08-01)
Wang, Shing-Chung
;
Lu, Tien-Chang
;
Kao, Chih-Chiang
;
Chu, Jong-Tang
;
Huang, Gen-Sheng
We review the fabrication technology and performance characteristics of optically pumped GaN-based vertical cavity surface emitting lasers (VCSELs). Two types of VCSELs with different microcavity structures are described. First type of VCSEL has a hybrid microcavity structure that consists of an epitaxially grown AIN/GaN distributed Bragg reflector (DBR), a GaN active layer with InGaN/GaN multiple quantum wells (MQWs), and a Ta2O5/SiO2 dielectric DBR. Second type of VCSEL has a dielectric DBR microcavity structure that has a similar InGaN/GaN MQWs active layer sandwiched in two dielectric DBRs formed bv Ta2O5/SiO and TiO2/SiO2. Both types of VCSELs achieved laser action under optical pumping at room temperature with emission wavelength of 448 and 414 nm for hybrid DBR VCSEL and dielectric DBR VCSEL, respectively. Both lasers showed narrow emission linewidth with high degree of polarization and large spontaneous emission coupling factors of about 10-2. In addition, a high characteristic temperature of over 240K was measured, and a distinct spatially inhomooeneous emission pattern was observed.
The Characteristics of a High-Q GaN Micro-cavity Light Emitting Diodes
(2007)
Kao, Chih-Chiang
;
Lu, Tien-Chang
;
Kao, Tsung-Ting
;
Lin, Li-Fan
;
Kuo, Hao-Chung
We report the characteristics of a GaN high-Q micro-cavity light-emitting diode (MCLED). The GaN MCLED showed a very narrow linewidth of 0,52 nm at 10 mA and a dominant emission peak wavelength at 465.3 nm. (C)2007 Optical Society of America
The Lasing Action of GaN-based Two-Dimensional Surface-emitting Photonic Crystal Lasers
(2008)
Lu, Tien-Chang
;
Kao, Tsung-Ting
;
Chen, Shih-Wei
;
Kao, Chih-Chiang
;
Lin, Li-Fan
We report fabrication of GaN-based two-dimensional surface emitting photonic-crystal lasers and successful demonstration of lasing action at room temperature with the emission wavelength at 424.3 nm and a low threshold pumping energy density of 3.5 mJ/cm(2). (c) 2008 Optical Society of America