Browsing by Author "Lai, Fang-I."

Now showing 1 - 4 of 4

Characteristics of single-mode InGaAs sub-monolayer quantum-dot photonic-crystal VCSELs emitting in the 990 nm range
(2008)
Yang, Hung-Pin D.
;
Hsu, I. -Chen
;
Lai, Fang-I.
;
Lin, Gray
;
Hsiao, Ru-Shang
We have made InGaAs sub-monolayer (SML) quantum dot photonic crystal vertical-cavity surface-emitting lasers (QD PhC-VCSELs) for fiber-optic applications. The active region of the device contains three InGaAs SML QD layers. Each of the InGaAs SML QD layer is formed by alternate deposition of InAs (< 1 ML) and GaAs. Single fundamental mode CW output power of 3.8 mW at 28 mA has been achieved in the 990 nm range, with a threshold current of 0.9 mA. Side-mode suppression ratio (SMSR) larger than 35 dB has been demonstrated over the entire current operation range. Near-field images of the PhC-VCSELs were also measured and studied.
Extraction Efficiency Enhancement of GaN-Based Light-Emitting Diodes by Microhole Array and Roughened Surface Oxide
(2009-05-01)
Lai, Fang-I.
;
Ling, S. C.
;
Hsieh, C. E.
;
Hsueh, T. H.
;
Kuo, Hao-Chung
The light-output power of GaN-based light-emitting diodes (LEDs) was enhanced by microhole array pattern and roughened GaO(x) film grown on the exposed surface. The GaO(x) film was grown by photoelectrochemical (PEC) oxidation via H(2)O and formed a naturally rough oxide surface and GaO(x)/GaN interface. Compared with that of conventional broad-area LEDs, the output power of the microhole array LED and the surface-oxidized microhole array LED increased by 1.38 and 1.82 times at 20-mA forward current, respectively. The results show that the microhole array pattern with the roughened surface oxide method could significantly enhance light extraction efficiency and be a candidate for manufacturing high-efficient low-cost GaN-based LEDs.
High-power single-mode submonolayer quantum-dot photonic crystal vertical-cavity surface-emitting lasers
(2007-09-01)
Lai, Fang-I.
;
Yang, H. P. D.
;
Lin, G.
;
Hsu, I. -Chen
;
Liu, Jui-Nung
A high-power, wide operation-range single-fundamental-mode InGaAs submonolayer (SML) quantum dot (QD) photonic crystal vertical-cavity surface-emitting laser (VCSEL) for fiber-optic applications was demonstrated. Single-fundamental-mode with a threshold current (I-th) of 0.9 mA and maximum continue-wave (CW) output power of 3.8 mW at 28 mA has been achieved in the 990 nm range. A side-mode suppression ratio (SMSR) larger than 35 dB has been observed over the entire current operating range. The far field measurement shows that the beam divergence angle remains very small and almost unchanged between 6.7-6.9 degrees, with the operation range increasing from 3 to 20 mA.
Photonic-crystal light-emitting diodes on p-type GaAs substrates for optical communications
(2008)
Yang, Hung-Pin D.
;
Liu, Jui-Nung
;
Lai, Fang-I.
;
Kuo, Hao-Chung
;
Chi, Jim Y.
Oxide-confined photonic-crystal (PhC) light-emitting diodes (LEDs) on p-type GaAs substrate in the 830 nm range are reported. The device consists of a bottom distributed Bragg reflector (DBR), quantum wells (QWs), and a top DBR, with a photonic-crystal structure formed within the n-type ohmic contact ring for light extraction. The etching depth of the PhC holes is 17-pair out of the 22-pair top DBR being etched off. The internally reflected spontaneous light emission can be extracted out of PhC holes because of lower reflectance within those areas. High-resolution micrographic imaging studies indicate that the device emits light mainly through the photonic-crystal holes and it is suitable for optical communications.