Browsing by Author "Lo, Yen-Hua"

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Compact Photonic Integrated Chip for Tunable Microwave Generation
(2014-03-01)
Chien, Chen-Yu
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Lo, Yen-Hua
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Wu, Yu-Chang
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Hsu, Shun-Chieh
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Tseng, Hung-Ruei
A tunable microwave generation is demonstrated by monolithically integrated photonic chip, which combines a mirror section and two distributed feedback (DFB) lasers. The focus ion beam technology was employed to achieve high-quality air/semiconductor slab for the mirror. Two DFB lasers (named slave and master lasers, respectively) can operate in a single fundamental mode when they are individually pumped. A microwave signal with the differential frequency between the two lasers can be obtained through optical heterodyning. A tunable microwave signal up to 25.5 GHz can be generated by adjusting the injected currents of the two DFB lasers. A four-wave mixing spectrum was measured and the linewidth of the generated radio frequency signal is 1.9 MHz.
Enhanced photocurrent of a nitride-based photodetector with InN dot-like structures
(2014-12-01)
Hsu, Lung-Hsing
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Lin, Chien-Chung
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Han, Hau-Vei
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Lin, Da-Wei
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Lo, Yen-Hua
The InN dot-like layer was applied in the gallium nitride based material for the purpose of infrared photodetectors (PDs). This InN layer was grown by a low-pressure metal organic chemical vapor deposition technology under different growth temperatures. The X-ray diffraction patterns provide the information of crystal structure and the hexagonal orientation was detected. The Raman shifts and photoluminescence were also used to characterize the quality of InN film. Finally, the fabricated Schottky-type photodetector was tested under a solar simulator and a long-wavelength laser (lambda = 1550nm). The measurements show a highly linear relation between photo-generated currents and laser powers for the wavelength of 1550 nm. In the photonic detection range suitable for optical fiber communiation, a quantum efficiency of 9.2% can be observed. (C) 2014 Optical Society of America
Numerical study of a highly efficient solar cell with graded band gap design
(2015-05-01)
Tan, Ming-Hsuan
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Tseng, Hung-Ruei
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Kuo, Chien-Ting
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Hsu, Shun-Chieh
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Lo, Yen-Hua
A linearly graded band gap design in the intrinsic layer of a p-i-n solar cell is studied numerically. An ideal model using Matlab (R) is built and the device performance is calculated using continuity equations and an effective band gap model under various band gap combinations. The power conversion efficiency (PCE) can be as high as 30.21%, while the abrupt junction reference device only exhibits 29.25% under the same parameters. This design is also evaluated using the commercial TCAD software APSYS (R), and the calculations show optimal efficiency enhancements of about 1.14-fold that of the abrupt junction device in an AlAs/GaAs system and 2.05-fold that in an InGaN/GaN system. (C) 2015 The Japan Society of Applied Physics
Numerical Study of Graded Bandgap Solar Cells
(2013)
Tan, Ming-Hsuan
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Tseng, Hung-Ruei
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Lo, Yen-Hua
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Hsu, Shun-Chieh
;
Tsai, Che-Pin
A novel idea of graded band gap design in intrinsic-layer is proposed and studied numerically. We built our device model by using Matlab (R) coding and commercial software APSYS (R). The device performance is calculated by continuity equations, and effective band gap model. The final calculation shows the optimal efficiency enhancement is about 1.32 and 2.18 times of the non-grading band gap device in GaAs and GaN system, respectively.
Tunable microwave generation of a monolithic dual-wavelength distributed feedback laser
(2014-06-02)
Lo, Yen-Hua
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Wu, Yu-Chang
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Hsu, Shun-Chieh
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Hwang, Yi-Chia
;
Chen, Bai-Ci
The dynamic behavior of a monolithic dual-wavelength distributed feedback laser was fully investigated and mapped. The combination of different driving currents for master and slave lasers can generate a wide range of different operational modes, from single mode, period 1 to chaos. Both the optical and microwave spectrum were recorded and analyzed. The detected single mode signal can continuously cover from 15GHz to 50GHz, limited by photodetector bandwidth. The measured optical four-wave-mixing pattern indicates that a 70GHz signal can be generated by this device. By applying rate equation analysis, the important laser parameters can be extracted from the spectrum. The extracted relaxation resonant frequency is found to be 8.96GHz. With the full operational map at hand, the suitable current combination can be applied to the device for proper applications. (C) 2014 Optical Society of America