Browsing by Author "Chen, NK"

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A widely tunable side-polished fiber filter based on dispersive evanescent wave tunneling
(2004)
Chen, NK
;
Chi, S
;
Tseng, SM
;
光電工程學系
;
Department of Photonics
All-fiber optic parametric oscillator based on second order nonlinearity
(2005)
Dyankov, G
;
Chen, NK
;
Chi, S
;
光電工程學系
;
Department of Photonics
An all-fiber parametric oscillator based on (chi)(2) nonlinearity is presented. Nonlinear process takes place in a new type fiber coupler - (chi)(2) grating assisted coupler which consists a part of fiber ring resonator.
An efficient local fundamental-mode cutoff for thermo-optic tunable Er3+-doped fiber ring laser
(2005-09-05)
Chen, NK
;
Chi, S
;
Tseng, SM
;
光電工程學系
;
Department of Photonics
We demonstrate a continuously tunable Er3+-doped fiber laser by incorporating a short-pass filter, which provides a wideband tunable fundamental-mode cutoff with high rejection efficiency (> 45 dB/cm) at long wavelengths, into a ring resonator. The tunable short-pass filter locally suppresses the gain profile of the Er3+-doped fiber at long wavelengths and makes the lasing wavelength continuously move toward short wavelengths when optical polymer is cooling down. The tuning efficiency, tuning range, signal-ASE-ratio, and FWHM linewidth of the laser are 7.65 nm/degrees C, 26 nm (1569.8 similar to 1595.8 nm), 40 dB, and 0.5 nm, respectively.
Comparative study of Schottky diode characteristics in Ni, Ta and Ni/Ta metal contact schemes on n-GaN
(2001-07-01)
Chen, GL
;
Chang, FC
;
Chuang, WC
;
Chung, HM
;
Shen, KC
We have reported current-voltage characteristics of Ta/- and Ni/Ta/n-GaN Schottky diodes under various thermal treatments. Experimental data indicate that the electrical characteristics of Ni/Ta diodes are controlled by the interfacial properties of the Ta and GaN heterointerface for the as-deposited samples and strongly affected by the presence of an oxide layer (Ta2O5) in those high-temperature-annealed diodes. In regard to Ta/Ni diodes, probably because of thermal stability and wide-bandgap properties of tantalum oxide, dramatic improvement in Schottky diode performance was resulted after annealing at high temperatures. The corresponding barrier height and ideality factor values can reach 1.17 cV and 1.09, respectively, even at an annealing temperature of 800 degreesC.
Narrow-band channel-dropping filter based on side-polished fiber with long interaction length
(2004-04-01)
Chen, NK
;
Chi, S
;
Tseng, SM
;
電子工程學系及電子研究所
;
光電工程學系
We demonstrate an all-fiber channel-dropping filter comprising a 2 x 2 side-polished fiber coupler with long coupling length and a narrow-band fiber Bragg grating. The side-polished fibers are fabricated on a silicon wafer acting as a polishing substrate while the alignment V-grooves are simultaneously prepared. Two polished fibers with an intracore Bragg grating between them are combined as a grating-frustrated coupler, and a low-loss channel-dropping filter was achieved with the spectral bandwidth less than 2 nm (25 dB), dropping efficiency greater than 98% and channel isolation greater than 25 dB. The filter can be manufactured through a fast and reliable fabrication process.
Wideband tunable fiber short-pass filter based on side-polished fiber with dispersive polymer overlay
(2004-10-01)
Chen, NK
;
Chi, S
;
Tseng, SM
;
光電工程學系
;
Department of Photonics
It is known that dispersive fiber has an LP01 mode cutoff wavelength that acts as a wavelength filter. With a dispersive polysiloxane polymer overlay on a side-polished single-mode fiber, an in-line tunable fiber short-pass filter with a tuning range of similar to400 nm (1250-1650 nm) and a temperature variation of 15 degreesC was demonstrated. The rejection efficiency was greater than 50 dB, whereas the insertion and polarization-dependent losses were below 0.26 and 0.09 dB, respectively. (C) 2004 Optical Society of America.