Browsing by Author "Chen, Nan-Kuang"

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Analysis of Thermo-Optic Tunable Dispersion-Engineered Short-Wavelength-Pass Tapered-Fiber Filters
(2009-07-01)
Chou, Sen-Yih
;
Hsu, Kuei-Chu
;
Chen, Nan-Kuang
;
Liaw, Shien-Kuei
;
Chih, Yu-Syun
Thermo-optic tunable short-wavelength-pass tapered-fiber filters based on fundamental-mode cutoff mechanism are realized experimentally and analyzed theoretically. The effects of material and waveguide dispersion are investigated and the optimal tapered fiber structures for attaining high-spectral cutoff slope and high-rejection efficiency are determined.
Bandpass Filter With Variable Bandwidth Based on a Tapered Fiber With External Polymer Cladding
(2009-07-01)
Hsu, Kuei-Chu
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Chen, Nan-Kuang
;
Chou, Sen-Yih
;
Liaw, Shien-Kuei
;
Lai, Yinchieh
A thermo-optical bandwidth-variable fiber-based bandpass filter is experimentally and theoretically demonstrated by simply utilizing a tapered standard single-mode fiber covered with a dispersive polymer layer. The 3-dB spectral bandwidth can be tuned from 250 to 500 nm with the filter center wavelength around 1 mu m.
Bandwidth-Variable Bandpass Filter based on Dispersion Engineered Tapered Fiber with External Polymer Cladding
(2009)
Hsu, Kuei-Chu
;
Chen, Nan-Kuang
;
Chou, Sen-Yih
;
Liaw, Shien-Kuei
;
Lai, Yinchieh
A simple thermo-optic bandwidth-variable fiber-based bandpass filter is demonstrated by using a tapered standard single mode fiber covered with a dispersive polymer layer. The 3 dB spectral bandwidth can be tuned from 250 rim with a Gaussian shape to 500 nm with a flat-top shape. (C) 2008 Optical Society of America
CW-pumped evanescent amplification based on side-polished fiber with heavily Er3+-doped glass overlay
(2006-08-01)
Chen, Nan-Kuang
;
Zhang, Liyan
;
Hsu, Kuei-Chu
;
Hu, Lili
;
Chi, Sien
A novel diffractive-pumping scheme is proposed to improve the evanescent amplification using blazed fiber grating for the first time. We also investigate the cw-pumped-evanescent amplification at 1.55 mu m wavelength with the relative optical gain pumped at 1480 nm of around 2 dB based on side-polished fiber with the effective interaction length as long as 16 mm and with a heavily Er3+-doped (N-Er(3+) > 1.19 x 10(21) ions/cm(3)), low refractive index (n(1550) < 1.47) glass overlay, which has no concentration quenching (tau(f) = 9.0 ms).
Double-pass high-gain low-noise EDFA over Sand C+L-bands by tunable fundamental-mode leakage loss
(2007-02-19)
Hung, Chi-Ming
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Chen, Nan-Kuang
;
Lai, Yinchieh
;
Sien, Chi
;
光電工程學系
We demonstrate a high-gain low-noise double-pass tunable EDFA over S- and C+L-bands by discretely introducing fundamental-mode leakage loss in a 16-m-long standard C-band Er3+-doped fiber. The amplified spontaneous emission at the wavelengths of longer than 1530 nm can be substantially attenuated by the ASE suppressing filters to maintain high population inversion and to squeeze out the optical gain for S- band signals. When the filters are disabled, the gain bandwidth immediately returns back to the C+L-bands. Under S-band operation, a 37 dB small signal gain and a minimum 4.84 dB noise figure at 1486.9 nm are achieved with a 980 nm pump power of 154 mW. (c) 2007 Optical Society of America.
Evanescent-field optical amplifiers and lasers
(2006-06-29)
Chen, Nan-Kuang
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Chi, Sien
;
Tseng, Shiao-Min
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Lai, Yinchieh
An optical amplifier and a laser generator based on the fiber side-polished technology, having a high pumping efficiency, a low noise figure and a small footprint are provided in this application. The optical amplifier and the laser, which have a very long effective interaction length in conjunction with highly doped Erbium glass attached to its surface and an addition of a slanted fiber grating inscribed in the guiding core at the polished region can spatially separate the signal and pump power to simultaneously improve the pumping efficiency and optimize the penetrated depth of the signal evanescent-field. The spontaneous emission is kept from being amplified and therefore a high quality amplified signal is produced.
High Er3+ concentration low refractive index fluorophosphate glass for evanescent wave optical amplifiers
(2008-10-01)
Zhang, Liyan
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Chen, Nan-Kuang
;
Hu, Lili
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光電工程學系
;
Department of Photonics
This is about the first reported laser glass with very low no, high Er3+ concentration and no quenching. In this work, a series of high Er3+ concentration (10.6-12.2 x 10(20) ions/cm(3)), low refractive index (n(1550) < 1.47) and relatively high fluorescence lifetime (6.8-12.6 ms) fluorophosphate glasses were made. A cw-pumping evanescent wave optical amplifier experiment was performed with it, and a relative gain of around 2dB at 1550 nm wavelength was achieved while the noise level was almost unchanged. To our knowledge, this is the first successful relative gain in evanescent wave optical amplifiers (EWOA) demonstrated with cw pumping. It is a valuable study of specially designed fluorophosphate glass suitable for EWOA communication experiment. (C) 2008 Elsevier B.V. All rights reserved.
High saturation output power S-band EDFA by suppressing C-band ASE in uniformly inverted EDF
(2007)
Cho, Sheng-Lung
;
Chen, Nan-Kuang
;
Chi, Sien
;
光電工程學系
;
Department of Photonics
We demonstrate an efficient S-band erbium-doped fiber amplifier using C-band ASE suppressing filters discretely in a 13.5-m-long uniformly inverted erbium fiber. The saturation output power and the saturation signal input power can be higher than 6 dBm and -3.6 dBm, respectively under the 980 nm pump power of 198 mW.
High-gain low-noise tunable EDFA over S- and C+L-bands with double-pass configuration
(2007)
Hung, Chi-Ming
;
Chen, Nan-Kuang
;
Lai, Yinchieh
;
Chi, Sien
;
光電工程學系
We demonstrate high-gain low-noise double-pass EDFA over S- and C+L-bands using fundamental-mode cutoff filters in a 16-m-long standard C-band Er(3+)-doped fiber. Under S-band operation, a 37 dB small signal gain and a minimum 4.84 dB noise figure at 1486.9 nm are achieved with a 980-nm pump power of 154 mW.
Highly efficient femtosecond pulse stretching by tailoring cavity dispersion in erbium fiber lasers with an intracavity short-pass edge filter
(2011-08-15)
Chen, Nan-Kuang
;
Liu, Feng-Zhou
;
Chuang, Hsiu-Po
;
Lai, Yinchieh
;
Yang, Shang-Da
We demonstrate highly efficient pulse stretching in Er(3+)-doped femtosecond mode-locked fiber lasers by tailoring cavity dispersion using an intracavity short-pass edge filter. The cavity dispersion is preset at around zero to obtain the shortest pulsewidth. When the cutoff wavelength of the short-pass edge filter is thermo-optically tuned to overlap the constituting spectral components of mode-locked pulses, large negative waveguide dispersion is introduced by the steep cutoff slope and the total cavity dispersion is moved to normal dispersion regime to broaden the pulsewidth. The time-bandwidth product of the mode-locked pulse increases with the decreasing temperature at the optical liquid surrounding the short-pass edge filter. Pulse stretch ratio of 3.53 (623.8fs/176.8fs) can be efficiently achieved under a temperature variation of 4 degrees C. (C) 2011 Optical Society of America
Highly sensitive asymmetric long period fiber grating over 1545 similar to 1650 nm using optical polymer on deep-ablated cladding
(2007)
Chen, Nan-Kuang
;
Hsu, Der-Yi
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Chi, Sien
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光電工程學系
;
Department of Photonics
We demonstrate high temperature-sensitive,wideband-tunable, laser-ablated asymmetric long period fiber gratings with optical polymer overlay. The temperature sensitivity call be as high as 15.8 nm/degrees C over a wide spectral range from 1545 to 1650 nm. (C)2007 Optical Society of America
Influence of a holey cladding structure on spectral characteristics of side-polished endlessly single-mode photonic crystal fibers
(2006-08-01)
Chen, Nan-Kuang
;
Chi, Sien
;
光電工程學系
;
光電工程研究所
;
Department of Photonics
We experimentally investigate the spectral characteristics of side-polished endlessly single-mode photonic crystal fibers of different polishing depths and radii of curvature that are important to mode field diameter. evanescent coupling, waveguide losses, higher-order mode excitation, and dispersion slopes of photonic crystal fiber components. A polished photonic crystal fiber with a greater polishing depth or a larger radius of curvature shows a more dispersive characteristic. In contrast to conventional single-mode fibers, in photonic crystal fibers the evanescent field is more strongly localized, and the propagating light can be more efficiently guided within the deformed core. (c) 2006 Optical Society of America
Influence of a holey cladding structure on spectral characteristics of side-polished endlessly single-mode photonic crystal fibers
(2006-08-01)
Chen, Nan-Kuang
;
Chi, Sien
;
光電工程學系
;
Department of Photonics
We experimentally investigate the spectral characteristics of side-polished endlessly single-mode photonic crystal fibers of different polishing depths and radii of curvature that are important to mode field diameter. evanescent coupling, waveguide losses, higher-order mode excitation, and dispersion slopes of photonic crystal fiber components. A polished photonic crystal fiber with a greater polishing depth or a larger radius of curvature shows a more dispersive characteristic. In contrast to conventional single-mode fibers, in photonic crystal fibers the evanescent field is more strongly localized, and the propagating light can be more efficiently guided within the deformed core. (c) 2006 Optical Society of America
Influence of depressed-index outer ring on evanescent tunneling loss in tapered double-cladding fibers
(2008-08-01)
Chen, Nan-Kuang
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Hsu, Kuei-Chu
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Liaw, Shien-Kuei
;
Lai, Yinchieh
;
Chi, Sien
A tapered fiber with a depressed-index outer ring is fabricated and dispersion engineered to generate a widely tunable (1250-1650 nm) fundamental-mode leakage loss with a high cutoff slope (-1.2 dB/nm) and a high attenuation for stop band (> 50 dB) by modification of both waveguide and material dispersions. The higher cutoff slope is achieved with a larger cross angle between the two refractive index dispersion curves of the tapered fiber and surrounding optical liquids through the use of depressed-index outer ring structures in double-cladding fibers. (c) 2008 Optical Society of America.
Laser-ablated fiber devices and method of manufacturing the same
(2006-11-30)
Chi, Sien
;
Chen, Nan-Kuang
A manufacturing method of a laser-ablated fiber device is proposed. The fiber cladding is removed by laser beam until the evanescent field is accessed. The depth of ablation is controlled by measuring the distance between the interference fringes of the laser. The effective interaction length is tuned by varying the radius of curvature of the fiber. The ablated fibers are mated to act as a fiber coupler. Subsequently, the interaction region is fused or fused-tapered to make a fiber coupler, an add/drop multiplexer, a fiber filter, etc.
Remote-Pumped Integrated Real-Time Monitoring in a WDM-PON
(2008)
Liaw, Shien-Kuei
;
Hong, Kuan-Lun
;
Shei, Yao-Sheng
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Chen, Nan-Kuang
;
Hsu, Kuei-Chu
A proposed configuration to monitor a wavelength division multiplexing (WDM) passive optical network (PON) with high quality in service is presented. This system composes of fiber Bragg gratings, an 1x4 optical switch and an optical time domain reflectometry to diagnose the broken points in real time. The scheme could simultaneously detect multi-optical network units in a WDM-PON. Remote pump integrated residual pumping reused function is implemented. Broken points in different optical paths can be detected simultaneously even the distances to central office are identical. Bit error rate testing is verified with small power penalty, making it an ideal solution for real-time monitoring in a WDM-PON.
Solar-pumped active device
(2006-02-23)
Chi, Sien
;
Chen, Nan-Kuang
;
Shy, Jow-Tsong
The present invention provides a solar-pumped active device which utilizes a holographic antenna grating on a solar energy silicon substrate to select specific diffracted wavelength and couple pump wavelength in an approximately vertical way and converge the pump wavelength to excite an optical gain medium so that an optical amplifier or a laser can be obtained. The present invention requires no big size and is flexible over the surface shape and is suitable for free space optical communications on the ground and satellite optical communications. It means that the holographic antenna grating can be applied on the top floor of a building or on the glass surface of an outer wall. If it is applied to a satellite, the present invention can be deposited on a solar energy cell substrate to form a high optical amplification so that not only the electricity required in satellite optical communications can be reduced, but also a high-speed and large capacity of data can be transferred between satellites.
Solar-pumped active device
(2007-08-16)
Chi, Sien
;
Chen, Nan-Kuang
;
Shy, Jow-Tsong
The present invention provides a solar-pumped active device which utilizes a holographic antenna grating on a solar energy silicon substrate to select specific diffracted wavelength and couple pump wavelength in an approximately vertical way and converge the pump wavelength to excite an optical gain medium so that an optical amplifier or a laser can be obtained. The present invention requires no big size and is flexible over the surface shape and is suitable for free space optical communications on the ground and satellite optical communications. It means that the holographic antenna grating can be applied on the top floor of a building or on the glass surface of an outer wall. If it is applied to a satellite, the present invention can be deposited on a solar energy cell substrate to form a high optical amplification so that not only the electricity required in satellite optical communications can be reduced, but also a high-speed and large capacity of data can be transferred between satellites.
Spectral characteristics of side-polished endlessly single-mode photonic crystal fiber: waveguide dispersion
(2006)
Chen, Nan-Kuang
;
Chi, Sien
;
光電工程學系
;
Department of Photonics
We investigate spectral characteristics of side-polished endlessly single-mode photonic crystal fibers by polishing-depth and radius of curvature, which are important to evanescent coupling, waveguide loss, higher-order modes excitation, and dispersion slopes of photonic crystal fiber components. (C) 2006 Optical Society of America.
Spectral Response of Long Period Fiber Grating based on Tapered Fiber with Side-Contacted Metal Grating
(2008)
Hsu, Kuei-Chu
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Chen, Nan-Kuang
;
Lee, Cheng-Ling
;
Jhuang, Pei-Jhen
;
Chih, Yu-Syun
A simple long-period fiber grating structure using a tapered fiber side-contacted with a metal grating is proposed and demonstrated. The temperature/index tuning sensitivity can be enhanced and the un-usual spectral response of decreasing phase-matching wavelength with respect to increasing temperature has been observed.