Browsing by Author "Chen, J. H."

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40 GHz Phase Shifter based on Semiconductor Laser
(2008-04-10)
Peng, P. C.
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Wu, F. M.
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Lin, C. T.
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Chen, J. H.
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Kao, W. C.
This investigation experimentally demonstrates a 40 GHz phase shifter based on a semiconductor laser. The phase shift is achieved by adjusting the bias current and wavelength detuning. The device has an optical delay of 23 ps and a phase shift of about 331 degrees.
Broadband C-plus L-band CW wavelength-tunable fiber laser based on hybrid EDFA and SOA
(2013-08-01)
Yeh, C. H.
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Chow, C. W.
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Chen, J. H.
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Chen, K. H.
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Lu, S. S.
In this demonstration, we propose and experimentally investigate a widely C + L band wavelength-tunable fiber ring laser in continuous-wave (CW) tuning based on a hybrid semiconductor optical amplifier (SOA) and erbium-doped fiber amplifier (EDFA) in a serial scheme. When a hybrid first-stage SOA and second-stage EDFA is used inside ring cavity, the effectively amplification range can be extended from C-band to L-band. Here, the proposed laser features wide wavelength-tuning range, high output power, and high side-mode suppression ratio (SMSR). In addition, a tunable range over 91.5 nm (from 1518.5 to 1610.0 nm) has been achieved. (C) 2013 Elsevier Inc. All rights reserved.
Effect of Selenization Processes on CIGS Solar Cell Performance
(2018-07-01)
Wu, C. H.
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Wu, P. W.
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Chen, J. H.
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Kao, J. Y.
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Hsu, C. Y.
Cu(In, Ga)Se-2 (CIGS) films were fabricated by a two-step process method using sputtering from Cu0.7Ga0.3 and In targets. The metallic precursor structures of In/CuGa/In were prepared, and CuGa film was adjusted to the thicknesses of 150, 200, 250 and 300 nm, in order to optimize the CIGS film. After selenization, three independent CIGS (112), CIGS (220/204) and CIGS (312/116) began to crystallize at similar to 280 degrees C and phase peaks continued growing until 560 degrees C. Experimental results showed that with a single stage selenization method, the excessive stoichiometry of the CIGS films was obtained. Using three sequential stages for the selenization process, with a annealing time of 20 min, the stoichiometry of the CIGS absorbers with the Cu/(In + Ga) and Ga/(In + Ga) showed atomic ratios of 0.94 and 0.34, respectively. The intensity of the (112) XRD diffraction peak became stronger, indicating an improvement in the crystallinity. Raman spectra of CIGS absorbers showed a main peak (174 cm(-1)) and two weak signals (212 and 231 cm(-1)). TEM image for electron diffraction pattern showed that the grains were randomly oriented. CIGS solar cell device prepared with a proper selenization, a maximum efficiency of 12.45% was obtained.
Electrically Controlled Phase Shifter using Semiconductor Laser in Optical Single Sideband System
(2009)
Wu, F. M.
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Peng, P. C.
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Yeh, S. K.
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Lin, C. T.
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Chen, J. H.
This investigation experimentally explores a microwave phase shifter using a semiconductor laser in an optical single sidebancl system. The operational bandwidth from 12 to 20 GHz is achieved by adjusting the bias current.
L-Band Multi-Wavelength Fiber Laser Utilizing Reflective Semiconductor Optical Amplifier with a Linear Cavity
(2013)
Yeh, C. H.
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Chow, C. W.
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Lu, S. S.
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Chen, J. H.
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光電工程學系
We first demonstrate an L-band multi-wavelength source only using a C-band reflective semiconductor optical amplifier (RSOA) and a linear cavity formed by a fiber coupler, a polarization controller and a reflected fiber mirror.
Magnetically driven coupling of electronic states in quantum dot molecules
(2006)
Voskobyonikov, O.
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Liu, J. L.
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Chen, J. H.
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
We consider lowest energy states of electrons confined in asymmetrical circular vertically stacked double InAs/GaAs quantum dot molecule. The energies where computed by using the effective three-dimensional one band Hamiltonian, the energy (non-parabolic) and position dependent electronic effective mass approximation, and the Ben Daniel-Duke boundary conditions with the finite hard wall confinement potential. We demonstrated theoretically a possibility to drive dynamically coupled electronic states (relocate electronic wave functions from one dot to another) by applying external magnetic field. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Performance analysis of free space optical communication traffic integrated with passive optical network
(2018-10-18)
Yeh, C. H.
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Chow, C. W.
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Gu, C. S.
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Guo, B. S.
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Cheng, Y. J.
In this Letter, a hybrid 10 Gbit/s on-off keying free space optics and passive optical network (FSO-PON) system is proposed and demonstrated. The experimental received sensitivities are -18 and -20 dBm at the back to back (BtB) and after 25 km fibre transmission, respectively, with 5 m free space traffic link. In the proposed analysis, FSO-PON system can support 32 and 16; and 8 and 4 remote optical wireless units for free space communication at BtB and after 25 km fibre link, respectively, when the free space transmission lengths are 150 and 300 m.
Polarization Switching in 1.3-mu m Quantum Dot Vertical Cavity Surface Emitting Lasers
(2009)
Wu, F. M.
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Lan, R. L.
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Peng, P. C.
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Huang, C. C.
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Peng, R. Y.
This work for the first time, experimentally demonstrates the polarization switching in 1.3 mu m quantum dot VCSEL. The polarization switching in quantum dot VCSEL is achieved by adjusting the optical injection power. (C)2009 Optical Society of America
Simple erbium-doped dual-ring fiber laser configuration for stable and tunable dual-wavelength output
(2011-09-01)
Yeh, C. H.
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Chow, C. W.
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Cheng, B. C.
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Chen, J. H.
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Chen, K. H.
We propose and experimentally investigate a stable and tunable dual-wavelength erbium-doped fiber (EDF) dual-ring laser scheme. Here, two tunable bandpass filters (TBFs) are used inside the dual-ring gain cavity to generate dual-wavelength lasing. And, due to the gain competition of the EDF gain cavity, the mode-spacing (Delta lambda(s)) of lasing dual-wavelength will be limited at different operating wavelengths. Hence, the minimum and maximum mode-spacing in the proposed EDF laser scheme are 0.75 and 15.35 nm in C-band range. Besides, the output performances of proposed fiber laser have also been studied and analyzed.
Single-mode erbium fiber dual-ring laser with 60-nm workable wavelength tunability
(2019-06-01)
Yang, Y. L.
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Yeh, C. H.
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Tsai, C. K.
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Xie, Y. R.
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Lue, C. M.
In this investigation, to reach a widely wavelength-selectable and stable single-longitudinal-mode (SLM) erbium-doped fiber (EDF) ring laser, the unpumped EDF-based saturable absorber (SA) and dual-ring structure are used simultaneously for thickly multi-longitudinal-mode (MLM) suppression. The dual-ring scheme can spread the operation range of gain medium from 1520.0 to 1580.0 nm only by using a C-band erbium-doped fiber amplifier (EDFA). Moreover, the dual-ring scheme and EDF-based SA also could suppress the MLM noise for SLM oscillation. In the tuning range, the Lorentzian 3 dB linewidth is also obtained between 15 and 22 kHz in the wavelength range.
Stable Multiwavelength Semiconductor Laser Using FWM and SBS-Assisted Filter
(2011-11-01)
Yeh, C. H.
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Chow, C. W.
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Wu, Y. F.
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Shih, F. Y.
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Chen, J. H.
A stable and flattened quadruple-wavelength laser system is proposed and experimentally investigated. The laser consists of an external injection Fabry-Perot laser diode (FP-LD) and a stimulated-Brillouin-scattering (SBS)-assisted filter. In the measurement, the power difference (Delta P) of the lasing quadruple-wavelength can be enhanced within 2.0 dB by SBS-assisted filtering after 22-km single-mode fiber (SMF) propagation. In addition, we can change the two injected wavelengths for tuning the quadruple-wavelength. Besides, the output stability of the proposed laser has been studied and analyzed.
Tunable Slow Light in Quantum Well Vertical-Cavity Surface-Emitting Laser at 40 GHz
(2008)
Peng, P. C.
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Wu, F. M.
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Lin, C. T.
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Chen, J. H.
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Shih, P. T.
This investigation experimentally demonstrates tunable slow fight in a quantum well vertical-cavity surface-emitting laser at 40 GHz. Tunable optical delays are achieved by adjusting the bias current and wavelength detuning. (C) 2008 Optical Society of America
Ultra-broadband amplified spontaneous emission source by using heterogeneous optical amplifier
(2012-11-01)
Yeh, C. H.
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Chow, C. W.
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Chen, J. H.
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Lu, S. S.
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光電工程學系
In this work, we propose and experimentally investigate an ultra-broadband amplified spontaneous emission (ASE) light source with 113.8 nm bandwidth (1446.2 to 1560.0 nm) by using a cascaded two-stage optical amplifier, which is consisted of semiconductor optical amplifier (SOA, 1st stage) and erbiumdoped fiber amplifier (EDFA, 2nd stage), when the output intensity is above -35 dBm/0.01 nm. And, the EDFA only uses a 3 m long erbium-doped fiber (EDF) with a 27 mW pumping power and SOA is driven at 200 mA bias current. Moreover, the proposed amplifier also can provide a broadband gain amplification of 114 nm in the wavelengths of 1464.0 and 1578.0 nm with the noise figure distribution of 6.8 to 8.1 dB.
Using optimal cavity loss and saturable-absorber passive filter for stable and tunable dual-wavelength erbium fiber laser in single-longitudinal-mode operation
(2011-09-01)
Yeh, C. H.
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Chow, C. W.
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Wu, Y. F.
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Lin, Y. H.
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Cheng, B. C.
In this investigation, we propose and demonstrate experimentally tunable and stable dual-wavelength erbium doped fiber (EDF) double-ring laser scheme using different coupling losses inside cavity loop for wavelength and mode spacing tuning. Besides, a shorter unpumped EDF is also used to filter the side-modes for lasing wavelength in single-longitudinal-mode (SLM) operation. However, the output mode spacing of dual-wavelength could be limited owing to the homogeneous broadening nature of EDF. As a result, the output performance of the proposed fiber laser have also been analyzed and discussed, such as wavelength tuning range, output power, side-mode suppression ratio (SMSR), stabilities of lasing wavelength and power, relative intensity noise (RIN), etc. (C) 2011 by Astro Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA
Utilizing simple FBG-based erbium-doped fiber architecture for remote temperature sensing
(2015-10-01)
Yeh, C. H.
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Chow, C. W.
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Chen, J. Y.
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Chen, H. Z.
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Chen, J. H.
In this work, we demonstrate experimentally an erbium-doped fiber (EDF) ring laser structure for remote temperature sensing by using fiber Bragg gratings (FBGs) in C-band. Based on the proposed EDF laser configuration, the remote temperature sensing distance is achieved at 50 km. Here, ten FBGs are employed at the remote side for temperature sensing. By tuning the optical tunable filter (TF), the corresponding Bragg wavelength from each FBG can be monitored in the proposed EDF laser. As a result, in the temperature range from 20 to 82 degrees C, the maximum drift of Bragg wavelength can be detected at 0.84 nm.