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Now showing 1 - 10 of 167

All optical cross-connect system using erbium-doped fiber-based optical switching unit
(2006-01-01)
Yeh, CH
;
Lee, CC
;
Chi, S
;
光電工程學系
;
Department of Photonics
A novel bidirectional 2x2 optical switch technique, based on the conventional erbium-doped fibers (EDFs) with an operation of pumped or unpumped power level, is proposed and demonstrated experimentally, By using the amplification and absorption function of EDFs and a simply architecture design, the input signals can be switched to a suitable position. The response time of wavelength switching will approach about 2 ms. Moreover, the behavior and system performance of the proposed configuration also have been studied.
A tunable and stabilized single-frequency fiber ring laser based on hybrid amplifier and shorter length EDF with unpumped status
(2006-01-01)
Yeh, CH
;
Fan, KP
;
Chi, S
;
光電工程學系
;
Department of Photonics
A novel fiber ring laser technique, which covers both C- and L-bands, with the function of wavelength tunability and single-longitudinal-mode oscillation, is proposed and demonstrated experimentally. We propose a two-stage hybrid amplifier, which consists of a semiconductor optical amplifier (SOA) and an erbium-doped fiber amplifier (EDFA) with cascade configuration, for the gain profile to achieve C- to L-band (1540 to 1610 nm). A saturated-absorber-based autotracking filter, which composes of an unpumped erbium-doped fiber (EDF) and an optical reflected mirror (ORM), is employed to provide fine mode restriction and guarantee the single-frequency operation. The unpumped EDF must use shorter length to retrieve the stabilized single-frequency operation while the EDF length is between 0.5 to 1 in long. The effectively operation range is from 1542 to 1618 nm. The maximal output power of 5.7 dBm is retrieved at near 1577 nm, and the output power will drop to 3.7 and -0.32 dBm at 1604 and 1616 rim, respectively. The SMSR can be up to 53.2 dB/0.05 nm at around 1577 nm. The performance of output power of > 2.1 dBm, power stability of <= 0.02 dB, wavelength variation of < 0.01 nm and side-mode suppression ratio (SMSR) of > 31 dB/0.05 nm has been demonstrated for this single-frequency fiber laser over the wavelength range of 1550 to 1608 nm. The linewidth (RF) spectrum of the proposed structure has also been studied.
Stabilized single-frequency fiber ring laser based on hybrid amplifier and fiber Fabry-Perot devices for C- plus L-band operation
(2005-10-01)
Yeh, CH
;
Cheng, BC
;
Chen, CY
;
Chi, S
;
光電工程學系
Using optical Fabry-Perot devices for a wavelength-tunable S-band erbium-doped fiber ring laser with single-frequency operation
(2005-10-01)
Yeh, CH
;
Chien, HC
;
Cheng, BC
;
Lee, CC
;
Chi, S
We have proposed and experimentally demonstrated a stabilized and tunable S-band erbium-doped fiber ring laser by using a Fabry-Perot laser diode (FPLD) and a fiber Fabry-Perot filter inside the ring cavity. Due to the bandwidth limitation of the FPLD, the effective operating range of the proposed laser is confined to 1490.28 to 1521.22 nm with a tuning step of 0.08 nm. A side-mode suppression ratio of > 39.1 dB at 0.05 nm and an output power of > 0.4 dBm can be achieved while this laser is tuned from 1490.28 to 1510.27 nm. Zero output wavelength variation and output power fluctuation <= 0.03 dB have also been obtained. (c) 2005 Society of Photo-Optical Instrumentation Engineers.
Broadband C- plus L-band double-ring fiber baser based on a two-stage hybrid amplifier
(2005-10-01)
Yeh, CH
;
Cheng, BC
;
Chen, CY
;
Chi, S
;
光電工程學系
A stable and wavelength-tunable C- plus L-band fiber double-ring laser, which uses a two-stage hybrid amplifier with a semiconductor optical amplifier and an erbium-cloped fiber amplifier, has been proposed and experimentally demonstrated. Based on the double-ring configuration, the proposed fiber ring laser exhibits more stable output wavelengths and powers than the single-ring laser. A wide tunable range of 1540 to 1620 nm, a side-mode suppression ratio (SMSR) of > 31.2 dB/0.05 nm over a wide tuning range from 1550 to 1612 nm, and an output power of > 2 dBm over the operation range of 1546 to 1608 nm have been achieved. (c) 2005 Society of Photo-Optical Instrumentation Engineers.
Coexistence of a self-induced transparency soliton and a Bragg soliton
(2002-11-01)
Tseng, HY
;
Chi, S
;
光電工程研究所
;
Institute of EO Enginerring
We theoretically show that a self-induced transparency (SIT) soliton and a Bragg soliton can coexist in a nonlinear photonic band gap (PBG) medium doped uniformly with inhomogeneous-broadening two-level atoms. The Maxwell-Bloch equations for the pulse propagating through such a uniformly doped PBG structure are derived first and further reduced to an effective nonlinear Schrodinger equation. This model describes an equivalent physical mechanism for a Bragg-soliton propagation resulting from the effective quadratic dispersion balancing with the effective third-order nonlinearity. Because the resonant atoms are taken into account, the original band gap can be shifted both by the dopants and the instantaneous nonlinearity response originating from an intense optical pulse. As a result, even if a SIT soliton with its central frequency deep inside the original forbidden band, it still can propagate through the resonant PBG medium as long as this SIT soliton satisfies the effective Bragg-soliton propagation. An approximate soliton solution describing such coexistence is found. We also show that the pulse width and group velocity of this soliton solution can be uniquely determined for given material parameters, atomic transition frequency, and input central frequency of the soliton. The numerical examples of the SIT soliton in a one-dimensional As2S3-based PBG structure doped uniformly with Lorentzian line-shape resonant atoms are shown. It is found that a SIT soliton with similar to100-ps width in such a resonant PBG structure can travel with the velocity being two orders of magnitude slower than the light speed in an unprocessed host medium.
Self-induced transparency with transverse variations in resonant media by the power series approximation method
(2005-01-01)
Cheng, BC
;
Tseng, HY
;
Chi, S
;
光電工程研究所
;
Institute of EO Enginerring
This paper presents the analytic solutions of self-induced transparency with transverse variations in resonant media by a self-consistent power series approximation method. We solve the Maxwell-Bloch equations by retaining all integral terms from the inhomogeneous broadening and the second-derivative terms with respect to distance and time. The lowest-order approximation is presented in detail. We discuss the characteristics of the distortionless pulses that propagate in an inhomogeneously broadening medium. It is shown that the group velocity and peak power of the self-induced transparency solitons could be represented in terms of the pulse width, the angle between phase velocity and group velocity, and the basic material parameters of the resonant medium. The chirping of the soliton is also discussed.
Large phase shift of nonlocal optical spatial solitons
(2004-01-01)
Guo, Q
;
Luo, B
;
Yi, FH
;
Chi, S
;
Xie, YQ
In this paper, we discuss the evolution of the optical beam in nonlocal cubic nonlinear media, modeled by the nonlocal nonlinear Schrodinger equation (NNLSE). A different approximate model to the NNLSE is presented for the strongly nonlocal media with arbitrary response functions. An exact analytical solution of the model is obtained, and a spatial soliton is found to exist. A different phenomenon is revealed that the phase shift of such a nonlocal optical spatial soliton can be very large comparable to its local counterpart. The stability of the solution is rigorously proved. The comparisons of our analytical solution with the numerical simulation of the NNLSE, as well as with Snyder-Mitchell (linear) model [A. W. Snyder and D. J. Mitchell, Science 276, 1538 (1997)] are given.
Improving soliton transmission in a dispersion compensated system by pre-chirping and pre-shaping method
(1998-03-01)
Chi, S
;
Lin, SC
;
Dung, JC
;
光電工程學系
;
Department of Photonics
Soliton transmission in a dispersion compensated system is numerically studied. The numerical results are consistent with the previous experimental results. The pre-chirping and pre-shaping method is used to reduce the timing jitter and the dispersive wave in a dispersion compensated soliton transmission system. We have found that the pre-chirping and pre-shaping method can stabilize the variation of pulse shape due to the perturbation of the dispersion compensation fiber and the timing jitter can be greatly reduced. (C) 1998 Elsevier Science B.V.
Gain flattening of erbium-doped fibre amplifier using fibre Bragg gratings
(1998-03-19)
Dung, JC
;
Chi, S
;
Wen, SF
;
光電工程學系
;
Department of Photonics
A new technique, using fibre-Bragg gratings with different centre frequencies to reflect the different channel signals at different positions, is proposed for flattening the gain spectrum of an erbium-doped fibre amplifier. A designed gain excursion of <0.1dB can be achieved for 16 channel multiplexed signals with 0.1mW input power in the 1532-1562nm wavelength region.

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🏛️國立陽明交通大學機構典藏

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