Browsing by Author "CHI, SE"

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FAULT-LOCATING AND SUPERVISORY TECHNIQUE FOR MULTISTAGED BRANCHED OPTICAL NETWORKS
(1994-07-01)
CHEN, YK
;
CHI, SE
;
光電工程學系
;
Department of Photonics
A fault-locating and supervisory technique for large multistage branched optical fiber networks is proposed. The requirement of ultra-wide dynamic range of an optical time-domain reflectometer (OTDR) to diagnose the network can be tremendously relaxed. Not only can the failure of optical splitter itself be monitored, but also any faults of the fiber links whether before, after, or between optical splitters can be located. The feasibility of this technique was experimentally demonstrated in a 128-branched network using an erbium-doped fiber-amplifier-enhanced OTDR.
OPTIMAL TRANSMISSION CONDITION OF NONLINEAR-OPTICAL PULSES IN SINGLE-MODE FIBERS
(1993-04-01)
LIN, MC
;
CHI, SE
;
光電工程學系
;
Department of Photonics
Optimal transmission conditions of nonlinear optical pulses in single-mode fibers are presented. When an optical pulse propagates in a fiber, it suffers the fiber loss, group velocity dispersion, and self-phase modulation. An optimal output pulse can be obtained by choosing a suitable optical carrier wavelength and an initial input pulse. The system at the optimal condition not only has more stable performance than the dispersion-free system, but also achieves maximum transmission bitrate for a fixed transmission distance. The bit-length product up to 8550 Gb/s.km or more can be achieved by using dispersion-shifted fibers without amplification.
THEORY OF SELF-INDUCED TRANSPARENCY IN A KERR HOST MEDIUM BEYOND THE SLOWLY-VARYING-ENVELOPE APPROXIMATION
(1993-04-01)
CHI, SE
;
WANG, TY
;
WEN, SF
;
電信研究中心
;
光電工程研究所
The self-induced transparency in the Kerr host medium has been studied beyond the slowly-varying-envelope approximation. An analytic solution is obtained. There exists a hyperbolic-secant soliton whose power, pulse width, group velocity, and propagation constant are uniquely determined for given parameters of the medium. The reductions of the group velocities of the solitons by the self-induced-transparency effect in the resonant medium with homogeneous and inhomogeneous broadening are also studied. It is found that there is negative dispersion induced by the self-induced transparency, which is not predicted by the theory with the slowly-varying-envelope approximation. The amount of the induced dispersion is determined by the total dispersion of the system required to be compensated by the Kerr effect. Numerical examples of the self-induced transparency in an erbium-doped fiber are shown. In a typical erbium-doped fiber, the soliton solution has not been found because the inhomogeneous-broadening linewidth of the medium is too large.