| Summary: | 碩士 === 國立臺灣大學 === 光電(科學)研究所 === 82 === A numerical model of semiconductor lasers is developed in this
report. It is used to study important characteristics for the
applications in optical transmission systems. Monte Carlo time-
domain simulations are employed to evaluate the noise behaviors
in the model. Mode partition noise (MPN) and timing jitter,
which are strongly related to the noise behaviors, are
discussed in the case of high-speed pulse modulation. The
effects of external reflection on semiconductor lasers have
also been included by adding the time-delayed terms to the
model. When the laser diode is modulated with the pattern of
pesudorandom words in the multi- gigabit-per-second range, the
MPN is enhanced and the dependence on the bias level is weaker.
The MPN can be effectively reduced by increasing the mode
discrimination of laser diodes. Timing jitter is also increased
due to the pattern effect. It can be minimized with an
appropriate choice of the bias level at which the pattern
effect is absent. The feedback-induced noise can enhance the
MPN and timing jitter. The level of feedback should be
sufficiently suppressed to avoid large power penalty or bit-
error-rate (BER) in an optical transmission system. The and
noise behaviors of laser diodes can be closely related to the
modal characteristics. We analyze the mode behaviors of distri-
buted feedback (DFB) lasers at and above threshold by using the
effective-index matrix method. The effect of the axial carrier-
density nonuniformity, i.e., the longitudinal spatial burning
of .lambda./4-shifted DFB lasers operated above threshold can
change the mode discrimination. It can result in the
instability of dynamic single-mode operation in the strongly
coupled case.
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