Effects of semiconductor-optical-amplifier nonlinearity on the performance of high-speed intensity-modulation lightwave systems

Saturation and noise properties of quantum-dot optical amplifiers

“…The reason is that the high peak power leads to a momentary depletion of the gain, since the capture process is not able to keep up with the rate of stimulated emission, and a nonequilibrium situation is created, corresponding to dot-barrier hole-burning. However, the presence of gain saturation in this regime of operation will not lead to pattern effects, contrary to the case of bulk and QW SOAs, where operation close to the saturation point commonly leads to strong pattern effects for pulsed signals [37]. The reason for the difference is that in this regime the gain recovers on the timescale of the capture time, i.e., within picoseconds, whereas the gain in bulk and QW SOAs recovers on the timescale of the effective carrier lifetime, i.e., hundreds of picoseconds.…”

Bit Patterning in SOAs: Statistical Characterization Through Multicanonical Monte Carlo Simulations

“…Starting from (1) and (2), the analysis can be conducted in two disparate directions: we can further simplify the model presented in (1) and (2) by applying first-order perturbation, hence deriving small-signal approximations for the received signal [17], [23]- [25]; on the other hand, we can use (1) and (2) to build more elaborate models and study the dynamics numerically [11]. The small-signal model provides insight on the bit patterning mechanism whereas the numerical method provides accuracy.…”

“…In (11) is given by (12) where (13) and . The quantity is a random geometric series [17], [26], whose exact distribution for arbitrary is not known. The bit patterning effect resulting from all the preceding bits is captured in ; if all the preceding bits are zero , and if all are one, .…”

“…Since the analysis is limited to the CW regime, the resulting expressions are useful for BER prediction only when the nonlinear ISI due to bit-patterning is negligible. In a different approach, Saleh and Habbab [17] consider a typical optical link consisting of an ideal On-Off Keying (OOK) transmitter (TX), emitting square pulses for marks, and zero power for spaces, an SOA, an ideal photodetector and an integrate-and-dump or an RC electrical filter. The SOA model includes only saturation and finite carrier lifetime.…”

Optical Demultiplexing Based on Four-Wave Mixing in Semiconductor Optical Amplifiers

“…Because, we assumed a probe pulse repetition rate of 250 Gbit/s, which is much faster than the recovery time of the CD, the CD caused by the probe pulses remains when the following probe pulses are injected into the SOA. Therefore, the pattern effect may arise and deteriorate the DEMUX operation for the multi-bit probe pulses (Saleh & Habbab, 1990). Here, we have considered the pattern effect of the probe bits because the different number of probe pulses is injected between the consecutive pump pulses depends on the bit pattern.…”