DEPENDENCE OF TIMING JITTER ON BIAS LEVEL FOR SINGLE-MODE SEMICONDUCTOR-LASERS UNDER HIGH-SPEED OPERATION

The dependence on the bias level of some quantities characterizing optical pulse statistics, such as the turn-on time, pulsewidth, maximum output photon number, and average output power, of single-mode semiconductor lasers are numerically analyzed at frequencies in the GHz range. Periodic modulation and pseudorandom word modulation are considered. In the former regime timing jitter is shown to be rather independent of the bias current. In the latter regime timing jitter becomes larger when biasing above threshold than when biasing below threshold. This large jitter is found to be associated with a bimodal probability distribution of the turn-on time, which yields undesirable pattern effects. A privileged bias, slightly below threshold, suppresses these pattern effects making the laser response almost independent of previous input bits. For such bias value the probability distribution functions of the turn-on time in the case of the periodic and pseudorandom word modulation coincide.