Adaptive quantized feedback equalization of laser FM-response for optical FSK transmission

Using a mathematical model for nonuniform FM-response DFB lasers, the authors calculated the influence of thermal and carrier-density effects on an adaptive quantized feedback equalization circuit (AQFE). A linear networks is introduced which allows the calculation of an equivalent overall system bandwidth. The equalizer circuit is tolerant to dip frequency variations f/sub min/ of the laser's frequency response from 0 to >10 MHz and amplitude variations A between 0.1 and 0.5 for f>>f/sub min/. Hence, lasers can be equalized independent of their individual FM-response. It is calculated that an equivalent bandwidth f/sub c/ of more than 1 GHz can achieved.<
>