Regime where zero-bias is the low-power solution for digitally modulated laser diodes

We demonstrate that when a laser diode is digitally modulated with zero-bias, the average electrical power consumption can be less than a threshold-biased scheme for the same bit error rate. We find that the power consumption of large threshold >10 mA lasers with zero-bias is comparable to or less than with threshold-bias modulation as long as B/spl tau/<1/ln(2), where B and /spl tau/ are the bit rate and the laser´s carrier lifetime, respectively. Experiments with a buried crescent laser diode confirm this claim at both 300 K and 77 K. The power penalty of zero-bias at higher bit rates is also discussed.