Low Timing-Jitter Semiconductor Mode-locked Laser as Fast Sampler in Analog to Digital Converter

The ever-growing demand for higher computing bandwidth in both military and civilian applications has pushed signal speed into the tens of GHz frequency range, thus requiring fast optical digitizers. WaveBand Corporation proposes to develop a new lowtiming-jitter monolithic semiconductor mode-locked laser. The specially designed two-section laser will serve as a stable clock in a high-speed sampler for optical analog-to-digital (A/D) converters. It will be hybridly mode-locked. A saturable absorberwill generate short pulses and an external oscillator (modulating the laser with microwave signal close to its cavity repetition rate) will improve its timing performance. Moreover, the pulse-to-pulse repetition time between neighboring pulses will becorrelated to provide stability over long time periods. In Phase I of this project we analyzed the statistics of timing jitter and demonstrated sub femtosecond pulse-to-pulse rms timing jitter in actively mode-locked semiconductor laser. Phase II willresult in the demonstration of a complete stable optical sampler based on the proposed hybridly mode-locked semiconductor laser.