Ultrahigh-stability photonic sampling streams from an actively-modelocked semiconductor diode ring laser

Summary form only given. Future analog-to-digital conversion needs have inspired recent focus on hybrid optoelectronic systems. The use of short optical pulses for sampling temporal signals promises more accuracy than high-speed electronic comparators. Additional requirements for achieving high precision in high-speed sampling streams are ultralow amplitude and phase noise. Semiconductor optical amplifiers (SOAs) have exhibited proficiency in each of these areas. We report the experimental achievement of optical sampling streams capable of resolving 8.6 bits at a 10 GHz repetition rate. Such accuracy results from ultrashort pulsewidths (1.2 ps), ultralow amplitude noise (0.12% RMS), and ultralow residual jitter (43 fs RMS). A phaselocked-loop (PLL) tested at 2 GHz has further reduced jitter by 91% (from 88 fs to 8 fs).