Dependence of ultra-low timing jitter on intra-cavity loss for modelocked semiconductor light sources

Summary form only given. The use of stable optical pulse-trains as sampling pulses may allow for accurate analog-to-digital conversion of wide-band RF signals. Specifically, 10 Gbps pulse trains with 10 fs of timing jitter could provide for 12-bit A/D conversion of 10 GHz signals. Modelocked semiconductor lasers may provide the needed sampling pulses for such an application. In determining timing jitter, the phase noise is typically integrated at offset frequencies below 10 MHz. To be useful for such systems, however, characterization of the phase noise up to the roundtrip frequency may be needed. In the paper, comparative measurements of timing jitter (10 Hz to 10 MHz) of a modelocked semiconductor laser under gain and loss modulation is shown. Further, a numerical model incorporating spontaneous emission is developed which points toward low-frequency noise as the main source of jitter. Indications of total timing jitter (10 Hz-5 GHz) of the order of 40 fs is given.