Optimum Stabilization of Self-Mode-Locked Quantum Dash Lasers Using Dual Loop Optical Feedback (original) (raw)

We have experimentally investigated the RF linewidth and timing jitter in self-mode-locked two-section quantum dash lasers emitting at ~1.55 µm and operating at ~21 GHz repetition rate, subjected to single and dual loop optical feedback into the gain section, over a wide range of feedback delay. Various feedback conditions are investigated and optimum levels determined for narrowest linewidth and reduced timing jitter for both single and dual-loop configurations. We demonstrate that dual-loop feedback with the shorter feedback cavity tuned to be fully resonant, followed by fine tuning of the phase of the longer feedback cavity, gives stable narrow RF spectra across the widest delay range, 10 – 50× better than single-loop feedback. In addition, for dual-loop configurations, under fully resonant conditions, phase noise is reduced to 295 fs [10 kHz – 100 MHz], the RF linewidth narrows to < 1 kHz, with more than 30 dB fundamental side-mode suppression. We show that dual-loop optical feedback with separate fine tuning of both external cavities is far superior to single-loop feedback, with increased system tolerance against phase delay mismatch, making it a robust and cost-effective technique for developing practical, reliable and low-noise mode-locked lasers, optoelectronic oscillators and pulsed photonic circuits.

Sign up for access to the world's latest research.

checkGet notified about relevant papers

checkSave papers to use in your research

checkJoin the discussion with peers

checkTrack your impact