Stabilization of self-mode-locked QDash lasers subject to simultaneous continuous-wave optical injection and optical feedback

In this paper, we report stabilization of self-mode-locked two-section quantum-dash lasers on the widest range of delay using simultaneous optical injection and optical feedback. With continuous-wave optical injection, various wavelengths spanning a range from 1568 to 1578 nm were investigated and optimum wavelengths (1571.210 to 1572.710) yielding the narrowest RF linewidth and reduced timing jitter of slave laser were identified. In addition, the dependence of RF linewidth and pulse repetition rate on injected wavelength was further explored. Our results indicate that simultaneous optical feedback and optical injection significantly improves the RF linewidth across the widest delay range compared to optical feedback alone. Under fully resonant feedback and optimum injection parameters, a minimum RF linewidth of 1 kHz (instrument limited) was achieved with simultaneous optical injection plus optical feedback, which was >2× lower than optical feedback alone and more than 100× lower than free-running. This stabilization technique is implemented in an all-optical arrangement without optical/electrical conversion, which is ideal for high-repetition-rate devices and photonic integration.