High reflection tolerance quantum dots LC-DFB laser for hybrid-silicon photonic integrated circuit

Quantum dot distributed feedback lasers with high optical reflection tolerance are of great significance as the isolator-free light sources for hybrid-silicon photonic integrated circuit. In this work, we experimentally investigate the optical feedback tolerance of our O-band quantum dot lateral coupled distributed feedback lasers, using a fiber-based back reflector. The optical spectra show that the quantum dot distributed feedback laser can maintain stable output power and wavelength under external optical feedback up to -6 dB. Moreover, a high side-mode suppression ratio over 50 dB is also maintained without spectral width broadening, which is significantly different from the broadening observed in the quantum well counterpart. As the optical feedback strength increases to -6 dB, the relative intensity noise of the quantum dot distributed feedback laser remains around -135 dBc/Hz, while the relative intensity noise of commercial quantum well distributed feedback laser increases by 10 dB over the 0 - 20 GHz range. These results indicate the high optical feedback tolerance of our O-band quantum dot lateral coupled distributed feedback lasers laser, making it a promising isolator-free light source solution for the hybrid-silicon photonic integrated circuit.