Optical noise suppression in epitaxial quantum dot lasers on silicon under mutual injection locking

This paper presents a theoretical investigation into the influence of mutual injection locking on the optical noise characteristics of epitaxial quantum dot (QD) lasers on silicon. The findings reveal that mutual injection locking significantly enhances the output power of QD lasers, achieving up to 3.45 times the output power of their free-running counterparts. Furthermore, the optical noise performance is substantially improved. Specifically, the spectral linewidth undergoes pronounced narrowing even at low coupling ratios, with the linewidth reduced from 3.50 MHz in free-running operation to as low as 13.1 kHz at a coupling ratio of 0.2, effectively mitigating the impact of non-radiative recombination. Additionally, mutual injection locking dramatically improves the relative intensity noise (RIN), achieving a reduction of 14.74 dB/Hz and a minimum RIN of -152.66 dB/Hz. These results highlight mutual injection locking as a practical and efficient strategy for realizing on-chip light sources with narrow linewidths and low-intensity noise, thereby advancing the development of photonic integrated circuits on silicon.