Four-wave mixing in 1.3 μm epitaxial quantum dot lasers directly grown on silicon

This work compares the four-wave mixing (FWM) effect in epitaxial quantum dot (QD) lasers grown on silicon with quantum well (QW) lasers. A comparison of theory and experiment results shows that the measured FWM coefficient is in good agreement with theoretical predictions. The gain in signal power is higher for p-doped QD lasers than for undoped lasers, despite the same FWM coefficient. Owing to the near-zero linewidth enhancement factor, QD lasers exhibit FWM coefficients and conversion efficiency that are more than one order of magnitude higher than those of QW lasers. Thus, this leads to self-mode locking in QD lasers. These findings are useful for developing on-chip sources for photonic integrated circuits on silicon.