Lasing Dynamics of Optically-Pumped Ultralow-Threshold Raman Silicon Nanocavity Lasers

A Raman laser based on a high-$Q$ nanocavity in silicon has potential as a light source in photonic integrated circuits, but it is unclear how the significant enhancement of nonlinear optical effects by the cavity affects the lasing dynamics. Spectrally resolved time-domain measurements reveal that free carriers generated by two-photon absorption induce various dynamical effects during the initial lasing process, even at very low threshold power. Surprisingly, the Raman laser signal exhibits large oscillations at high excitation power. This insight will be useful for incorporating such Raman nanocavity lasers into device designs.