Fig. 3: Saturable absorber response and laser simulation.
From: Silicon photonics-based high-energy passively Q-switched laser
a, An ideal reflectivity (R) curve of the NLI-SA as a function of the power-dependent differential phase shift. The green and red arrows indicate the pulsed operation region (positive slope) and CW operation region (negative slope), respectively. b, The NLI-SA reflectivity curve of an ideal (I), fabricated (F) device and the case where the curve is tuned for Q-switching (Q). c, A measurement of the thermally tuned NLI-SA reflectivity to help extract the NLI-SA reflectivity curve. The error bars represent the reflectivity variations around the mean for five measurements owing to fluctuations in signal coupling and thermal drift of the chip due to heating. The inset shows a cartoon of how the NLI-SA reflectivity as a function of Ф(p) shifts with temperature applied by thermal phase shifters, which helps to trace the as-fabricated reflectivity of the NLI-SA (dashed curve in b). d, The simulated laser dynamics in terms of the cavity round-trip loss, the gain and the output power normalized to its maximum over several periods. Inset, close-up of the dynamics over one pulse.
