Fig. 3: Characterization of the second-order critical point.
From: Spectral phase transitions in optical parametric oscillators
OPO average output power as a function of cavity detuning obtained numerically (a) and experimentally (b) using a slow detector. This demonstrates the maximum conversion efficiency at the critical point. c Continuous order parameter but discontinuous derivative typical of a second-order phase transition. The inset shows the gain curve as a function of cavity detuning, which has its maximum at the critical point. d Spontaneous emergence of beat-note around the critical point. Measured RF spectrum (SP) captured using a fast detector in a multi-heterodyne measurement showing co-existence of the signal and idler combs in the non-degenerate regime and their offset tuning.
