Fig. 2: Second-order spectral phase transition in an OPO.
From: Spectral phase transitions in optical parametric oscillators
a Schematic of the experimental setup, which implements the spectral phase transition in a guided-wave OPO based on PPLN. BS beam splitter, OC output coupler, SPD slow photo-detector, FPD fast photo-detector, SHG second harmonic generation. Spectrum (SP) as a function of detuning obtained through numerical simulation b in anomalous dispersion regime (dotted line represents the theoretically expected spectral splitting, which in the non-degenerate regime is given by: \(\delta \omega \,=\,\sqrt{\frac{{-}2{{\Delta }}\phi }{{\beta }_{2}}}\), d in the normal dispersion regime. Experimental results capturing the second-order critical point c in anomalous dispersion regime, e in normal dispersion regime. It closely follows the square-root behavior (dotted line) in the non-degenerate regime. Color bar represents power spectral density in dB.
