Fig. 3: The SFG waveguide output spectra and conversion efficiencies.

a the spectrum of reference light (dashed red), probe light without SFG (solid red), probe light with SFG (magenta), and SFG light (blue). The SFG spectrum (0.01 nm resolution) consists of a c-SFG peak and broadband i-SFG background. The absolute level of the SFG spectrum is not shown. b the theoretically predicted (curve) and experimentally measured (errorbar or dot) c-SFG efficiency (red) and total SFG efficiency (blue). The SFG efficiency of the single-frequency probe and reference light is also plotted (green dot and curve) as a baseline. The error bars are obtained by taking the standard deviation of three repeated measurements.