Spectral channels increase of multi-wavelength visible laser enabled by SHG-SFG hybrid processes

Spectral evolution in nonlinear optical processes, such as second harmonic generation (SHG) and sum frequency generation (SFG), plays a crucial role in multi-wavelength generation through nonlinear frequency conversion. In this study, the enhancement of spectral performance in a multi-wavelength visible laser facilitated by SHG-SFG hybrid processes is proposed and demonstrated, for the first time to our knowledge. An output of up to eleven wavelengths can be achieved using a six-wavelength pump. Theoretical analysis suggests that the increase in spectral channel count is attributed to the SHG-SFG hybrid processes. Additionally, each nonlinear process operates independently without competition under small-signal approximation, validated through temperature variations. This research not only elucidates the mechanism of spectral evolution in hybrid nonlinear processes but also presents a viable method for improving the spectral performance of a multi-wavelength visible light source.