UV, visible, and near-infrared light generation through cascaded nonlinear processes in silicon-nitride microring resonators pumped at telecom wavelength

On-chip coherent light generation has wide-ranging applications in metrology, spectroscopy, quantum optics, etc. In this study, we demonstrate the generation of coherent light from a silicon-nitride microring resonator using cascaded nonlinear processes. This involves a telecom pump laser and its efficiently generated second harmonic through the coherent photogalvanic effect. By leveraging second- and third-order nonlinear effects such as harmonic generation, (stimulated) four-wave mixing, and optical parametric oscillation, we achieve the generation of UV, visible, and near-infrared light. This study highlights the potential of silicon nitride integrated photonics in producing broad-spectrum light sources at wavelengths beyond the capabilities of conventional lasers.