Highly efficient and widely tunable Si3N4 waveguide-based optical parametric oscillator

We demonstrate an efficient and widely tunable synchronously pumped optical parametric oscillator (OPO) exploiting four -wave mixing (FWM) in a silicon nitride (Si3N4) waveguide with inverted tapers. At a pump pulse duration of 2 ps, the waveguide-based OPO (WOPO) exhibited a high external pump -to -idler conversion efficiency of up to -7.64 dB at 74% pump depletion and a generation of up to 387 pJ output idler pulse energy around 1.13 mu m wavelength. Additionally, the parametric oscillation resulted in a 64 dB amplification of idler power spectral density in comparison to spontaneous FWM, allowing for a wide idler wavelength tunability of 191 nm around 1.15 mu m. Our WOPO represents a significant improvement of conversion efficiency as well as output energy among chi 3 WOPOs, rendering an important step towards a highly efficient and widely tunable chip -based light source for, e.g., coherent anti -Stokes Raman scattering.