Small footprint integrated optical parametric oscillator with a Fabry-Perot resonator

Optical parametric oscillators (OPOs) are key components for applications such as squeezing and random number generation. Their dense integration on-chip would allow the realization of computational networks such as Ising machines. However, the main challenges are related to the OPO footprint, the operation power and the coupling of the single OPOs. Here we present a thin film lithium niobate on insulator double resonant OPO where the nonlinear region is placed in a linear Fabry-Perot cavity formed by two Bragg reflectors, greatly reducing the footprint. Due to the presence of four different ports, the device geometry is suitable for device coupling and integration. The presented OPO generates a signal in the C-band and features a low on-chip threshold of 4 mW, which is lower than the state of the art for double resonant OPOs, and a 30 nm bandwidth, only limited here by reflection band of the mirrors adopted.