Hyperparametric oscillation via bound states in the continuum

TL;DR

This paper demonstrates that using Friedrich-Wintgen bound states in the continuum (BICs) in microresonators significantly improves the efficiency and power of on-chip optical hyperparametric oscillation, overcoming previous limitations.

Contribution

The study introduces the use of BICs to enhance on-chip hyperparametric oscillation efficiency and power, addressing parasitic mode competition and cavity Q ratio limitations.

Findings

Achieved unprecedented conversion efficiency in hyperparametric oscillation

Generated high-power, continuous-wave electromagnetic radiation in Kerr media

Enhanced understanding of microresonator-waveguide systems

Abstract

Optical hyperparametric oscillation based on the third-order nonlinearity is one of the most significant mechanisms to generate coherent electromagnetic radiation and produce quantum states of light. Advances in dispersion-engineered high-$Q$ microresonators allow for generating signal waves far from the pump and decrease the oscillation power threshold to submilliwatt levels. However, the pump-to-signal conversion efficiency and absolute signal power are low, fundamentally limited by parasitic mode competition and attainable cavity intrinsic $Q$ to coupling $Q$ ratio, i.e., $Q_{\rm i}/Q_{\rm c}$. Here, we use Friedrich-Wintgen bound states in the continuum (BICs) to overcome the physical challenges in an integrated microresonator-waveguide system. As a result, on-chip coherent hyperparametric oscillation is generated in BICs with unprecedented conversion efficiency and absolute signal power. This work not only opens a path to generate high-power and efficient continuous-wave electromagnetic radiation in Kerr nonlinear media but also enhances the understanding of microresonator-waveguide system - an elementary unit of modern photonics.