# Visible nonlinear photonics via high-order-mode dispersion engineering

## TL;DR

This paper demonstrates how dispersion engineering of higher-order waveguide modes enables phase matching of nonlinear processes in the visible and near-visible regimes, leading to new chip-based photonic devices for quantum and classical applications.

## Contribution

It introduces a novel dispersion engineering approach using higher-order modes to achieve anomalous GVD and phase matching in visible regimes, which was previously challenging.

## Key findings

- Demonstrated a near-visible modelocked Kerr frequency comb in silicon nitride microresonators.
- Realized a narrow-band photon-pair source compatible with Rb transitions.
- Extended nonlinear photonics applications into the visible and near-visible spectral ranges.

## Abstract

Over the past decade, remarkable advances have been realized in chip-based nonlinear photonic devices for classical and quantum applications in the near- and mid-infrared regimes. However, few demonstrations have been realized in the visible and near-visible regimes, primarily due to the large normal material group-velocity dispersion (GVD) that makes it challenging to phase match third-order parametric processes. In this paper, we show that exploiting dispersion engineering of higher-order waveguide modes provides waveguide dispersion that allows for small or anomalous GVD in the visible and near-visible regimes and phase matching of four-wave mixing processes. We illustrate the power of this concept by demonstrating in silicon nitride microresonators a near-visible modelocked Kerr frequency comb and a narrow-band photon-pair source compatible with Rb transitions. These realizations extend applications of nonlinear photonics towards the visible and near-visible regimes for applications in time and frequency metrology, spectral calibration, quantum information, and biomedical applications.