# Compact High-Q Optical Comb based on a Photonic Harmonic Potential

## TL;DR

This paper demonstrates a compact photonic crystal resonator with high Q-factors and equi-spaced resonances, achieved through a harmonic potential, enabling efficient nonlinear interactions in the telecom range.

## Contribution

It introduces a novel harmonic potential in a photonic crystal structure to realize ultra-compact high-Q resonators with multiple equi-spaced modes.

## Key findings

- Q-factors peak at 3 million in statistical analysis
- Resonators exhibit high loaded Q of 0.7 million
- Device made of GaInP suppresses two-photon absorption

## Abstract

An effective harmonic potential for photons is achieved in a photonic crystal structure, owing to the balance of the background dispersion and a bichromatic potential. Consequently, ultra-compact resonators with several equi-spaced resonances and high loaded Q factors (0.7 million) are demonstrated. A detailed statistical analysis is carried out by exploiting the complex reflection spectra measured with Optical Coherent Tomography. The log-normal distribution of the intrinsic Q-factors peaks at 3 million. The device is made of $Ga_{0.5}In_{0.5}P$ in order to suppress the two photon absorption in the Telecom spectral range considered here. This is crucial to turn the strong localization of light into ultra-efficient parametric interactions.