# Correlated photon-pair generation in a liquid-filled microcavity

## TL;DR

This paper demonstrates photon-pair generation in a liquid-filled microcavity with tunable wavelength, significantly enhancing pair correlation rate and quality compared to previous setups.

## Contribution

It introduces a liquid-filled microcavity for efficient photon-pair generation with tunable emission and improved correlation metrics.

## Key findings

- Photon pairs generated with ~300 MHz bandwidth.
- Tunable emission wavelength between 770 and 800 nm.
- Over 1000-fold increase in pair correlation rate per unit pump power.

## Abstract

We report on the realization of a liquid-filled optical microcavity and demonstrate photon-pair generation by spontaneous four-wave mixing. The bandwidth of the emitted photons is $\sim 300$ MHz and we demonstrate tuning of the emission wavelength between 770 and 800 nm. Moreover, by employing a liquid as the nonlinear optical medium completely filling the microcavity, we observe more than a factor $10^3$ increase of the pair correlation rate per unit pump power and a factor of 1.7 improvement in the coincidence/accidental ratio as compared to our previous measurements.