F. Rönchen, T.F. Langenfeld, and M. Köhl:
🔓 New J. Phys. 21, 123037 (2019)
We report on the realization of a liquid-filled optical microcavity and demonstrate photon-pair generation by spontaneous four-wave mixing. Our source has a spectral brightness of 45 ± 7 mW−2 s−1 MHz−1 and the bandwidth of the emitted photons is ~300 MHz. 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 103 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.