Purcell-enhanced microcavity Raman scattering from pressurized gases

We have investigated the Purcell enhancement of spontaneous Raman scattering in microcavities with a test gas under pressure. Micromirrors were fabricated on bulk substrates and assembled into sealed microcavity arrays into which gases could be introduced at pressures of up to 35 bar. We focused on the ν1 Q-branch Raman band in carbon dioxide (1388.2 cm−1) and measured the rate of Raman scattered photons as a function of pressure and concentration. The rate was found to increase approximately linearly with pressure with no significant broadening of the lineshape associated with the doubly resonant Purcell-enhanced Raman process. This lack of broadening is a unique feature of the microcavity-based scheme in which mirrors are only separated by a few microns, making pressurization an effective method to lower the limit of detection.