Lithographically Fabricated Optical Cavities for Refractive Index Sensing

Since the development of distributed Bragg gratings, high resolution lithography and etching have been applied towards the concentration of light. The most important application of lithographically fabricated microcavities has been for the spectral control over laser emission. Here we describe the opportunities that arise from further miniaturization of laser cavities by using high index contrast photonic crystal mirrors and annular Bragg reflectors. We have used these optical cavities, with mode volumes as small as 10^–17 l, to perform spectroscopic analysis and compare the mode volumes and sensitivities of these geometries.