Optical-fiber-based measurement of an ultrasmall volume high-Q photonic crystal microcavity

A two-dimensional photonic crystal semiconductor microcavity with a quality factor Q∼40,000 and a modal volume V_eff∼0.9 cubic wavelengths is demonstrated. A micron-scale optical fiber taper is used as a means to probe both the spectral and spatial properties of the cavity modes, allowing not only measurement of modal loss, but also the ability to ascertain the in-plane localization of the cavity modes. This simultaneous demonstration of high-Q and ultrasmall V_eff in an optical microcavity is of potential interest in nonlinear optics, optoelectronics, and quantum optics, where the measured Q and V_eff values could enable strong coupling to both atomic and quantum dot systems.