Ultra-high-Q photonic double-heterostructure nanocavity

Abstract

High-quality factor (Q) photonic nanocavities that strongly confine photons in volumes of optical-wavelength dimension are attracting much attention in various fields, including photonics1,2,3,4,5, telecommunications6,7, quantum information8 and cavity quantum electrodynamics9,10, because a strong light–matter interaction is obtained. An important design rule has been proposed11 in an attempt to realize high-Q nanocavities in two-dimensional photonic-crystal slabs. The form of the cavity electric-field distribution should slowly vary, most ideally as described by a gaussian function, in order to suppress out-of-slab photon leakage. However, the exact cavity structure that minimizes photon leakage has not yet been established. Here, we demonstrate the importance of the formation of a photonic double-heterostructure, which has resulted in the realization of nanocavities with extremely high-Q factors of 600,000, more than one order of magnitude higher than any previous reports11,12,13,14. We have also shown theoretically that Q-factors greater than 20,000,000 may be obtained when optimizing the structure.