Ultrasmall-V high-Q photonic crystal nanobeam microcavities based on slot and hollow-core waveguides.

Photonic crystal nanobeam microcavities based on slot and hollow-core waveguides were proposed and analyzed. Three-dimensional finite-difference time-domain simulations show that both an ultrasmall modal volume (V) and a high quality (Q) factor can be obtained simultaneously in hollow-core-nanobeam mirocavities (HCNMs) due to the strong confinement of fields in the two lateral directions. For a 6.5-μm-long HCNM, the Q factor and V are on the order of 10⁵ and 10⁻²(λ/2n)³, respectively. With compactness, lower fabrication requirements as well as ultrahigh Q/V, the proposed microcavities would be very promising in a variety of applications.