Demonstration of an air-slot mode-gap confined photonic crystal slab nanocavity with ultrasmall mode volumes

TL;DR

This paper reports the experimental demonstration of an air-slot mode-gap photonic crystal nanocavity with a high quality factor and ultrasmall mode volume, advancing applications in quantum optics and sensing.

Contribution

It introduces a novel air-slot mode-gap photonic crystal cavity design with record low mode volume and high quality factor, based on a width-modulated line-defect structure.

Findings

Quality factor of 15,000 achieved

Modal volume of 0.02 cubic wavelengths

Mode-gap effect from negative dispersion

Abstract

We demonstrate experimentally an air-slot mode-gap photonic crystal cavity with quality factor of 15,000 and modal volume of 0.02 cubic wavelengths, based on the design of an air-slot in a width-modulated line-defect in a photonic crystal slab. The origin of the high Q air-slot cavity mode is the mode-gap effect from the slotted photonic crystal waveguide mode with negative dispersion. The high Q cavities with ultrasmall mode volume are important for applications such as cavity quantum electrodynamics, nonlinear optics and optical sensing.