Cylindrical vector resonant modes achieved in planar photonic crystal cavities with enlarged air-holes

TL;DR

This paper demonstrates how enlarging the central air-hole in a triangular-lattice planar photonic crystal creates high-Q cylindrical vector resonant modes with symmetric field distributions and beam profiles, useful for advanced photonic applications.

Contribution

It introduces a simple method to generate cylindrical vector resonant modes in planar photonic crystals by enlarging the central air-hole, achieving high quality factors and symmetric beam profiles.

Findings

High-Q cylindrical vector resonant modes with Q around 3,000.

Modes exhibit high-quality cylindrical vector beam profiles.

Optimization possible by modifying neighboring air-holes.

Abstract

We reveal a triangular-lattice planar photonic crystal supports Bloch modes with radially and azimuthally symmetric electric field distributions at the top band-edge of the first photonic band. Bifurcated from the corresponding Bloch modes, two cylindrical vector resonant modes are achieved by simply enlarging the central air-hole of the planar photonic crystal, which have high quality factors around 3,000 and small mode volume. The far-field radiations of the two resonant modes present high-quality cylindrical vector beam profiles. The resonant modes could be optimized by modifying the six nearest neighboring air-holes around the central defect. The cylindrically symmetric characteristics of the resonant mode's near- and far-fields might provide a new view to investigate light-matter interactions and device developments in planar photonic crystal cavities.