Modelling Defect Cavities Formed in Inverse Three-Dimensional Rod-Connected Diamond Photonic Crystals

TL;DR

This paper models defect cavities in inverse rod-connected diamond photonic crystals, demonstrating how to optimize their structure for high Q-factors and minimal mode volumes to enhance light trapping and nonlinear effects.

Contribution

It introduces a detailed analysis of defect cavities in inverse RCD photonic crystals, including optimization strategies for achieving record-low mode volumes.

Findings

Wide photonic band gaps achieved through dimension optimization.

High Q-factors and mode volumes < 0.06 cubic wavelengths in symmetric defect arrangements.

Record low mode volume for high index cavities.

Abstract

Defect cavities in 3D photonic crystal can trap and store light in the smallest volumes allowable in dielectric materials, enhancing non-linearities and cavity QED effects. Here, we study inverse rod-connected diamond (RCD) crystals containing point defect cavities using plane-wave expansion and finite-difference time domain methods. By optimizing the dimensions of the crystal, wide photonic band gaps are obtained. Mid-bandgap resonances can then be engineered by introducing point defects in the crystal. We investigate a variety of single spherical defects at different locations in the unit cell focusing on high-refractive-index contrast (3.3:1) inverse RCD structures; quality factors (Q-factors) and mode volumes of the resonant cavity modes are calculated. By choosing a symmetric arrangement, consisting of a single sphere defect located at the center of a tetrahedral arrangement, mode volumes < 0.06 cubic wavelengths are obtained, a record for high index cavities.