Efficient and accurate analysis of photon density of states for two-dimensional photonic crystals with omnidirectional light propagation

TL;DR

This paper presents an efficient and accurate method for analyzing the photon density of states in 2D photonic crystals, accounting for both radiative and evanescent modes to better understand omnidirectional light propagation.

Contribution

The authors extend finite element analysis with waveguiding theory to accurately compute omnidirectional PDOS in 2D PCs, including evanescent modes, offering a faster alternative to 3D band structure calculations.

Findings

Complete band gaps are closed when evanescent modes are included.

The method accurately calculates in-plane dispersion relations for TE and TM modes.

The approach is relevant for spontaneous emission and dipole radiation in 2D structures.

Abstract

Omnidirectional light propagation in two-dimensional (2D) photonic crystals (PCs) has been investigated by extending the formerly developed 2D finite element analysis (FEA) of in-plane light propagation in which the corresponding band structure (BS) and photon density of states (PDOS) of 2D PCs with complex geometry configurations had been calculated more accurately by using an adaptive FEA in real space for both the transverse electric (TE) and transverse magnetic (TM) modes. In this work, by adopting a waveguiding theory under the consideration of translational symmetry, the omnidirectional PDOS corresponding to both the radiative and evanescent waves can be calculated accurately and efficiently based on the in-plane dispersion relations of both TE and TM modes within the irreducible Brillouin zone. We demonstrate that the complete band gaps shown by previous work considering only the radiative modes will be closed by including the contributions of the evanescent modes. These results are of general importance and relevance to the spontaneous emission by an atom or to dipole radiation in 2D periodic structures. In addition, it may serve as an efficient approach to identifying the existence of a complete photonic band gap in a 2D PC instead of using time-consuming 3D BS calculations.