# Surface plasmon-polariton waves obliquely guided along interface containing periodicity direction of one-dimensional photonic crystal

## TL;DR

This paper develops a comprehensive formulation for oblique surface plasmon-polariton waves at the interface with a one-dimensional photonic crystal, revealing bandgaps and periodicity in their propagation characteristics.

## Contribution

It introduces a general formulation and dispersion equation for oblique SPP waves supported by photonic crystal interfaces, including numerical solutions and analysis of plasmonic bandgaps.

## Key findings

- Observation of periodicity in SPP wave wavenumbers
- Identification of plasmonic bandgaps in the photonic band diagram
- Potential for designing optical filters using these bandgaps

## Abstract

We recently formulated the canonical boundary-value problem of propagation of surface plasmon-polariton (SPP) waves along the direction of periodicity of a one-dimensional photonic crystal. Here we present the general formulation of that canonical problem supporting the oblique propagation of SPP waves in the interface plane. The general dispersion equation has been obtained using the rigorous coupled-wave approach for the oblique propagation and numerically solved using the Muller's method. A periodicity in the wavenumbers of the SPP waves was observed. Furthermore, the regions of high losses for the SPP waves, dubbed as plasmonic bandgaps, were observed in the photonic band diagram of the SPP waves. These plasmonic bandgaps can be used to construct optical filters for the SPP waves.