# Constructing a partially transparent computational boundary for UPPE using leaky modes

## TL;DR

This paper presents a novel method for creating a partially transparent computational boundary in optical simulations using leaky modes and artificial-index materials, reducing reflections more effectively than traditional PMLs.

## Contribution

The authors introduce a new boundary construction technique employing leaky modes and artificial materials, enhancing spectral propagator simulations of optical wave propagation.

## Key findings

- Significantly reduced boundary reflections in optical simulations.
- Effective for spectral propagators and TE electromagnetic waves.
- Outperforms traditional PML methods in specific scenarios.

## Abstract

In this paper we introduce a method for creating a transparent computational boundary for the simulation of unidirectional propagation of optical beams and pulses using leaky modes. The key element of the method is the introduction of an artificial-index material outside a chosen computational domain and utilization of the quasi-normal modes associated with such artificial structure. The method is tested on the free space propagation of TE electromagnetic waves. By choosing the material to have appropriate optical properties one can greatly reduce the reflection at the computational boundary. In contrast to the well-known approach based on a perfectly matched layer, our method is especially well suited for spectral propagators.