# Unidirectional reflectivity in non-Hermitian lossy thin films

## TL;DR

This paper investigates unidirectional reflectivity in non-Hermitian lossy thin films, demonstrating controlled optical reflection and transmission for potential use in optical diodes and entangled photon sources.

## Contribution

It introduces a novel approach to achieve unidirectional reflection in layered thin films using non-Hermitian properties and transfer matrix methods.

## Key findings

- Unidirectional reflection achieved in lossy thin film stacks
- Transfer matrix methods effectively model the system
- Finite element simulations confirm the theoretical results

## Abstract

Inspired by non-Hermitian systems, we study reflection and transmission in a stack of thin films composed by the repetition of a bipartite unit cell. We aim for controlled reflection and transmission using lossless and lossy materials in order to develop an optical diode to generate entanglement photons source. Particularly, we show unidirectional reflection using transfer matrix methods and confirm our results by finite element simulation.