# Tunable Optical Bistability in Asymmetric Dielectric Sandwich with Graphene

## TL;DR

This paper explores how graphene in asymmetric dielectric structures can control optical bistability in terahertz frequencies, enabling new photonic devices.

## Contribution

The study introduces a tunable optical bistability mechanism using asymmetric graphene-dielectric structures in the terahertz range.

## Key findings

- Bistable behavior is modulated by incident angle, wavelength, and dielectric layer properties.
- Asymmetric structures reduce transmittance while symmetric ones enhance it.
- Bistability thresholds decrease with increasing wavelength but increase with thicker or higher permittivity dielectric layers.

## Abstract

This study theoretically investigates the nonlinear optical response of asymmetric dielectric structures embedded with graphene and demonstrates tunable optical bistability in the terahertz frequency range. Our findings reveal that the bistable behavior can be effectively modulated by varying the incident angle, the working wavelength, and the thickness and permittivity of the dielectric layers. In symmetric dielectric configurations, transmittance is enhanced, whereas in asymmetric structures, it is reduced. The thresholds of optical bistability decrease with increasing wavelength of the incident light, while they increase with thicker dielectric layers or higher permittivity of the dielectric medium. Furthermore, widening the bistability range can be achieved by increasing the incident angle. The proposed asymmetric graphene–dielectric layered structure offers a promising platform for the development of advanced terahertz active photonic devices, including optical modulators, optical switches, and mid-infrared functional components.