# Ultrafast modulation in a THz graphene-based flat absorber through negative photoconductivity

## TL;DR

This paper demonstrates an ultrafast graphene-based THz absorber modulator that uses negative photoconductivity to achieve rapid control of absorption, enabling advanced flat optics and metasurface applications.

## Contribution

It introduces a novel graphene-based flat absorber modulator operating in the THz range with ultrafast modulation via negative photoconductivity, supported by experimental and theoretical analysis.

## Key findings

- Ultrafast modulation achieved in THz regime.
- Hot carrier generation reduces graphene conductivity.
- Potential for flat optics and metasurface applications.

## Abstract

We present the experimental and theoretical study of an ultrafast graphene based thin film absorption modulator for operation in the THz regime. The flat modulator is composed of a graphene sheet placed on a dielectric layer backed by a metallic back reflector. A near IR pulse induces the generation of hot carriers in the graphene sheet reducing effectively its conductivity. The system provides a platform with ultrafast modulation capability for flat optics and graphene based metasurfaces applications.

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Source: https://tomesphere.com/paper/1908.06696