# Polarization-Insensitive Electro-Optic Modulator for the Terahertz Regime Enabled by a Graphene-Hybrid Plasmonic Waveguide

## TL;DR

A new graphene-based optical modulator works well at terahertz frequencies and is insensitive to light polarization, making it useful for advanced photonic applications.

## Contribution

A polarization-insensitive graphene-hybrid plasmonic modulator is proposed with ultra-broadband performance and CMOS compatibility.

## Key findings

- The modulator achieves 0.247 dB/μm maximum attenuation at 3 THz with a low polarization-dependent error.
- The device operates effectively at 2.5 THz and is compatible with CMOS technology.
- The design enables synchronous control of TE/TM modes via Fermi level tuning.

## Abstract

A polarization-insensitive compact optical modulator based on a graphene-hybrid surface plasmon polariton waveguide is proposed. The inverted U-shaped structure enables the synchronous control of TE/TM modes via Fermi level tuning, achieving a maximum attenuation of 0.247 dB/μm (Ef = 0.3 eV) and a minimum attenuation of 0.026–0.028 dB/μm (Ef = 1.0 eV) at 3 THz, with a polarization-dependent modulation error of only 0.002 dB/μm. The 100 μm × 30 μm device operates effectively at 2.5 THz (120 μm), demonstrating its potential for integrated photonic circuits. Additionally, the proposed modulator is compatible with Complementary Metal-Oxide-Semiconductor (CMOS) technology. The excellent ultra-broadband modulation performance of the graphene-hybrid plasmonic waveguide (GHPW) thereby paves the way for high-speed communication, non-destructive testing, biomedical sensing and optical computing.