# Graphene-Loaded LiNbO3 Directional Coupler: Characteristics and Potential Applications

## TL;DR

This paper shows how adding graphene to lithium niobate waveguides improves light control and temperature sensitivity, useful for photonic circuits and sensors.

## Contribution

The novel integration of graphene with LiNbO3 waveguides enables enhanced coupling efficiency and thermal sensitivity for photonic applications.

## Key findings

- Graphene loading alters the effective mode refractive index and enhances waveguide coupling.
- Graphene–LN structures show strong thermal sensitivity with temperature-induced changes in output power ratios.
- The integration supports compact photonic circuits and temperature sensing applications.

## Abstract

This study explores the impact of graphene integration on lithium niobate (LiNbO3, LN) ridge waveguides and directional couplers, focusing on coupling efficiency, polarization-dependent light absorption, and temperature sensitivity. Experimental and simulation results reveal that graphene loading significantly alters the effective mode refractive index and enhances waveguide coupling, enabling precise control over light transmission and power distribution. The temperature-dependent behavior of graphene–LN structures demonstrates strong thermal sensitivity, with notable changes in output power ratios between cross and through ports under varying temperatures. These findings highlight the potential of graphene–LN hybrid devices for compact, high-performance photonic circuits and temperature sensing applications. This study provides valuable insights into the design of advanced integrated photonic systems, paving the way for innovations in optical communication, sensing, and quantum technologies.