Electrically Tunable Four-Wave-Mixing in Graphene Heterogeneous Fiber for Individual Gas Molecule Detection

TL;DR

This paper presents a novel integrated photonic sensor using graphene heterojunction fiber that achieves real-time detection of individual gas molecules through electrically tunable four-wave mixing, overcoming noise limitations of traditional devices.

Contribution

It introduces a new all-fiber, electrically tunable four-wave mixing scheme in graphene heterojunctions enabling single-molecule gas detection, a significant advance over existing photonic sensors.

Findings

Steep FWM efficiency change near graphene Fermi level 0.4 eV

Real-time detection of individual gas molecules in vacuum

Integration of graphene nonlinearities with fiber optics

Abstract

Detection of individual molecules is the ultimate goal of any chemical sensor. In the case of gas detection, such resolution has been achieved in advanced nanoscale electronic solid-state sensors, but it has not been possible so far in integrated photonic devices, where the weak light-molecule interaction is typically hidden by noise. Here, we demonstrate a scheme to generate ultrasensitive down-conversion four-wave-mixing (FWM) in a graphene bipolar-junction-transistor heterogeneous D-shaped fiber. In the communication band, the FWM conversion efficiency can change steeply when the graphene Fermi level approaches 0.4 eV. In this condition, we exploit our unique two-step optoelectronic heterodyne detection scheme, and we achieve real-time individual gas molecule detection in vacuum. Such combination of graphene strong nonlinearities, electrical tunability, and all-fiber integration paves the way toward the design of versatile high-performance graphene photonic devices.