Graphene photodetectors for high-speed optical communications

TL;DR

This paper demonstrates the first use of graphene as a photodetector in a 10 Gbps optical data link, achieving high responsivity and ultra-wide wavelength operation, advancing high-speed optical communication technology.

Contribution

It introduces a novel graphene-based photodetector with asymmetric metallization, enabling efficient broadband detection in optical communications.

Findings

Maximum responsivity of 6.1 mA/W at 1.55 μm

Operational wavelength range from 300 nm to 6 μm

Successful deployment in a 10 Gbps data link

Abstract

While silicon has dominated solid-state electronics for more than four decades, a variety of new materials have been introduced into photonics to expand the accessible wavelength range and to improve the performance of photonic devices. For example, gallium-nitride based materials enable the light emission at blue and ultraviolet wavelengths, and high index contrast silicon-on-insulator facilitates the realization of ultra dense and CMOS compatible photonic devices. Here, we report the first deployment of graphene, a two-dimensional carbon material, as the photo-detection element in a 10 Gbits/s optical data link. In this interdigitated metal-graphene-metal photodetector, an asymmetric metallization scheme is adopted to break the mirror symmetry of the built-in electric-field profile in conventional graphene field-effect-transistor channels, allowing for efficient photo-detection within the entire area of light illumination. A maximum external photo-responsivity of 6.1 mA/W is achieved at 1.55 {\mu}m wavelength, a very impressive value given that the material is below one nanometer in thickness. Moreover, owing to the unique band structure and exceptional electronic properties of graphene, high speed photodetectors with an ultra-wide operational wavelength range at least from 300 nm to 6 {\mu}m can be realized using this fascinating material.