Broadband Graphene Polarizer Invented

A graphene-based polarizer that can broaden the bandwidth of prevailing optical fiber-based telecommunications systems has been invented by researchers at National University of Singapore (NUS).

The team, led by professor Kian Ping Loh, invented an ultraslim broadband polarizer that uses graphene to convert a light beam into polarized light. This is the first experimental demonstration of using graphene as an ultrathin waveguide to couple and modulate light. Light modulation by means of polarization management is vital to avoiding signal fading and error in coherent optical communications as well as optical gyroscopes and interferometric sensors.

In principle, the polarizing ability of graphene covers the telecommunication bands from visible to mid-infrared. This means that graphene polarizer can provide all-in-one solution for multiple-channel high-speed optical communications, the researchers say.

The team transferred graphene grown by chemical vapor deposition on the side-polished optical fiber to fabricate the graphene polarizer and measured light polarization at different wavelengths. Unlike polarizers made from thin metal film or semiconductor dielectric, a graphene polarizer has the unique ability to filter out transverse-magnetic-mode, and it supports transverse-electric-mode surface wave propagation.

“[These] results can have a strong impact in the development of graphene-based optical devices for photonic applications — the science behind it is excellent,” said professor Antonio Castro Neto of NUS.

The Singapore team pioneered graphene mode-locked lasers in 2009. This work was another breakthrough in bringing graphene photonics a step closer to real applications.

“In the near future, we can envision ultrathin graphene-based photonic circuits with multiple functions of light creation, routing, modulation or detection,” said Dr. Qiaoliang Bao, the project leader.

This work was published in the journal Nature Photonics.

For more information, visit: www.nus.edu.sg