Polarization-resolving graphene-based mid-infrared detector

TL;DR

This paper demonstrates a graphene-based mid-infrared detector capable of resolving light polarization with a single device, leveraging gate voltage-dependent photoresponse to distinguish polarization states.

Contribution

It introduces a novel polarization-resolving detector using a single graphene device with dissimilar metal contacts, avoiding the need for multiple detectors or external polarizers.

Findings

The detector can distinguish orthogonal polarizations with a ratio of ~10.

Gate voltage tuning enables polarization-insensitive calibration and high sensitivity.

The polarization dependence arises from competing photovoltage pathways.

Abstract

The ability to resolve the polarization of light with on-chip devices represents an urgent problem in optoelectronics. The detectors with polarization resolution demonstrated so far mostly require multiple oriented detectors or movable external polarizers. Here, we experimentally demonstrate the feasibility to resolve the polarization of mid-infrared light with a single chemical-vapor-deposited graphene-channel device with dissimilar metal contacts. This possibility stems from an unusual dependence of photoresponse at graphene-metal junctions on gate voltage and polarization angle. Namely, there exist certain gate voltages providing the polarization-insensitive signal; operation at these voltages can be used for power calibration of the detector. At other gate voltages, the detector features very strong polarization sensitivity, with the ratio of signals for two orthogonal polarizations reaching ~10. Operation at these voltages can provide information about polarization angles, after the power calibration. We show that such unusual gate- and polarization-dependence of photosignal can appear upon competition of isotropic and anisotropic photovoltage generation pathways and discuss the possible physical candidates.