Graphene-based Plasmonic Phototransistor Provides Broadly Tunable, Narrowband Photoresponse

Abstract

UCF researchers have invented a graphene phototransistor providing a narrowband photoresponse that is broadly tunable over a wide frequency range. The detector can be adapted to produce tunable phototransistors operable in the spectral range from ultraviolet (UV) to mm-waves, as well as the entire infrared and THz region. This mechanism is based on resonant gating of graphene by the concentrated, dynamic electric fields of surface plasmon polaritons (SPPs) and it forms the basis for tunable, high-speed imaging arrays.

Technical Details

Within the graphene phototransistor, photodetection occurs through an innovative combination of two transduction steps. 1) Incident photons are instantly converted with high efficiency to SPPs. 2) The SPP fields produce a measurable perturbation on graphene transport, where high speed is anticipated due to graphene's high room-temperature carrier mobility and by potentially light-like speeds for information transfer via SPP propagation.

The graphene sheet is positioned at the surface of a suitable photon-to-SPP excitation coupler. The SPPs are excited at a specific angle of incidence for a given wavelength. The intense SPP fields, in turn, penetrate, gate, dynamically dope, and excite traveling waves of charge density in the graphene, causing changes in its conductance by a variety of potential mechanisms that are sensed electrically.

Benefit

Market Application