Photodetection and sensing with graphene using surface plasmon polaritons

New publication in Nano Letters shows how light can be converted into surface plasmon polaritons which then are transduced into an electrical signal by a graphene-based detector.

Spatial photoresponse of a surface plasmon polariton graphene-based photodetector.
Spatial photoresponse of a surface plasmon polariton graphene-based photodetector.

Collaborative research between Dr. Tim Echtermeyer of the Microelectronics and Nanostructures research group in the School of Electrical and Electronic Engineering, Prof. Elefterios Lidorikis of the University of Ioannina, Greece and the Cambridge Graphene Centre, directed by Prof. Andrea Ferrari has led to a publication in the journal Nano Letters showing how light can be converted into surface plasmon polaritons which then are transduced into an electrical signal by a graphene-based detector. 

The research demonstrates how the responsivity and photoactive area of graphene-based photodetectors can be enhanced by 400% and 1000%, respectively. As opposed to previous graphene-based photodetector designs where the metal contacting the graphene has played a passive role for light detection, the metal contacts are now structured into plasmonic grating-couplers that allow incident light to excite surface plasmon polaritons (SPPs) in the contacts. These SPPs then travel along the contact until they reach the graphene channel where they are transduced into an electrical signal. By appropriately designing the contacts it is possible utilize SPP-interference effects for tuning the spectral response of the photodetectors.

Calculations show that these SPP-interference effects can not only be used for photodetection but also for (bio-) sensing. Interference effects are highly sensitive to phase-shifts between the interfering waves and it is possible to detect the attachment of analytes onto the sensor surface with high sensitivity. As opposed to conventional surface plasmon resonance (SPR) sensors which rely on an optical readout and bulky optics it is now possible to directly read-out the sensor’s signal electrically, opening a route for further miniaturization of SPR-based sensors.

For more information see:

T.J. Echtermeyer, S. Milana, U. Sassi, A. Eiden, M. Wu, E. Lidorikis, and A.C. Ferrari, “Surface Plasmon Polariton Graphene Photodetectors”, Nano Lett., Dec. 2015, DOI: 10.1021/acs.nanolett.5b02051

 

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