Low-loss dielectric-loaded graphene surface plasmon polariton waveguide based biochemical sensor

Thamani M Wijesinghe,Malin Premaratne,Govind P Agrawal

doi:10.1063/1.4922124

Thamani M Wijesinghe, Malin Premaratne + Show 1 more

Open Access

https://doi.org/10.1063/1.4922124

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Abstract

We have modeled and numerically simulated the performance of a dielectric-loaded graphene surface-plasmon-polariton (DL-GSPP) waveguide as a biochemical sensing device. In our device, the conventionally used gold layer is replaced with a graphene microribbon for the detection of biochemical molecules. The graphene layer is incorporated to minimize ohmic losses and to enhance the adsorption of biomolecules so that the sensor sensitivity is increased significantly. The sensor performance is quantified through numerical simulations carried out by varying device parameters such as waveguide length, effective mode index, dimension of the dielectric ridge, and the length and the number of graphene layers. One of the prominent features of our DL-GSPP waveguide sensor is that its length is in the millimeter range, an essential requirement for realistic plasmonic waveguide sensors. The average sensitivity of DL-GSPP structure is found to be in the range of 3–6 μRIU (refractive index units), which is comparable to the values obtained using surface-plasmon resonance (1–10 μRIU) and long-range waveguide sensors (0.1–5 μRIU).

Highlights

As surface-plasmon-polariton (SPP) modes are laterally confined on a sub-wavelength scale, plasmonics have been employed to realize many efficient nano/micro devices
Highly doped, it behaves like a thin metal film and allows for the guiding of transverse-magnetic (TM)-polarization SPPs
We demonstrate that a dielectric-loaded graphene SPP (DL-GSPP) waveguide can be exploited as a sensing device

Summary

INTRODUCTION

Plasmonics has attracted significant attention over the past few decades, owing to the revolutionary impacts that it has on both the fundamental physics and practical applications in various disciplines. As surface-plasmon-polariton (SPP) modes are laterally confined on a sub-wavelength scale, plasmonics have been employed to realize many efficient nano/micro devices. As one of the first commercial applications of plasmonic techniques, SPPs are used to build biological and chemical sensors with greater sensitivity compared to conventional sensing methods. Biosensors are used in the fields of drug discovery, medical diagnosis, and detection of harmful pathogens. A monolayer of graphene with very low chemical potential behaves like a semiconductor and supports guiding of a transverse-electric (TE)-polarization SPPs.. Highly doped, it behaves like a thin metal film and allows for the guiding of transverse-magnetic (TM)-polarization SPPs. Similar to a thin metal stripe that supports low-loss, LRSPP stripe modes, graphene microribbons can guide long-range graphene SPP (LR-GSPP) stripe modes. Similar to a thin metal stripe that supports low-loss, LRSPP stripe modes, graphene microribbons can guide long-range graphene SPP (LR-GSPP) stripe modes Such modes exhibit an average extinction ratio of 19 dB at a wavelength of 1.31 lm and have been used successfully in experiments for data transmission at a bit rate of 2.5 Gb/s.27–29. We demonstrate that a dielectric-loaded graphene SPP (DL-GSPP) waveguide can be exploited as a sensing device.

DL-GSPP WAVEGUIDE

OUTPUT POWER AND SENSITIVITY

Findings

DISCUSSION AND CONCLUSIONS