Electric current-driven spectral tunability of surface plasmon polaritons in gold coated tapered fibers

Tilman Lühder,Torsten Wieduwilt,Henrik Schneidewind,Markus A Schmidt

doi:10.1063/1.5046991

Tilman Lühder, Torsten Wieduwilt + Show 2 more

Open Access

PDF Available

https://doi.org/10.1063/1.5046991

Copy DOI

Export

Save

Cite

Abstract
Highlights/Summary
Full-Text PDF
Similar Papers

Abstract

Listen

Here we introduce the concept of electrically tuning surface plasmon polaritons using current-driven heat dissipation, allowing controlling plasmonic properties via a straightforward-to-access quantity. The key idea is based on an electrical current flowing through the plasmonic layer, changing plasmon dispersion and phase-matching condition via a temperature-imposed modification of the refractive index of one of the dielectric media involved. This scheme was experimentally demonstrated on the example of an electrically connected plasmonic fiber taper that has sensitivities &gt;50000 nm/RIU. By applying a current, dissipative heat generated inside metal film heats the surrounding liquid, reducing its refractive index correspondingly and thus modifying the phase-matching condition to the fundamental taper mode. We observed spectral shifts of the plasmonic resonance up to 300 nm towards shorter wavelength by an electrical power of ≤ 80 mW, clearly showing that our concept is important for applications that demand precise real-time and external control on plasmonic dispersion and resonance wavelengths.

Highlights

Due to unique properties such as nanoscale light confinement and customized dispersion, surface plasmon polaritons (SPPs) have attracted substantial attention by the photonics community during recent times with applications in areas such as bioanalytics,[1] nonlinear photonics[2] and quantum technology.[3]
Increasing the current imposes the plasmonic resonance to shift to shorter wavelengths, which overall is a result of the combination of dissipative heat and negative thermo-optical response
The spectral shift is independent on the sign of the applied voltage, verifying that dissipative heating is the origin of the observed effect and that any current-driven thermal contribution imposed by the aluminum/gold interface is either too small to be measured or negligible since the region of interest is in the center of both interfaces, leading to an effect of opposite sign.[32,33]

Summary

INTRODUCTION

Due to unique properties such as nanoscale light confinement and customized dispersion, surface plasmon polaritons (SPPs) have attracted substantial attention by the photonics community during recent times with applications in areas such as bioanalytics,[1] nonlinear photonics[2] and quantum technology.[3]. The overall idea of the tuning concept discussed here is to generate electrical current-driven dissipative heat inside the plasmonic layer that heats up the dielectric surrounding the metal film This increased temperature imposes the RI of the dielectric to change, which, in turn, modifies the PM conditions between dielectric and plasmonic mode, leading to a macroscopically measurable spectral shift of the SPP resonance. To provide PM between plasmonic and taper modes, a defined section of the taper waist (length 2.8 mm) was immersed into the mentioned oils which have precisely known material dispersion (Cargille RI oils, identified by the base RI nD at 589 nm and 25 ◦C), increasing the RI of the most outer dielectric influencing the SPP dispersion such to provide PM Due to their large negative thermooptical coefficient (see Table I, fused silica as reference 27), the RI of the liquid decreases in case the current-driven heat is increased. As only a small part of the spectrum is transmitted out of the sensor any heating originating from the sensor itself was negligible

RESULTS

CONCLUSION