Graphene for Enhanced Metal Plasmonics

Abstract

The experimental work undertook in this thesis looks to integrate technologies developedby the graphene and plasmonics communities, respectively, for the purpose of producingdevices of enhanced qualities to those of similar utility that have previously been produced.Furthermore, where possible, we look to offer disruptive innovation, by utilising coupledproperties that may offer unique possibilities for applications.A hybrid graphene-plasmonic waveguide modulator is fabricated and shown to operatesuccessfully at a standard telecommunications frequency. Different plasmonic-waveguidedesigns - the basis for the modulator - were produced to probe the coupling betweengraphene and the surface plasmon-polariton modes. A mode excitable at the edge ofthe waveguide was found to offer the best modulation, with a modulation depth of over0.03 dB micro metre^-1, induced by a moderate gating voltage of about 10 V.Topologically-protected darkness (zero reflection) was produced by particular engineeringof a plasmonic metamaterial. This allowed generation of a singularity in the ellipsometricphase (a particular parameter of light), allowing for measurements of mass sensitivityof ∼10 fg mm^-2, with the possibility of improving this to ∼100 ag mm^-2. Graphene wasemployed in a novel metrology tool to measure the sensitivity of this device.With respect to fundamental losses in plasmonics, one could find either find a new plasmonicmaterial or look to improve an existing one. Work was undertook with respect to this latteroption by attempting to preserve the otherwise excellent plasmonic properties of copper andsilver through a protective barrier of graphene. This was achieved and illustrated throughellipsometric measurements taken over various timescales. Fabrication of a dielectricloadedwaveguide on graphene-protected copper was then carried out, with operation ofthe waveguide proving successful, possibly opening the field of active graphene-protectedmetal plasmonics.

Date of Award	1 Aug 2015
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Alexander Grigorenko (Supervisor)