Surface plasmon resonance in ITO using a PMMA grating coupler

Abstract To couple the incident light with surface plasmons, polymethyl methacrylate (PMMA) grating couplers with a period of 1 μm were fabricated on ITO thin films using thermal nanoimprint lithography. Gratings with different heights were prepared to examine how their structural parameters influence the reflectance spectra associated with ITO surface plasmon resonance (SPR). Removal of the residual PMMA at the bottom of the grating grooves by oxygen plasma enabled clear observation of an SPR-induced reflectivity dip in the polarization-dependent reflection spectra. The dip depth increased with grating height and reached a maximum of approximately 50% at a height of 400 nm. The experimental results showed good agreement with the finite-difference time-domain simulation results.