Broadband light generation from Au–Al2O3–Al sub-10 nm plasmonic gap structures

Abstract

We demonstrate broadband photoluminescence (PL) from a Au nanorod–alumina–Al substrate (Au–Al₂O₃–Al) sandwich structure under a peak excitation power intensity of 1.45–2.61 GW cm⁻². The emission wavelength is in the range of 450–1050 nm and the lifetime is on the sub-nanosecond timescale. Comparative studies of the PL from Au–Al₂O₃–Al with different Au rod lengths and Au–Al₂O₃ without an Al coupling layer, together with finite difference time domain (FDTD) calculations, show that the PL from Au–Al₂O₃–Al originates from the surface plasmon enhanced supercontinuum (SC) generation in the Al₂O₃ membrane. This observation indicates that a SC could be realized in nanoscale plasmonic structures, which has promising applications in the minimization and integration of light sources in photonic devices.