Surface plasmon polaritons excitation by second-harmonic generation in KNbO 3 nanowires deposited on thin Ag and Au films

Abstract

We present here an alternative approach to local nanoscale light sources for excitation of surface plasmons based on second-harmonic generation (SHG) in inorganic crystalline nanowires. It is shown that the nanowires can serve as tunable coherent local source for surface plasmon polariton (SPP) excitation. Inorganic crystalline nanowires made of potassium niobate (KNbO 3 ) have previously been shown to have a large second-order optical non-linearity, which allows for efficient second-harmonic- and sum-frequency generation. It has also been demonstrated that the fields generated by scattering off nanfibers deposited on an air/metal interface can couple to SPP modes at the interface and thereby excite SPPs at the interface. We have combined SHG in nanowires with SPP excitation through scattering off nanowires deposited on thin silver and gold surfaces. To detect second-harmonic radiation that has been efficiently coupled into SPP modes at the air/metal interface, angular resolved leakage radiation spectroscopy was performed for pump wavelengths between 800 and 1300 nm. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).