Local excitation of surface plasmon polaritons by second-harmonic generation in crystalline organic nanofibers

Coherent local excitation of surface plasmon polaritons (SPPs) by second-harmonic generation (SHG) in aligned crystalline organic functionalized para-phenylene nanofibers deposited on a thin silver film is demonstrated. The excited SPPs are characterized using angle-resolved leakage radiation spectroscopy in the excitation wavelength range of 850-1325 nm and compared to simulations based on a Green’s function area integral equation method. Both experimental and theoretical results show that the SPP excitation efficiency increases with decreasing wavelength in this wavelength range. This is explained both as a consequence of approaching the peak of the fibers nonlinear response at the wavelength 772 nm, and as a consequence of better coupling to SPPs due to their stronger confinement.