Radially-polarized surface plasmon microscopy for sensitive detection of nanometric-sized fluorescent spheres and nonlinearly active nanocrystals

Surfac plasmon sensors use transverse magnetic (TM) polarized waves to probe minor refractive index (RI) changes occurring at an interface between a metal film and a dielectric medium. For optical microscopy, SPR phenomena may be taken advantage of to increase the signal- to-noise ratio so as to benefit to the spatial resolution in imaging applications. This paper presents a demonstration performed by scanning over a few scattering sources of sub micrometer size. In order to get a higher sensitivity studies for nanoparticles, a new development of radially polarized surface plasmon microscopy with two detection channels for linear reflection and epifluorescence, as well as a modulation detection scheme based on an annular disc, is reported.