Multichannel probes for polarization-resolved scanning near-field optical microscopy

International audienceWe propose and validate a concept of multichannel near-field fiber probe for the collection and discrimination of optical fields of orthogonal polarizations (linear, elliptic, and circular). The system is achieved by connecting to scanning near-field optical microscope fiber tips an optical stage made up of commercial polarizers, fiber couplers, and polarization controllers. Using radially polarized Bessel beams as test objects, we demonstrate the ability of a three-channel fiber tip to simultaneously and independently probe the transverse vector components of the electric field (parallel to the sample surface) and the overall transverse intensity. The polarization ratio of the near-field collection system exceeds 1:1500. The system can be implemented in collection-mode or reflection-mode near-field microscope configurations, with various kinds of probe and light source (of high or low coherence lengths) for a deeper insight of light polarization effects and vector fields at a subwavelength scale