Low-loss metal-dielectric waveguide mode enabled structured illumination microscopy with 0.18λ

Structured illumination microscopy (SIM) is a powerful super-resolved imaging technique which enables to perform fast and in vivo imaging of bio-samples. In order to achieve a better resolution of a SIM system, evanescent waves with larger in-plane wave-vector are preferred for SIM, among which the total internal reflection (TIRF-SIM) and the plasmonic SIM (pSIM) configurations are widely studied. Here, we demonstrated a metal-dielectric waveguide (MDW) based SIM system - termed as MDW-SIM, which can achieve a good compromise between TIRF-SIM and pSIM. The MDW can support a low-loss waveguide mode at an aqueous environment, with an evanescent tail existing above the water/dielectric interface for SIM. A proof-of-concept imaging experiment was performed on fluorescent beads, where a spatial resolution of 86nm was achieved at a 473nm illumination wavelength and a 1.45 numerical aperture objective lens. The proposed MDW-SIM has a great potential for the bio-imaging applications.