HF-sputtered glass waveguide slides for waveguide evanescent field microscopy

Waveguide evanescent field microscopy (WEFM) relies on a particular strongly interface confined dark field illumination technique where guided modes interact with the specimen deposited on top of the film by their evanescent field tails. We report on the deposition of high refractive index P-LASF-47-glass films on silica substrate slides by a high-frequency sputtering technique. The resulting step-index waveguides are optimized for green and red HeNe-laser radiation and can support up to three guided modes both for s- and p-polarization. For mode excitation the silica substrates have been provided with a coupling grating formed by interference lithography and subsequent ion beam etching. The waveguide films have been characterized by m-line- spectroscopy, spectral reflectometry and AFM-scans. They showed homogeneous coupling gratings, very narrow m-lines and proved resistance against combined chemical/ultrasound cleaning procedures. We found that the refractive index of the deposited glass film has been increased with respect to its bulk value by appr. 3%. The slide performance when implemented into a microscopic set-up has been demonstrated.