Direct measurement of increased light intensity in optical waveguides coupled to a surface plasmon spectroscopy setup

The local increase of light intensity in waveguide structures was monitored by a combination of conventional surface plasmon spectroscopy and a dye-sensitized solar cell (DSSC). The sensitized nanoporous TiO2 layer of the DSSC served both as waveguide structure and light absorber in the DSSC. If the conditions for the excitation of guided modes in the TiO2 waveguide structure were fulfilled, increased light intensity in the porous layer was monitored by an increase of short circuit current in the DSSC. Comparison with direct illumination yields an increase of intensity by a factor of 19±6, in good agreement with transfer matrix calculations.