Coherent illumination spectroscopy of nanostructures and thin films on thick substrates

Many nanophotonic and nanoelectronic devices contain nanostructures and ultrathin films on the surface of a thick, effectively semi-infinite, substrate. Here we consider a spectroscopic technique based upon coherent illumination, for characterising such samples. The method uses two counter-propagating light beams to generate specific field configurations at the substrate surface plane, which can be modulated, for example, to selectively excite and thereby discriminate between resonant modes of plasmonic nanostructures, or to measure thin films thickness with nanometre resolution. The technique offers a variety of practical applications for the coherent illumination in solid state physics, analytical chemistry, biochemistry, and nano-engineering.