Spacerless circular-polarization spectral-hole filters using chiral sculptured thin films: theory and experiment

In the Bragg wavelength regime, a sculptured thin film with chiral micromorphology permits light of a particular circular polarization state to pass virtually unhindered, but light of the other polarization state is reflected almost completely. On cascading two such films, but with one film twisted with respect to the other by an angle of 90 degrees, a hole appears in the reflection spectrum. This is proved theoretically as well as experimentally in this paper. Also, it is shown that the design wavelength of the filter can be tuned by a modest amount by tilting the filter with respect to the incident beam, (C) 2000 Elsevier Science B.V. All rights reserved.