BIREFRINGENT RUGATE FILTERS

The design and fabrication of a birefringent rugate filter (birugate) is discussed. Zirconium oxide was deposited onto a slowly oscillating substrate to produce an optical medium with a sinusoidally modulated c olumnar microstructure. The modulated medium is inhomogeneous and biax ial but normally incident beams of p and s polarised light propagate w ithout cross-coupling. The birugate has displaced p and s transmittanc e peaks, and has potential uses in optical communications.