An efficient optical filter can be made by modifying the birefringent Fabry-Perot interferometer. The addition of a pair of quarter-wave plates gives a response that previously was thought to be obtainable only with active elements, such as Faraday rotators.
J. H. WILLIAMSON, "Simple Multiple-Pass Birefringent Filters," J. Opt. Soc. Am. 61, 767-769 (1971)