Applied Nanophotonics, Liquid Crystals and Biomedical Optics

A novel (to our knowledge) concept for a tunable birefringent filter with a high dynamic range is proposed and demonstrated by using a stack of liquid-crystal retarders having different thicknesses following an arithmetic sequence. Each retarder is between crossed polarizers with its optic axis oriented azimuthally at 45° to the polarizer axis. The tunable filter was fabricated by using nematic liquid crystals demonstrating tunability over a range of 800 nm, covering the visible and the near IR; hence it has a potential for use in biomedical optical imaging applications.