Broadband spectral shaping using nematic liquid crystal

Abstract

We demonstrate what is, to our knowledge, the first implementation of nematic liquid crystal (LC) for spectral shaping of broadband light fields. A LC cell of several microns thickness is placed between a polarizer and an analyzer. By changing the analyzer angle, one can use the combined device as a spectral filter of different types, such as a notch filter, narrow-band filter etc. We also demonstrate that the source spectrum also gets manipulated by changing the LC cell thickness and by tuning the voltage applied across the LC cell, providing another degrees of freedom for shaping the broadband spectrum. Such important effect using liquid crystals can find technological applications in spectral shaping of light fields by making variable spectral filters, and in spectral switching based data communication schemes. Keywords: Birefringence, Polarization, Spectral switching