US Patent 9702812 Cavity enhanced polarimeter and related methods

A polarimeter for measuring chirality of a material comprising an optical ring cavity comprising a plurality of reflective elements configured to promote bi-directional propagation of a laser beam within the cavity, a laser-emitting device configured to introduce a first input laser beam and a second input laser beam into the ring cavity, and a Faraday rotator and a phase compensator configured to suppress a birefringent background as the first and second laser beams pass through the ring cavity, wherein the plurality of mirrors, Faraday rotator, and phase compensator are configured such that light from the first and second laser beams passes through a chiral material located within the cavity a sufficient number of times for a measurement of optical rotary dispersion (ORD) and circular dichroism (CD) of light transmitted through the chiral material to be obtained. Particular implementations include monolithic ring cavities or microresonators or use of intra-cavity gain media.