LYKOURGOS BOUGAS, G. E. KATSOPRINAKIS, T. P. RAKITZIS, Department of Physics, University of Crete, and Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas 71110 Heraklion-Crete, Greece.
We demonstrate the absolute measurement of optical rotation using a four-mirror cavity-ring-down polarimetric setup. A four-mirror bow-tie cavity allows counter-propagating laser beams, for which symmetry is broken with a longitudinal magnetic field acting upon an intracavity magneto-optic window (producing a Faraday rotation
_F). A chiral sample is introduced in one arm of the cavity, producing a chiral rotation
__C. The different symmetry of the two rotations produces a total rotation of (
__C) for one laser beam, and (
__C) for the counter-propagating beam. These rotations produce a polarization beating in the cavity ring-down, of frequency
__CCW for the clockwise and counter-clockwise beams, respectively. Analysis of the difference (
__CCW) yields the chiral rotation angle \pm
__C, where the sign of the angle is determined by the sign of the applied magnetic field. Therefore, subtracting the signals using +\vecB and Ð\vecB yields 2
__C, allowing the absolute determination of
__C, without needing to remove the sample . We demonstrate these absolute optical rotation measurements for chiral gases (
-pinene) and chiral liquids.
This work is a proof-of-principle demonstration of the experimental setup proposed for the measurement of parity non-conserving optical rotation in atomic systems .
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