Optical-rotatory-dispersion measurement approach using the nonlinear behavior of the geometric phase

We propose a method for high-sensitivity optical rotatory dispersion (ORD) measurement of optically active samples that takes advantage of the nonlinear behavior of the geometric phase (GP). To measure the GP as a function of wavelength, we use a multichannel Fourier transform spectrometer (MC-FTS) that is based on Savart plate birefringent-polarization interference, into which we newly insert a zeroth-order quarter-wave plate (QWP). The modified MC-FTS allows us to measure the wavelength dependence of the GP and thus that of the optical rotation angle due to the sample. In this paper, we describe the proposed approach and demonstrate proof-of-principle experiments.