Fourier Transform Spectroscopic Measurement of the Kerr Effect

Abstract

A Fourier Transform spectroscopic technique for the measurement of frequency and electric field department birefringence (Kerr effect) has been developed. The Kerr effect alters the polarization of light due to the anisotropy of the medium. In these studies, the anisotropy of the propagation medium is the polarization dependent $\Delta M=0$ vs. $\Delta M=\pm 1$ (parallel vs.perpendicular polarization) transitions of polar molecules in an electric field. In the past, Kerr effect spectra have been recorded by the measurement of transmission through crossed polarizers. Because the polarization anisotropy induced by the electric field in the medium can be extremely small, the use of a photoelastic modulator allows for better signal collection through lock-in amplification. The $\tilde{A} {^{1}A_{2}} \leftarrow \tilde{X}{^{1}A_{1}}$ UV transition of formaldehyde was selected as a benchmark study. The spectra collected by our Fourier Transform polarization modulation method will be compared to previous $work^{1}$.