Time-domain measurement of optical activity by an ultrastable common-path interferometer

Abstract

We introduce a novel configuration for the broadband measurement of the optical activity of molecules, combining time-domain detection with heterodyne amplification. A birefringent common-path polarization-division interferometer creates two phase-locked replicas of the input light with orthogonal polarization. The more intense replica interacts with the sample, producing a chiral free-induction decay field, which interferes with the other replica, acting as a time-delayed phase-coherent local oscillator. By recording the delay-dependent interferogram, we obtain by a Fourier transform both the circular dichroism and circular birefringence spectra. Our compact, low-cost setup accepts ultrashort light pulses, making it suitable for measurement of transient optical activity.

Time resolved transient circular dichroism spectroscopy using synchrotron natural polarization

“…They used a combination of a Pockels cell and a light continuum generator to obtain a pulsed white light source alternately circularly right and left polarized. Recently, Preda and co-workers have introduced a new experimental arrangement based on the combination of time-domain detection and heterodyne amplification 11 . This approach allows time-resolved optical activity measurements.…”

A Real-Time Automated System for Dual-Aperture Common-Path Interferometer Phase-Shifting

“…Typically, in sensing DACPI applications, the determination of φ(x, y) allows the estimation of a physical, chemical or biological quantity. Here, a measurable quantity from a transparent object placed at the probe arm can be related to the phase difference between the light beams from both arms [15,[29][30][31]. For practical applications, it is convenient to obtain an immediate value of φ(x, y) to achieve real-time monitoring of the measured quantity, which also allows fast and precise calibration of the system.…”

Instrumentation for Vibrational Circular Dichroism Spectroscopy: Method Comparison and Newer Developments

“…To date this has not developed further due to sensitivity limitations. A new method of polarization division interferometry with a common path has recently been developed by Polli and co-workers that uses a sliding wedge to create a variable delay between two polarizations that then interfere to give an elliptically polarized beam [ 129 ]. This approach has been shown to duplicate conventional VCD measurements as well as measure circular birefringence and to also operate with femtosec pulses opening the possibility of fast dynamic VCD measurements.…”