Intro

Calculations

The home-made simulation program is written in Python and based on 4x4 transfer matrix method. The duration and shape of incoming laser pulse can be adjusted. Also one can define the structure, which response is to be studied, by setting each layer' thickness, real and imaginary parts of material permittivity and gyration vector magnitude. Using Fourier transform, input pulse is presented as a wave packet in the frequency domain. For each wavelength the program calculates electric field transmitted through the layered structure in the basis of circular polarizations as it is natural for gyrotropic media. In the end, all components are gathered together and after inverse transform one can get time development of pulse intensity, phase and Faraday rotation.

Experiment

Experimental set-up consists of two main parts: magneto-optical one and autocorrelation one. Magneto-optical part is designed for precise measurements of Faraday rotation in sample and for this purpose includes photoelastic modulator (Hinds Instruments Inc.).

Autocorrelation part of the set-up divides the input pulse into two identical replicas, and then one of them goes through a variable delay line. Afterwards both pulse replicas are set parallel and then focused into the same spot of the nonlinear crystal of BBO. As a result, second harmonic is produced along the bisector of the angle between fundamental pulses. The measured signal is the intensity of second harmonic at the dc and photoelastic modulator frequency vs. time delay.