Accuracy of measuring the instantaneous spectral intensity of femtosecond pulses

The topical problem of measuring the time dependences of the femtosecond pulse instantaneous spectral intensity using the Fourier-Gabor transformation is considered. Computer simulation shows that the width of the window in which the spectral intensity is constant and the number of these windows “along” the pulse where the spectral intensity does not depend on the window width may vary in wide limits. The width of the window and its travel along the signal are optimized without sacrifice of the measurement accuracy. The efficiency of the method is demonstrated in a physical experiment with terahertz pulses acting on L-cystine amino acid.