Direct method for phase and amplitude determination of ultra-short light pulses

LIBERTUN, AR; SANCHEZ, GA; O.E. MARTÍNEZ

APPLIED PHYSICS B - LASERS AND OPTICS

SPRINGER

Lugar: Berlin; Año: 2002 vol. 74 p. 273 - 277

0946-2171

We present a new method for obtaining the phase of an ultra-short light pulse in the frequency domain. This technique is based on measuring the logarithmic derivative of the cross correlation of the pulse with a frequency-filtered version of it. It only requires sweeping the center frequency of the filter, while the time delay of the correlator is held fixed for measuring the group delay of the frequency components of the pulse. It is, to our knowledge, the first one-dimensional method to recover directly the phase information without resorting to a deconvolution or a procedure involving two Fourier transforms. Since it directly measures the delay operator we have called this technique direct group delay operator measurement. We present the theory, experimental results and a brief discussion of the best choice for the fixed setting of the time delay in order to improve the signal to noise ratio in this technique.