Measurement of coherent polarisation relaxation times in condensed media using femtosecond interferometric spectroscopy

An ultrafast spectrometer with a temporal resolution of 20 fs for studying the polarisation wave interference in condensed matter upon resonance excitation by femtosecond laser pulses is described. The transverse relaxation times T₂ < 20 and 50 fs are measured in optical media with considerably different inhomogeneous broadenings.