LASER ULTRASHORT-PULSE SPECTROSCOPY OF TH E ORDER PARAMETERS OF HYDROGEN-BONDED FERROELECTRICS

The change in the duration of an ultrashort laser pulse during its pas sage through a single crystal of a hydrogen-bonded ferroelectric is de termined as a function of the temperature of this crystal and, consequ ently, of the order parameter It is shown that, depending on this temp erature, a pulse may become shorter or longer inside the crystal. This makes it possible to use such ferroelectrics in reducing the duration of ultrashort laser pulses. The temperature at which an increase in t he pulse duration changes to a reduction is determined. The dependence of this temperature on the internal parameters of a ferroelectric is found.