NONLINEAR PHASE CHARACTERISTICS OF THE DISPERSION INTERFEROMETER AT HIGH-INTENSITY PULSES

The dependences of the second harmonic (SH) intensity output by the di spersion interferometer (DI) upon the relative phase of the SH and fun damental waves theta(0) (called phase characteristics) are studied bot h experimentally and theoretically. It has been found that high irradi ance (when self-action effects are not negligible) makes the phase cha racteristics differ from the cosine type which is usual for linear int erferometry. In the case of high power pulsed radiation, a strong depe ndence of the SH pulse shape on theta(0) was observed. The evolution o f the SH pulse shape in the DI output registered as theta(0) varies is checked against the numeric simulation data. By measuring the nonline ar phase characteristics of the DI, the main influence of the slow (re sponse time of approximate to 1 ns) cubic nonlinearity on the frequenc y doubling of nanosecond pulses is determined for the employed KTP cry stals.