Nonstationary nonlinear optical effects and ultrashort light pulse formation

A theory of nonstationary nonlinear wave phenomena occurring in the field of ultrashort high-intensity light pulses is developed (harmonic generation and parametric amplification stimulated Raman scattering). The main equations are given, the group velocity mismatch effects are studied, and special attention is paid to the high-conversion conditions. The possibilities of picosecond pulse narrowing on account of linear and nonlinear nonresonance parametric amplification and harmonic generation are studied in detail. The factors that determine the minimum light-pulse duration (dispersion broadening) are examined. A nonstationary theory of stimulated Raman scattering (SRS) is developed. Expressions for minimum pulse duration in forward and backward SRS are given. Reduction of Raman amplification with a picosecond pump is discussed.