Parametric excitation of light in the picosecond rang

An experimental and theoretical investigation is made of energy conversion in the three-photon parametric interaction of ultrashort light packets. Calculations are made both in the constant pump field approximation and for strong energy exchange between packets. A parametric two-stage oscillator generating ultrashort light pulses is described: it has an energy conversion efficiency of 12%, a line width of the output radiation of 4–5 cm^–1, and a high pulse repetition frequency (up to 25 Hz). A parametric small-signal gain of 10⁹–10¹⁰ can be achieved. The competition between stimulated Raman scattering (STRS) and stimulated parametric scattering, observed in a number of nonlinear crystals (α-HIO₃, KDP, LiIO₃), is discussed. The characteristics of picosecond optical parametric oscillators (OPO's) using α-HIO₃, KDP, LiIO₃, and LiNbO₃ crystals are given. An automatic measuring system incorporating amplitude analyzers, a data terminal, and a computer has been developed to investigate the energy and temporal characteristics.