Influence of optical inhomogeneity on the parametric amplification of picosecond light pulses in lithium niobate crystals

A theoretical and experimental investigation is reported of the influence of a longitudinal optical inhomogeneity of a lithium niobate crystal on the parametric amplification of picosecond light pulses. It is shown that an increase in the gain reduces the influence of the inhomogeneity on the effective length of the crystal. This makes it possible to use longer crystals in picosecond optical parametric oscillators, in spite of the fact that the inhomogeneity of such crystals makes them unsuitable for nanosecond parametric oscillators.