Combining effect in the multiple-beam pumped optical parametric amplifier

Summary form only given. Optical parametric amplifiers (OPAs) exhibit such attractive features as broad gain bandwidth and tunability, so they could be easily matched to virtually any existing sources of ultrashort pulses. The OPAs, in contrast to other nonlinear devices such as second harmonic or sum-frequency generators, allow the use of a multitude of pump beams with the condition that each of them satisfies the noncollinear phase-matching constraints with a single signal beam. This feature of OPAs has been demonstrated by simultaneous phase matching of two or three pump beams in order to narrow both spectral and spatial bandwidth of the emitted parametric superfluorescence.