Optical parametric amplifiers: A discrete dynamical model of singly resonant operation leading to a novel approach to the design of systems for high-efficiency amplification

A simple plane-wave model of pulsed, singly resonant, optical-parametric-oscillator and optical-parametric-oscillator-amplifier operation leads to a description of such systems in terms of a discrete dynamical system. The theoretical limits on conversion efficiencies derivable from this model were explored. Analysis of the model for an optical parametric oscillator-amplifier (OPOA) indicates that the effect that backconversion has in limiting efficiency can be avoided if one precisely shapes the time profile of the pump pulse and combines it with an OPOA that is Q switched. For a case of type I phase matching with beta-barium borate with a specific pump profile and a 65-mJ input pulse, under the assumption of small absorption, the following are demonstrated: (1) the theoretical possibility of amplification to a few joules at quantum efficiencies higher than 90% and (2) the possibility of amplification to approximately 1J at an energy efficiency near 45% in a configuration satisfying realistic stress constraints. Pulse widths are in the nanosecond range, and spot sizes are in the millimeter range. Issues of implementation are discussed.