Nanosecond optical parametric oscillators

The main characteristics of nanosecond OPOs an presented: nonlinear crystal s, tunability ranges, output energies, phase-matching conditions. A semiana lytical model and a completely numerical model are described. They point ou t the importance of the complex intensity distribution that appears in the transverse planes of the output pulses. Techniques to improve the spectral and spatial quality of the output beams such as intracavity Fabry-Perot fil ters or unstable cavity are detailed. Finally a modelisation and experiment al results about intracavity OPO are presented. (C) 2000 Academie des scien ces/Editions scientifiques ct medicales Elsevier SAS.