4. Microsecond to nanosecond operation

4.1 Optical parametric generators

In the microsecond regime, as in the continuous regime, the conversion efficiency of an OPG is generally limited by the low peak power of the pump laser available.

In the nanosecond regime, peak pump powers are sufficient to generate potentially intense radiation (possible conversion efficiencies of several tens of percent).

In this case, to avoid optical parametric oscillation between the crystal faces, a very good anti-reflective coating must be applied to the faces, and/or a bevel cut of one of the faces may be considered.

With such high conversion efficiencies, the gain is saturated for certain spatial components of the emitted radiation, which can result in beams of degraded...