Parametric optical oscillator with non-linear crystal

摘要

The optical cavity is defined by two reflectors (42, 44) and contains the crystal (32) which adapts the pumped beam (36) and a diffraction grating (30) which is centred so that the plane of dispersion is not orthogonal to the extraordinary plane of the crystal but may be essentially collinear. A zero order half-wave plate (28) turns the plane of polarisation of the resulting beam towards that of the extraordinary beam. The cavity may be centred so that the pump beam and the resultant beam are not collinear. One of the orders is the output and a tuned mirror (44) reflects back one other order. The crystal used may be a BBO crystal with the grating having a Littrow mounting.