Beam patterns in an optical parametric oscillator set-up employing walk-off compensating beta barium borate crystals

Abstract

This paper describes the investigation of an optical parametric oscillator (OPO) set-up based on two beta barium borate (BBO) crystals, where the interplay between the crystal orientations, cut angles and air dispersion substantially influenced the OPO performance, and especially the angular spectrum of the output beam. Theory suggests that if two BBO crystals are used in this type of design, they should be of different cuts. This paper aims to provide an experimental manifestation of this fact. Furthermore, it has been shown that air dispersion produces similar effects and should be taken into account. An x-ray crystallographic indexing of the crystals was performed as an independent test of the above conclusions.

Highly efficient H-β Fraunhofer line optical parametric oscillator pumped by a single-frequency 355 nm laser

“…The effective nonlinear coefficient (d eff ) of BBO is 2.06 pm/V, and the walk-off angle of the pump light is 70.2 mrad. The BBO crystals were cross symmetrically placed relative to the pump beam axis to compensate for the walk-off effect [19] . The aperture of the BBO bulks was 8 mm × 8 mm.…”