Efficient, single-axial mode oscillation of a beta barium borate optical parametric oscillator pumped by an excimer laser

Intracavity etalons have been used to obtain single axial mode oscillation of a beta barium borate optical parametric oscillator pumped at 308 nm by a XeCl excimer laser. Two high finesse etalons were sufficient to select a single axial mode of the resonant signal wave over a tuning range 400–560 nm with the increase in oscillation threshold due to etalon insertion being kept below 1.5 times. Addition of a grating enabled single axial mode oscillation to be maintained out to degeneracy (616 nm).