Beta-Barium Borate Optical Parametric Oscillator

摘要

A Beta-Barium Borate Optical Parametric Oscillator (BBO OPO) has been constructedand shipped to the Army laboratory at White Sands. This OPO is a truly continuously tunable source with a very large spectral coverage. It is pumped at the third harmonic of Nd:YAG or 335 nm. The output is continuously tunable over the entire spectral range from 450 nm to 2.5 microns with relatively high efficiency. The tuning is completely computer controlled. The two-crystal configuration was needed to compensate for the walk-off in BBO. The intracavity pump beam steering mirrors are needed to reduce the change of uv damage of the resonator mirrors. The efficiency of the OPO is over 30%. The linewidth of the oscillator without using special line narrowing schemes is relatively large, however, there are special line narrowing schemes that can be employed to significantly reuse the linewidth at with some sacrifice in the threshold for oscillation and efficiencies. An alternative is to use Type II phase-matching, by which a line width on the order of an Angstrom can be maintained throughout the tuning range without additional line narrowing elements in the oscillator cavity.