Spectral noncritically phase-matched near-infrared generation by difference frequency mixing in lithium triborate

Retracing behavior of phase matching has been observed in the generation of infrared radiation (1.25–1.85 μm) by both type-I angle-tuned and temperature-tuned difference frequency mixing of a Nd:YAG laser (1064 nm) with its second-harmonic pumped dye laser (570–675 nm) in lithium triborate crystal. Large spectral acceptance of 49 nm at spectral noncritical phase-matching point and angular acceptance of 4.0° at angular noncritical phase-matching point has been obtained.