U. Chatterjee et al., EFFICIENT TUNABLE NEAR-INFRARED SOURCE BY DIFFERENCE-FREQUENCY MIXINGIN POTASSIUM TITANYL PHOSPHATE CRYSTAL, Journal of physics. D, Applied physics, 28(2), 1995, pp. 275-279
Tunable near infrared (NIR) radiation from 1200 to 1800 nm is generate
d by non-collinear difference frequency mixing of Nd:YAG and its secon
d harmonic pumped dye laser radiations in a flux grown KTP crystal. In
the process, the 'retreation phenomena' in the phase matching curve f
or difference frequency mixing in KTP is observed for the first time.