STUDY OF KTIOPO4 GRAY-TRACKING AT 1064-NM, 32-NM, AND 355-NM

Photochromic ''gray-track'' damage occurring during 1064 nm second-har monic generation (SHG) in KTiOPO4 is a significant limitation in many practical applications. Measurements of the evolution of gray-track da mage during SHG, along with measurements of the 355 nm radiation simul taneously produced by non-phase-matched sum-frequency generation, are described. Comparison of these measurements with the gray-tracking ind uced by exposure to a single wavelength indicates that for the conditi ons investigated here, the gray-tracking during 1064 nm SHG is depende nt only on the intensity of the 532 nm radiation. The dependence of th e induced absorption on the 532 nm intensity is nonlinear, having a th reshold of 80 MW/cm(2), and an approximately linear increase for inten sities above this threshold. (C) 1994 American Institute of Physics.