KxRb1−xTiOPO4: A new nonlinear optical material

KxRb1−xTiOPO4, a new nonlinear optical material with coefficients comparable to BaNa2Nb5O15, has been prepared as optically perfect single crystals which are transparent from 350 to 4500 nm. We have shown that the material is phase matchable over its entire transparency range and that 1060-nm radiation can be doubled with minimal beam walk-off. The material is free from optical damage for power densities at least as large as 150 MW/cm2. Also, it is chemically stable and easily polished.