Growth and non-linear optical properties of lithium triborate crystals

The Li 2 O-B 2 O 3 -MoO 3 ternary system was investigated to determine the region of growth of lithium triborate Li 2 O.3B 2 O 3 (LBO) crystals with good optical properties. The top-seeded solution growth method, the method of spontaneous crystallisation and solid-state reactions were used in this investigation. The phases were defined by the method of X-ray power diffraction. The data obtained in these experiments made it possible to choose the region of compositions of solutions in the Li 2 O-B 2 O 3 -MoO 3 system for the successful growth of LBO single crystals. LBO single crystals, up to 100 x 82 x 45 mm 3 in size and 290 g in weight, were grown free of cracks, bubbles and inclusions. These single crystals were of high optical quality: wavefront distortion (fringe per mm for λ = 0.633 μm) was lower than 1/150, absorption losses (0.25 μm < λ < 2.5 μm) in the resultant LBO single crystals were lower than 0.005 cm -1 , and the damage threshold at = 1.06 μm, τ = 10 ns in the LBO single crystals was more than 10.0 GW/cm 2 . High performance non-linear optical elements of various optical orientations, up to 20 x 20 x 20 mm 3 in size, were fabricated on our LBO crystals.