THE NONLINEAR OPTICAL CHARACTERISTICS OF A LIB3O5 CRYSTAL

The nonlinear optical coefficients of lithium triborate LiB 3O5 (LBO) have been determined by the method of Maker fringes at λ=1.079 μm. It is found that these coefficients relative to d36 for potassium dihydrogen phosphate are d 31=∓2.51 (l±0.09), d3 2=±2.69 (l±0.12), d33=±0. 15 (l±0.10), d15=∓2.30 (l±0.22), and d24=±2.52 (l±0.20). The phase-matching conditions, effective second-harmonic generation (SHG) coefficients, walk-off angles, and acceptance angles for SHG at λ=1.079 μm are also investigated. The figures of merit of LBO in different cases are then compared with those of potassium dihydrogen phosphate (KDP), β-barium metaborate (BBO), and potassium titanyl phosphate (KTP) crystals. All these figures combined with the damage thresholds of the crystals show that an LBO crystal may operate better than KDP and BBO crystals for frequency conversions of a tightly focused Nd:YAlO3 (YAP) or Nd:Y3Al5O 12 (YAG) laser and also a dye laser.