Nonlinear optical properties of orthorhombic barium formate and magnesium barium fluoride

The nonlinear optical susceptibility tensors of barium formate (point group 222) and magnesium barium fluoride (point group mm 2) have been determined by the method of Maker fringes on the basis of a more rigorous theoretical treatment of second-harmonic generation of electromagnetic waves in plane-parallel plates of optically biaxial crystals. The measurements have been carried out in comparison with the KDP standard at awavelength of 1.064 μm (Nd: YAG). Both crystals possess nonlinear coefficients smaller than KDP (d ₃₆); they are phase matchable; magnesium barium fluoride exhibits a noncritical phase matching at a fundamental wavelenght of 1.04 μm.