This book about structural designs and property characterizations for second-harmonic generation materials, second-order non-linear optical materials based on metal Iodates, selenites and tellurites, structure, growth, nonlinear optics and laser properties of RX3(BO3)4 (R=Y, Gd, La; X=Al, Sc)., the recent development of borate SF-conversion laser crystal, structure design and crystal growth of uv nonlinear borate materials, and cation effect in doped BBO and halogen anion effect in Pb2B5O9X (X– = I–, Br–, Cl–).