We have developed GdxY1-xCa_4O_3(BO_3)_3(Gd_xY_<1-x>COB) crystal in order to control optical birefringence. Gd_xY_<1-x>COB crystals with uniform composition. Furthermore Gd_<0.24>Y_<0.76>Ca_4O(BO_3)_3 crystal is possible to generate (θ,φ)=(90°,90°) phase matched third harmonic of 1064nm light.
