New optical nonlinear crystallized glasses and YAG laser-induced crystalline dot formation in rare-earth bismuth borate system

New optical nonlinear transparent surface crystallized glasses have been successfully fabricated in the system of Ln2O3–Bi2O3–B2O3 (Ln=La, Sm, Gd). The second harmonic (SH) generation from the crystalline phases at the surface layers has been confirmed from Maker fringe measurements. It is suggested that the optical nonlinear crystals precipitated through the crystallization of Ln2O3–Bi2O3–B2O3 glasses would be new metastable BixLn1−xBO3 phases in which Bi3+ ions in BiBO3 are substituted by Ln3+ ions. The thickness of crystallized surface was approximately 5 μm and SH intensity was 0.02 compared with that of the Z-cut α-quartz with a thickness of 0.6 mm. In 12.5Sm2O3·30Bi2O3·57.5B2O3 glass, the crystalline dots with diameters of 5–65 μm are formed by the irradiation of CW YAG laser with a wavelength of 1064 nm (at 0.6 and 0.7 W, for 1–240 s), and it is found that these crystalline dots generate optical SH waves. This is the first finding on optical nonlinear crystalline dot formation by YAG laser irradiation in bismuth-containing glasses.