Laser Induced Periodic Surface Crystalline Patterns on SrO-0.5Li2O-4.5B2O3 and BaO-0.5Na2O-4.5B2O3 Glasses and Optical Second Harmonic Generation

Transparent SrO-0.5Li2O-4.5B2O3 (SLBO) and BaO-0.5Na2O-4.5B2O3 (BNBO) glasses were fabricated via the conventional melt-quenching technique. The amorphous and glassy characteristics of the as-quenched samples were respectively confirmed by X-ray powder diffraction (XRD) and Differential Thermal Analysis (DTA) studies. Optically clear SLBO and BNBO glass nano/microcrystal composites were obtained by heat-treating the as-quenched glasses slightly above their respective glass transition temperatures. These glass nano/microcrystal composites exhibited second harmonic signals in transmission mode when exposed to infrared laser beam at \lambda =1064 nm. Interestingly second-harmonic waves were found to undergo optical diffraction and was attributed to the presence of self-organized microcrystalline patterns associated with 0.5-2\mu m periodicities.