Laser‐Induced Periodic Surface Crystalline Patterns on SrO–0.5Li ₂ O–4.5B ₂ O ₃ and BaO–0.5Na ₂ O–4.5B ₂ O ₃ Glasses and Optical Second Harmonic Generation

Transparent SrO–0.5Li ₂ O–4.5B ₂ O ₃ (SLBO) and BaO–0.5Na ₂ O–4.5B ₂ O ₃ (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 and differential thermal analysis 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 λ=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 μm periodicities.