3D micro-structuring by CW direct laser writing on PbO-Bi2O3-Ga2O3 glass

Direct laser writing was successfully performed into high refractive-index glasses with the composition of (PbO)(0.75-x)(Bi2O3)(x)(Ga2O3)(0.25) for x = 0-0.3, using focused continuous-wave laser beam emitting at 447 nm. The local changes in the material dimensions were induced by the illumination. Due to local overheating of the illuminated area microlenses and microcraters were formed. The overheating magnitude was calculated employing COMSOL-SW for illumination time 0.5 s and directly measured for the steady-state conditions. The microlens and microcrater formations with potential applications in optics were studied and the role of Bi2O3 content on their formation was investigated. The glasses with different Bi2O3 content had similar optical (penetration depth of laser), physical (density) and thermal (coefficient of thermal expansion) properties. On the contrary, the threshold power densities of the microlenses formation and microlines or their heights were significantly affected by the Bi2O3 presence. No changes in the chemical composition and structural arrangement were observed between non-illuminated materials and the objects (microlenses, microlines) formed by direct laser writing. However, the nanoindentation hardness of the objects was significantly lower compared to non illuminated glass. The threshold power density of microcraters formation does not depend on the chemical composition due to the similar residual roughness of the surfaces.

Automated summary

Direct laser writing was performed into high refractive-index glasses to create microlenses and microcraters. The presence of Bi2O3 significantly affected the threshold power densities of microlens and microcrater formation. The glasses with different Bi2O3 content had similar optical, physical, and thermal properties.