Laser direct writing into PbO-Ga2O3 glassy system: Parameters influencing microlenses formation

[Display omitted] •CW laser direct writing into heavy metal oxide glasses (PbO)x(Ga2O3)1−x.•the role of several parameters on the microlenses formation were investigated.•applied diagnostics SEM, DHM, AFM, Nanoindentation, µRaman spectroscopy.•local light-induced overheating suggested as a dominant effect for expansion. New microlenses with potential applications in optics on the surface of the various glasses of the (PbO)x(Ga2O3)1−x system (x = 0.698–0.789) were created. The role of several parameters (chemical composition, surface roughness and exposition conditions) on the microlenses formation was investigated. The most promising composition is (PbO)0.747(Ga2O3)0.253 possessing metagallates structure, which is the most thermally stable and thus this glass has the lowest value of the fragility factor. This is related to the highest threshold value of the laser power density for the microlenses formation. The highest microlenses were created for this composition. The Root Mean Square characterizing the surface roughness should be ≈ 2.8 nm. An increase of exposition time and the used laser power density led to the microlenses height rose. The threshold value of the microlenses formation decreased significantly with the increased exposition time. Certain properties of microlenses and non-illuminated surroundings of microlenses were compared. There were no structural and chemical composition changes observed using the Raman Spectroscopy and EDX analysis, respectively. The Force Spectroscopy mode and the Nanoindentation found a decrease in the created microlens stiffness and hardness by 8 and 10%, respectively. The thermal expansion is suggested as the most likely mechanism of microlenses formation.