One-stop direct laser writing of fused silica convex microlens arrays with high filling factor

While fused silica microlens arrays with high filling factor are essential for advanced optics, their precise fabrication is challenging due to complex geometry and poor machinability. This work proposes a fully direct laser writing based one-stop fabrication method for 100% filling factor convex microlens arrays, by integrating CO₂ laser-based in-situ coarse shaping and delicate polishing. Specifically, the coarse shaping enables precise formation of convex lens contour from planar substrates, through integrating a layered slicing strategy with layer thickness calibrated according to CO₂ laser ablation characteristics of fused silica. Subsequent delicate polishing eliminates microscale surface steps on lens surface via viscous flow and re-solidification mechanisms, achieving significant surface smoothening. The established synchronized experimental platform of direct laser writing enables CO₂ laser activation precisely coordinated with beam motion characteristics, and alternating unidirectional scanning paths are employed to maximizing the overlap between lenses for increasing filling factor. Finally, dimensionally controllable convex microlens arrays with high filling factor and high precision on large size fused silica are successfully fabricated, which exhibit considerable imaging performance and transmittance. The reported results demonstrate the feasibility of proposed methodology for realizing highly efficient and precision fabrication of fused silica microlens arrays with high filling factor.