Convex silica microlens arrays processed by a Bessel beam femtosecond laser

As a key component of optical devices, the use of microlens arrays (MLAs) is becoming increasingly widespread, leading to deeper research on the materials and manufacturing processes of these microlens. The current microlens array processing methods have certain limitations in terms of stability and production efficiency. A method for fabricating convex silica microlens arrays using shaped femtosecond laser direct-writing is reported. The conversion of Gaussian beam to Bessel beam is induced by axicon (apex angle 176°, bottom angle 2°, refractive index 1.4533), and an anticircular beam intensity distribution with adjustable focal length is realized for precision ablation. The method employs horizontal and vertical removals with parameterized control of pulse energy (5-45 μJ) and scanning rate (0.4 mm/s), enabling single-step fabrication of 10 × 10 mm² MLAs within 1 h. The resultant MLAs exhibit exceptional optical performance, including broadband antireflection (2-4% reflectance at 200-1800 nm) and superhydrophobicity (150° contact angle at 20 μm periodicity). This technique addresses scalability limitations in hard transparent materials. It offers a streamlined solution for applications in beam shaping, optical communications, and harsh-environment imaging.