Single‐Shot Laser Additive Manufacturing of High Fill‐Factor Microlens Arrays

Abstract High fill‐factor microlens arrays (MLA) are key for improving photon collection efficiency in light‐sensitive devices. Although several techniques are now capable of producing high‐quality MLA, they can be limited in fill‐factor, precision, the range of suitable substrates, or the possibility to generate arbitrary arrays. Here, a novel additive direct‐write method for rapid and customized fabrication of high fill‐factor MLA over a variety of substrates is demonstrated. This approach uses a single laser pulse to delaminate and catapult a polymeric microdisc from a film onto a substrate of interest. Following a thermal reflow process, the printed disc can be converted into a planoconvex microlens offering excellent sphericity and high smoothness (R_RMS < 40 Å). Importantly, the transfer of solid microdiscs enables fill‐factors close to 100%, not achievable with standard direct‐write methods such as inkjet printing or microdispensing. Arbitrary generation of MLA over flexible and curved surfaces, with microlenses presenting a curvature ranging from 20 to 240 µm and diffraction‐limited performance, is demonstrated. The ease of implementation and versatility of the approach, combined with its potential parallelization, paves the way for the high‐throughput fabrication of tailored MLA directly on top of functional devices.