A Simple Way to Fabricate Close-Packed High Numerical Aperture Microlens Arrays

We present a developed femtosecond laser enhanced wet chemical etching method to fabricate close-packed and high numerical aperture (NA) microlens arrays (MLAs). Its ability to fabricate 100% fill factor MLAs with controllable NA is demonstrated and the maximum NA value of the lenses reaches to 0.47. This letter provides a simple and efficient way to achieve controllable and low cost optical elements. The close-packed and high-NA properties lead to excellent optical performance of the MLAs, which are highly required in high-resolution and high-signal-to-noise-ratio detections in micro-optical and integrated optical applications.