Rapid Fabrication of Large-Area Concave Microlens Array on ZnSe

Integration of cross-scale milli/microlenses by ion beam etching and femtosecond laser modification

Integrated cross-scale milli/microlenses offer irreplaceable functions in modern integrated optics with the advantage of reducing the size of the optical system to millimeters or microns. However, the technologies for fabricating millimeter-scale lenses and microlenses are always incompatible, which makes the successful fabrication of cross-scale milli/microlenses with a controlled morphology challenging. Here, ion beam etching is proposed as a means to fabricate smooth millimeter-scale lenses on various hard materials. In addition, by combining femtosecond laser modification and ion beam etching, an integrated cross-scale concave milli/microlens (27,000 microlenses on a lens with a diameter of 2.5 mm) is demonstrated on fused silica, and can be used as the template for a compound eye. The results provide a new, to the best of our knowledge, route for the flexible fabrication of cross-scale optical components for modern integrated optical systems.

Phase-Type Fresnel Zone Plate with Multi-Wavelength Imaging Embedded in Fluoroaluminate Glass Fabricated via Ultraviolet Femtosecond Laser Lithography

Herein, we report a novel optical glass material, fluoroaluminate (AlF₃) glass, with excellent optical transmittance from ultraviolet to infrared wavelength ranges, which provides more options for application in optical devices. Based on its performance, the phase-type Fresnel zone plate (FZP) by ultraviolet femtosecond (fs) laser-inscribed lithography is achieved, which induces the refractive index change by fs-laser tailoring. The realization of ultraviolet fs-laser fabrication inside glass can benefit from the excellent optical performance of the AlF₃ glass. Compared with traditional surface-etching micro-optical elements, the phase-type FZP based on AlF₃ glass exhibits a clear and well-defined geometry and presents perfect environmental suitability without surface roughness problems. Additionally, optical focusing and multi-wavelength imaging can be easily obtained. Phase-type FZP embedded in AlF₃ glass has great potential applications in the imaging and focusing in glass-integrated photonics, especially for the ultraviolet wavelength range.