Fabrication of znse microlens array for a wide infrared spectral region

The infrared (IR) is a strategically important band for numerous applications from environment to biochemical imaging. Here a novel IR optical component integrates more than 2000 plano-concave microlenses on the zinc selenide (ZnSe) surface within a footprint of 5\times 5 mm2 is proposed by a combined method of femtosecond laser direct irradiation and chemical wet etching. Microlenses with diameter from 15 to 30~\mu \text{m} are realized by controlling the laser power and etching time. The uniform close-packed microlens arrays (MLAs) with minimized volume and high transparency at wavelengths of 0.76\sim 22\mu \text{m} are realized. The MLAs have relatively good topography and surface quality. The modulation transfer function (MTF), imaging test and optical-focusing test confirm the outstanding IR imaging. Owing to the merits of micro-size, light weight, high integration and excellent IR imaging performance, the as-fabricated MLA is promising in cutting-edge mid-IR and far-IR application, such as IR sensing system, imaging system, and so on.