GaN diffractive microlenses for UV micro-optics system

In this work, diffractive microlenses were fabricated in GaN-based material by using gravy-level mask and inductively coupled plasma etching technique. We also propose to insert the GaN/AlN anti-reflection thin films in the microlenses to enhance the ultraviolet/visible rejection ratio. Due to high transparency of GaN and AlN in UV, the microlenses can be potentially used in the UV micro-optics system such as solar-blind detection applications. In the design example of this work, the structure may enhance the ultraviolet/visible rejection to be 10².