Gallium nitride diffractive microlenses using in ultraviolet micro-optics system

In this work, diffractive microlenses were fabricated in GaN using a gray-level mask and inductively coupled plasma etching technique. We also propose to insert the GaN/AlN band- pass filter in the microlenses to enhance the ultraviolet/visible rejection ratio. Due to high transparency of GaN and AlN in UV, the microlenses can potentially be used in a UV micro-optics system such as for solar-blind detection. In the design example of this work, the structure may enhance the ultaviolet/visible rejection to 10(2).