Chia-Hung HOU, Ming-Hung LI¹, Chii-Chang CHEN, Jenq-Yang CHANG, Jinn-Kong SHEU¹, Gou-Chung CHI¹, Chuck WU², Wei-Tai CHENG³ and Jui-Hung YEH³

Institute of Optical Sciences, National Central University, 320 Jung-Li, Taiwan, R.O.C.
¹Department of Physics, National Central University, 320 Jung-Li, Taiwan, R.O.C.
²Canyon Materials Inc., 6665 Nancy Ridge Drive, San Diego, California 92121, U.S.A.
³Nano-Architect Research Corporation, 1F, No.5-2, Industry E. Rd. IX, Science-Based Industrial Park, Hsin-Chu, Taiwan, R.O.C.

(Received January 31, 2003; Accepted May 6, 2003)

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 10².

Key words: diffractive microlens, gray-level mask, GaN, AlN, solar-blind, band-pass filter