Abstract
Two optical devices with nano-scale subwavelength structures have been fabricated by using nanoimprint lithography (NIL). (1) Wire grid polarizer (WGP) is one of key optical components for projection displays with liquid crystal micro-display. Although WGP with 140 nm pitch is commercially available now, it still poses a problem with low extinction ratio (ER) for blue color. Since the ER can be increased by reducing the pitch, fabrication of a WGP with 100 nm pitch was attempted by NIL. We successfully developed thermal nanoimprint and aluminum dry etching processes. Fabricated WGPs showed twice higher ER than 140 nm pitch one. (2) Photonic crystal (PC) structures on LED have been known to enhance the light extraction significantly. Although e-beam lithography has been used for the proof of principle, it is far from real production method. We applied thermal NIL to fabricate PC structures in p-GaN layer of green LED. To identify the PC effect, two structures were fabricated and compared. One structure makes the green light of 525 nm wavelength fall within the photonic band gap (PBG) while the other puts it outside of PBG. The former structure showed 9-fold increment of photoluminescence compared to LED without PC structures, while the latter showed only 6-fold increment
Published Version
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