GaN-based micro-optics will combine with future blue and UV VCSELs

In the quest for compactness of hardware, researchers at National Central University (Jung-Li, Taiwan) and Chang Gung University (Tao-Yuan, Taiwan) have developed gallium nitride (GaN)-based stacked micro-optical systems that could further shrink optical-disk pickup heads from the already small size they are today.

May 1st, 2006

In the quest for compactness of hardware, researchers at National Central University (Jung-Li, Taiwan) and Chang Gung University (Tao-Yuan, Taiwan) have developed gallium nitride (GaN)-based stacked micro-optical systems that could further shrink optical-disk pickup heads from the already small size they are today. With the development of additional components, these stacked optical systems could be used for microprojection displays or micromonochromators. The researchers have already fabricated a system that includes a vertical-cavity surface-emitting laser (VCSEL), a spatial filter, a GaN microlens, and a GaN membrane grating.

Because GaN transmits well in the blue and UV, it is well suited for Blu-ray and HD-DVD optics. Because no blue or UV VCSEL yet exists, though, a VCSEL emitting at 980 nm was used for the experiment. A spatial filter and six spacers were formed photolithographically from silicon; a separate gray-level photolithographic process was used to create the grating and diffractive lens, which were spaced 3.7 mm away from the VCSEL. While the far-field diffracted patterns were not well formed, better fabrication techniques will improve transmission and overall quality. Contact Chia-Hung Hou at chhou@ios.ncu.edu.tw.

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