Abstract

The focusing grating coupler (FGC) has been developed for application to optical data storage.¹ This device is of considerable interest for low-cost highly stable optical heads. Figure 1 shows an optical schematic of the device. A laser diode is optically coupled to a slab laser wave guide. The light in the slab propagates to the FGC where it leaves the slab and focuses to a point. After reflection from the surface of the optical recording media, the light returns to the FGC as a diverging beam. After a second diffraction from the FGC, the light again propagates in the slab -- this time in the reverse direction. A linear grating is used to diffract part of the return illumination into orders that focus to either side of the laser diode.

© 1987 Optical Society of America