Integrated-Optic Disc Pickup Devices Using Waveguide Holographic Components

Abstract
The authors' work is reviewed on implementation of integrated-optic disc pickup devices using waveguides and holographic components. The integrated-optic disc pickup (IODPU) is constructed by integrating a focusing grating coupler (FGC), a grating beam splitter and photodiodes in a waveguide on Si, and is capable of detecting readout signal and tracking/ focusing error signals. The gratings are fabricated by computer-controlled electron-beam writing and reactive ion etching. Integration of detection optics for magneto-optical disc pickup is also presented. The device uses a trifocal-FGC, which serves as a polarization splitter based on waveguide mode dispersion, and performs differential detection of MO read-out signal. The design considerations, fabrication processes and experimental works are presented including the most recent results. Although the performances obtained so far are not sufficient for practical application, the elementary functions have been successfully demonstrated.