OPTICAL MODULE USING DOUBLE-SIDED POLARIZING DIFFRACTIVE OPTICAL-ELEMENT FOR DIGITAL VERSATILE DISC DRIVES

Digital versatile discs (DVDs) promise to provide excellent multimedia storage for both entertainment and computer use. In this paper, we re port a newly designed optical module for use in DVD systems. It consis ts of a laser diode chip, a photodiode chip, a compound prism, and a d ouble-sided polarizing diffractive optical element (DOE). The double-s ided polarizing DOE provides high total light power efficiency (here 7 8%) that a DVD system requires because of its very small operational m argin. The developed optical module has dimensions 9.5 mm(W) x 4.2 mm( D) x 6.7 mm(H) and weighs 0.55 g. Its practicality has been demonstrat ed in successful DVD readout operations, and it is expected to provide the same compact, inexpensive drive that optical modules provide in c ompact disc (CD) systems.