A HOLOGRAPHIC OPTICAL-ELEMENT FOR AN INTEGRATED OPTICAL HEAD

Diffraction efficiencies of a reflection-type blazed holographic optic al element (HOE) are analyzed and optimized for use in a totally integ rated optical head. The HOE, consisting of four-step phase levels, was fabricated by a double-etching process. By controlling each etching d epth, signal light power efficiency was maximized to 16% and the power ratio of noise components relative to signal light power was suppress ed to 21%. Diffraction efficiencies were made uniform over the entire HOE in oblique positioning by controlling the respective step widths o f the HOE.