An optical pickup comprises a substrate, an optical waveguide formed on the substrate, a semiconductor laser attached to the optical waveguide, and a grating formed on the optical waveguide and converging a waveguide light in the optical waveguide to an optical recording medium. On the substrate, there...http://www.google.co.uk/patents/US5233595?utm_source=gb-gplus-sharePatent US5233595 - Optical pickup including waveguide light intensity detection means for controlling a position/intensity of a semiconductor laser
