Optical pickup

An optical pickup for reading information recorded on an optical information recording medium by irradiating the medium with a laser beam, comprising:

• a laser source unit which houses a plurality of laser emitting devices for emitting a plurality of laser beams mutually differing in wavelength;
• an objective lens which forms, by converging a laser beam emitted from the laser source unit, a converged light spot on an information recording surface of the optical information recoding medium;
• an optical waveguide device on which a laser beam reflected from the information recording surface where the converged light spot is formed is incident and which emits a zeroth-order beam and positive and negative first-order diffracted beams generated from the reflected laser beam;
• and
• a photodetector having a plurality of light receiving surfaces on each of which the zeroth-order beam or positive or negative first-order diffracted beam generated, by the optical waveguide device, from the reflected laser beam is incident and each of which outputs a light detection signal corresponding to an optical intensity of the beam incident thereon;
• wherein the optical waveguide device has at least three divided regions divided by at least two division lines extending, on the optical waveguide device, approximately in parallel with a direction along which a recording track of the optical information recording medium extends, the divided regions each causing a zeroth-order beam out of the reflected laser beam to be incident on one, on which none of the positive and negative first-order diffracted beams is incident, of the light receiving surfaces of the photodetector.