Optical device, optical semiconductor device, and optical information processor comprising them

An optical element comprising:

• a first optical element that is provided on one surface of a transparent member and that includes first and second diffraction gratings;
• and
• a second optical element that is provided on the other surface of the transparent member and that divides a reflected light beam into light beams in different focused states,
• wherein the first and second diffraction gratings are juxtaposed in a first direction, and gratings of the first diffraction grating are arranged in a direction different from the first direction.

(amended) An optical information processing device comprising:

• a laser element;
• an emitted beam dividing portion for dividing an emitted light beam from the laser element into a plurality of light beams;
• an optical system for guiding the light beams obtained by the division by the emitted beam dividing portion to an information recording medium;
• a reflected beam dividing portion for dividing a reflected light beam from the information recording medium into light beams in different focused states;
• servo-signal-detecting photodetector elements for receiving the reflected light beams obtained by the division by the reflected beam dividing portion in a defocused state;
• a first diffraction grating that is provided in the emitted beam dividing portion and that diffracts the reflected light beam having passed through the reflected beam dividing portion;
• and
• a signal-detecting photodetector element for receiving reflected light beams having been subjected to the diffraction by the first diffraction grating.