Optical device

Application Number: 00107084
Application Date: 2000.04.28
Publication Number: 1271933
Publication Date: 2000.11.01
Priority Information: 1999/4/28 JP 122709/99; 2000/4/24 JP 122877/00
International: G11B7/135;G02B27/42
Applicant(s) Name: Matsushita Electric (Electronics) Corp.
Inventor(s) Name: Takasuka Shoichi;Ishima Arakazu;Nakanishi Hideyuki
Patent Agency Code: 72001
Patent Agent: liu zongjie
Abstract An optical device includes a light-emitting element (1), a diffraction grating (2), a focussing member (5), a deflection member (3) and a photodetector (7). The diffraction grating has a first grating region and a second grating region, which have different diffraction efficiencies. The zero-order diffraction light in the first grating region is used as the main beam for reproducing the information signal, and the +1-order or -1-order diffraction light in the second grating regions is used as sub-beams for reproduction of the tracking error signal. Thus, the light amount of both the main beam and the sub-beams can be increased without increasing the light emission of the semiconductor laser element 1, and the S/N ratio of the main beam and the sub-beams can be enhanced.