| 摘要 |
PURPOSE:To increase the light utilization efficiency in an integrated type optical pickup. CONSTITUTION:A grating coupler 6a is provided on an optical waveguide 7a. This grating coupler is constituted as a double diffraction grating formed by superposing a diffraction grating which couples only TE waves to incoming waves and converges them in the vicinity of a detector 8c and a diffraction grating which couples only TM waves and converges them in the vicinity of the boundary between detectors 8a and 8b and the boundary of the detectors 8d and 8e. A change in polarizing direction can be detected by using difference signals between the output of the detector 8c and the outputs of the detectors 8a, 8b, 8d, and 8e. The utilization efficiency of light can be increased as compared with an integrated type optical pickup for a magnetic disk which is conventionally considered, and consequently the C/N can be increased. |
