| 摘要 |
PURPOSE:To control tracking and focusing even in case of variation in the wavelength of a laser, etc., by using a photodetector array as a photodetecting element. CONSTITUTION:An optical waveguide 2, a grating coupler 4 has a lens, a beam splitter 6, and a photodetector array 7 as photodetectors are arranged on a semiconductor substrate 1. The array 7 is formed of charged coupled devices (CCD) 100 in a linear array. Light from a semiconductor laser 3 becomes convergent light through a diffraction grating 4 and is converged on a disk 5 and its reflected light is converted on the array 7 through the beam splitter 6. At this time, the photodetector array 7 is used, so the center part of the convergence position is easily determined even in case of variation in the wavelength of the laser, and the tracking and focusing are controlled with its output signal. |
