AbstractOptical‐disk pickup heads have been constructed with microoptics. Great improvement in producibility and reduction of weight and size are expected by replacing the pickup head with integrated optics. Such an integrated optic device can be constructed by a focusing grating coupler (FGC) which focuses an optical guided wave onto a point in space. This paper describes the theoretical and experimental examinations of the fundamental characteristics of the FGC for the integrated optical disk pickup device. The theoretical analyses show the feasibility of an FGC having a focus spot width larger than the diffraction‐limited value only by 3 percent and the efficiency of 60 percent, by optimizing the device parameters. The analyses of the imaging of the optical system show that the tracking error and the focusing error of a disk can be detected as the displacement of the focal point of the back‐coupled optical guided wave. By fabricating FGCs by an electron‐beam etch method, the focus spot widths were measured to be 3 μm for the laser diode and 1.4 μm for the He‐Ne laser, while the diffraction‐limited values are 1.4 μm and 1.1 μm, respectively, and the imaging relation was confirmed. The efficiency was measured to be 40%. It is necessary for the pickup operation and was confirmed experimentally that the reflected light from the focal plane is coupled back into the waveguide