Integrated detection optics for magnetooptical (MO) disk pickup are proposed. The pickup consists of a waveguids device, external lenses, a beam splitter and a laser diode. The detection optics is constructed by integrating a trifocal focusing grating coupler and five photodiode elements in a glass-film waveguide on a Si substrate. The design considerations and fabrication are described, and experimental results are reported. The wavelength bandwidth of the devices are discussed in relation to the wavelength instability of laser diode. Although the obtained performances are not sufficient for practical application, the elementary functions, i.e., MO signal readout, focusing error detection and stabilization by multimode LD, were successfully demonstrated in the simulation experiments.

A new wavelength-selective optical modulator was proposed and discussed. The modulator consists of three kinds of distributed Bragg reflectors (DBRs) integrated in a single straight waveguide. The waveguide can guide TE$_0$ and TE$_1$ modes, and an in-line Michelson interferometer is constructed by the three DBRs. An operation-wavelength wave among incident wavelength-division-multiplexed TE$_1$ guided waves is split into TE$_0$ and TE$_1$ guided waves by one of DBRs, and combined by the same DBR to be TE$_0$ output wave with interference after one of waves is phase-modulated. A modulator using an electro-optic (EO) polymer is designed, and the static performance was predicted theoretically. An operation principle was confirmed experimentally by a prototype device utilizing a thermo-optic effect instead of the EO effect.