Hiroaki Kudo

Operation of 780 nm AlGaAs Distributed Feedback Lasers at 100°C with Low-Loss Waveguide Structure

Stable single-mode operation of 780 nm wavelength was obtained with AlGaAs distributed feedback (DFB) lasers grown by metal organic chemical vapor deposition (MOCVD) and liquid-phase epitaxy (LPE). To achieve both high-temperature and broad-range temperature single-mode operation, we propose a new type of low-loss waveguide (LLG) structure and the use of trapezoid-shaped third-order corrugation. The devices showed a wide range of operating temperature up to 100 o C, output power of 10 mW cw operation even at 100 o C, high side-mode suppression ratio of more than 30 dB, and wide fixed single-mode operation temperature range of more than 90 degrees. We have confirmed that these AlGaAs DFB lasers are applicable to holographic laser beam printers or scanners

Integrated optic disc pickup

The present status of waveguide-type integrated-optic disc pickups are reviewed. The authors have proposed and fabricated several types, and have demonstrated their fundamental functions. For the ROM pickup, they successfully reduced the focused spot to a diameter that is slightly larger than the diffraction-limited value, and confirmed capability of the focusing/tracking error signal detection. The pickup was extended to that for magneto-optical (MO) disc system, and the MO pickup was found experimentally to detect a polarization rotation as small as one contained in the signal beam reflected from MO medium. The pickup for parallel-data cards was also fabricated with photodiode array, and seven-track parallel readout was demonstrated. It was found by theoretical analysis that the waveguide-FGC combined type pickup has the possibility of super-resolution readout.