MP-B5 GaAlAs visible laser arrays

A GaAlAs visible laser array, where nine lasers which can be operated independently are closely spaced, is demonstrated. Recently, modestabilized GaAlAs lasers have been realized in the 0.7-pm wavelength region using CSP structure.’ The reliability of GaAlAs visible lasers has also been fairly improved.’ And now, the main interests have been concentrated on integration capability of the visible lasers with special emphasis on the uniformity of the lasing characteristics and interaction between individual lasers. Four layers-n-Gao~4A10~6Aslayer (Te doped);n-Gal -,Al,As active layer ( x = 0.15-0.2, undoped, -0.1 pm thick); pGao,,A1,.,As layer (Zn doped); and n-GaAs layer (Sn doped)were grown successively on a grooved n-GaAs substrate by liquid phase epitaxy. In the array chip, nine modestabilized CSP lasers with a stripe width of 7 pm are arranged with a separation of 100 pm. Each laser is isolated electrically with etched grooves. The array chip was face-down bonded on a 2 mm X 3 mm submount with diffusion-isolated electrodes. The laser operated continuously at an average threshold current of 86 mA with an average lasing wavelength of 740 nm at room temperature. The scattering of the threshold current and wavelengths in the array chip are within +5 mA and +2 nm, respectively, indicating excellent local uniformity of the epitaxial layers in the array size. Each laser operated without kinks up to a light output power of 5 mW/facet. Dynamic behavior of lasers in the array showed no optical and electrical interactions between lasers. The thermal resistances of the array were 30 deg/W and 80 deg/W for a singleand multi-laser operation, respectively; and there exists strong thermal interaction between lasers. However, the time constant of the thermal interaction was as long as 2-3 ms. Therefore, each laser in the array operated independently in the modulation frequency range above 1 MHz. The GaAlAs visible laser array is confirmed to be an important and useful device as multibeam laser source for optical processing systems.