Dynamic data compression algorithms in speech coding

Abstract

The single transverse mode AlGaAs/GaAs laser array with pulsed peak power up to 100 mW has been fabricated successfully. The ridge waveguide laser structure was chosen since it needs only one step liquid phase epitaxy which greatly improves the yield. The ridge waveguide was formed by etching the top p‐type cladding layer through a 4 μm to 5 μm mask down to the neighborhood of the active layer to form a lateral refraction index difference. It is found that when the spacing between ridge is 5 μm, individual lasers are not coupled, and the far field pattern displays a diverged single lobe with a half width of 18° similar to that of a single laser. When an end broad area region is inserted, however, the laser array starts to couple and forms a narrow two‐lobe beam with a half width of 5°. The near‐field pattern can be used to analyze the coupling condition.