This paper first shows the basic idea about the mass production technology of AlGaAs laser diodes using Molecular Beam Epitaxy (MBE) technique. 'GaAs passivation technique' is the key to realize the stable mass production of self-aligned structure laser diodes. This paper, then, describes the designing concept and performance of a novel laser diode for short-haul optical data communications which we have recently developed. It has a high relaxation oscillation frequency, around 3 GHz, which is favorable to transmit data at a rate of 600 to 1200 Mbps. The lifetime (MTTF) is above 100,000 hours under 3 mW cw operation at 60 degree(s)C.