Birth of Single-Mode Diode Laser at Minimal Loss Band

There were two possibilities, namely GaInAsP/InP or AlGaAsSb/GaSb, to create a semiconductor laser operating at possible minimal loss band of silica fiber, as suggested by Donald Keck to be around $1.4-1.7\upmu\mathrm{m}$, in 1973. There was no rigorous reason for their selection, however the former was dare chosen after pointless argument, considering its higher melting temperature. In the early 1979, the minimal loss wavelength was found to be $1.55\upmu\mathrm{m}$ and occasionally, in that summer, the RT-CW operations at this targeted band were achieved by overcoming the barrier of anti-melt back. As extensions, the phase-shift distributed feedback laser was achieved its realization, and the electro-tunable laser was demonstrated, in 1983.