1. Semiconductor materials for telecommunications laser sources

There are two main semiconductor material systems for laser sources used in telecommunications: the system based on a gallium arsenide (GaAs) substrate and the one based on an indium phosphide (InP) substrate . The GaAs system covers the 0.8 to 1.3 μm band and the InP system the 1.3 to 1.6 μm band. These materials are grown using techniques such as molecular jet epitaxy or vapor phase epitaxy, which produce semiconductor crystals of excellent quality. These two material systems feature direct band gaps: a conduction band and a valence band whose extremities correspond to the same wave vector, separated by a band gap with energy E _g (gap energy...