Single-mode semiconductor injection lasers for optical fiber communications

The present status of mode-stabilized semiconductor injection lasers emitting in the 0.8-0.9 and
1.1-1.6 \mu
m wavelength regions are described. The double-heterostructure GaAlAs/GaAs and InGaAsP/ InP crystals have been developed. Transverse-mode stabilization by means of gain guiding or index guiding is a key issue to realized high linearity, low noise operation. The mode-stabilized laser structures as well as the corresponding lasing characteristics are shown in detail. Longitudinal mode control is possible by grating feedback, but the fabrication technology is still immature. Reliability of the mode-stabilized lasers is also mentioned.