Lasers and amplifiers for networks

Summary form only given. Recent progress on semiconductor laser diodes (LDs) and optical amplifiers is summarised from the viewpoint of optical network system applications. Manufacturing techniques for InGaAsP/InP have been progressing rapidly. Recent efforts have been focused on high-speed response, narrow spectral linewidth, wavelength tuning, and monolithic integration for optical devices. Larger than 20-GHz bandwidth and 18-Gb/s random pulse modulation have been reported. A tunable range of 100 AA (1.25 THz) has been reported for a three-section distributed Bragg reflector (DBR) LD. Multielectrode distributed feedback (DFB) LDs offer the possibility of very fast switching although the tuning range is limited to about 10 A. Er-doped fiber amplifiers seem to be at a more practical stage than LD amplifiers. However, LD amplifiers have a very wide gain bandwidth, which is suitable for simultaneous amplification of WDM/FDM signals. Multi-quantum-well LD amplifiers with about 20-dBm saturation output have been reported.<>