Abstract

Although telecommunications have been the driving force of semiconductor laser research the main markets for semiconductor lasers are now in what once were spin-off applications, such as CD-players, laser printers etc. Tunable single frequency lasers have been developed for heterodyne and WDM fiberoptics communications systems, to a stage where they now are practical and useful devices. The availability of these lasers has opened up a wide variety of new applications. Two examples are gas sensing and distance/vibration measurements. Multisection DFB lasers can be timed typically 1-2 nm while maintaining a narrow linewidth. This, in combination with good FM properties, make them attractive in coherent communication. Another application is FMCW laser radar (Refs. 1,2). In this case the distance to a target is determined by a coherent technique using frequency/wavelength swept narrow linewidth light. Movements of the target will cause Doppler shift, and can be detected as well. As it is a heterodyne technique it is very sensitive and fast. This technique has been demonstrated as a fibre reflectometer as well.

© 1995 IEEE