Semiconductor laser light sources seem to have arrived at a stage of frequency control through several development stages including transverse-mode and longitudinal-mode control. A strong desire to apply semiconductor lasers to coherent optical fiber transmission systems or measurement systems has made possible narrow spectral linewidth tunable semiconductor lasers. Frequency or wavelength tunability will also be important in wavelength division multiplexing (WDM) or frequency division multiplexing (FDM) transmission systems. Especially, frequency tunability will be inevitable in future coherent FDM systems with many closely located channels.
© 1987 Optical Society of AmericaPDF Article