Development of Semiconductor Laser for Optical Communication

The performance, functionality and productivity of the semiconductor laser have been dramatically improved since its invention in 1962. Today it came to be indispensable for our life as optical components connecting home and the Internet as well as long-distance large-capacity trunk networks. It may be said that the information revolution pulled by the explosive spread of the Internet is originated from three innovations from 1969 to 1970, the room temperature continuous wave operation of the semiconductor laser, the invention of the low loss optical fiber and the beginning of ARPAnet (Advanced Research Projects Agency Network) experiment. In those days, we already started research and development of optical fiber and compound semiconductor materials such as GaAs which was widely used as a substrate material of compound semiconductor devices. We started the research and development of compound semiconductor devices for optical communication from the middle of the 1980’s in order to establish optical communication business vertically integrating technology from materials, devices to systems. This paper describes the development of the semiconductor laser for optical communication focusing mainly on Sumitomo Electric’s R&D activities with the progress of transmission technology. By the beginning of 1990’s 1.3 μm Fabry-Perot (FP) lasers were developed for the application to metro-access networks. In the 1990’s practical use of wavelength division multiplexing (WDM) started and pumping lasers for fiber amplifiers and distributed feedback (DFB) lasers were developed for WDM application. In the 2000’s with the recovery from the IT bubble burst, further improvements of modulation speed, power consumption and functionality were progressed by the development of new material, vertical cavity surface emitting laser (VCSEL) and photonic integration. 2. Development of high performance FP laser