Development of Semiconductor Laser for Optical Communication

Abstract

The performance, functionality and productivity of the semiconductor laser have been dramatically improved since its invention in 1962. Today it came to be indispen sable 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 tempera ture 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 semi conductor devices. We started the research and develop ment of compound semiconductor devices for optical communication from the middle of the 1980’s in order to establish optical communication business vertically in tegrating technology from materials, devices to systems. This paper describes the development of the semi conductor 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 dis tributed 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 2-1 Materials and crystal growth techniques Wavelengths used for optical communication are mainly 1.55 µm for long-distance transmission and 1.3 µm for short- and mid distance transmission due to the min imum loss and minimum dispersion in optical fiber, re