Fiber Optics in Brazil

Abstract

With the invention of the Laser in 1960, communications engineers became excited at the possibility of using it as a source of carrier waves with the prospect of enormously large bandwidths. Unfortunately, no suitable transmission path was available until a detailed study by Kao & Hockham in 1966 suggested that cladded glass fibers might be used to guide laser light for telecommunications purposes. Commercially available fibers had losses of the order of 1000 dB/km and an improvement of two orders of magnitude was called for to make an economically viable system. A considerable breakthrough occured in 1970 when Corning Glass Works reported fiber losses of 20 dB/km. This result produced a very strong impetus to the field and soon fiber optics became a booming field with research and development activities being started around the globe. Thus although in 1970, the potentialities of optical fiber were seen to be very attractive, no suitable sources were available. The semiconductor laser with its very small size, high efficiency, and capable of being directly modulated at high speed was the obvious choice, but no laboratory as yet had produced a suitable laser for use in optical communications.