ABSTRACT
The era of optical ber communications began with the paper by Kao and Hockham then at Standard Telecommunications Laboratories (STL) in 1966 [1]. The paper discussed the theory and potential for optical ber communications, predicting loss below 20 dB/km if metal impurities were removed. Work at Corning in the early 1970s pioneered silica-based optical bers, made using vapor deposition techniques [2]. Subsequent efforts during the 1970s quickly led to a Rayleigh-scattering limited loss of ∼0.2 dB/km at ∼1550 nm by signicantly minimizing transition metal and hydroxyl impurities in silica glass.
