While engineers at Standard Telecommunications Laboratories, an ITT subsidiary, Charles Kao and George Hockham achieved the first conceptual breakthrough in the development of fiber optic transmission systems (FOTS). In 1966, Kao and Hockham determined that optical fibers of fused silica could satisfy signal attenuation requirements by overcoming issues of absorption, diffusion, and bending loss. At the time, attenuation of 20 dB per kilometer was considered satisfactory for a commercially viable system. Contemporary FOTS are designed around attenuation levels in the range of 1.5