The problem at the time was that the best optical glasses made using conventional methods could only carry light for about 10 metres, so Kao went in search of an even clearer glass. He found it in the form of that ultra-pure fused glass first developed by James Franklin Hyde at Corning back in the 1930s. Kao calculated that light could travel for kilometres down such a glass with barely any data loss. And since the bandwidth of tiny fibres was so much greater than far thicker copper ones, even an incredibly thin strand could carry multiples more information.
