“Dielectric-fibre surface waveguides for optical frequencies”, K.C.Kao & G.A.Hockham,
Published in the Proceedings of the IEE, Vol. 113, No.7, July 1966.

Paper 5033 E, first received 24th November 1965 and in revised form 15th February 1966.)

Link to the complete historic paper

Kindly provided by the IET. It remains Copyright of the Institution of Engineering & Technology.

This was preceded by an earlier press release from the parent company STC:

From the January 1966 Press Release

…a glass core about three or four microns in diameter, clad with a coaxial layer of another glass having a refractive index smaller than that of the core by about one per cent…

It should be noted that when these methods are perfected, it will be possible to transmit very large quantities of information (telephone, television, data, etc.) between say, the Americas and Europe, along a single undersea cable.