| Your best bet is to goggle "Fiber Optics" or search Webopaedia"
Given the speed of light through a strand roughly the size of a human hair, the low cost of spinning glass fiber, the light weight of a cable, the cost compared to copper. Fiber optics are the current trend.
Originally (at least as far as I know) Fiber optics started out at a optics company in Pelham Manor, just north of the NY city. It was originally developed for dentists and doctors until the world fell caught up with the possibilities.
The only reason I know that much is because my wife worked for the Sales Manager, while the product was still in the development stages. After it took off, the SM left and started his own company.
Still if you want detailed technical info., I suggest Googling it | 
Linear Mode
