Question : basic physics - optical fibres

Hi

Why do optical fibres have a cladding layer? Most things says they have this layer to keep the light in by total internal reflection, but you would get TIR between the core and air anyway wouldn't you if the core has RI of 1.5 (typically) and air has RI of 1 (near enough). ?

thanks

Answer : basic physics - optical fibres

Yes, Air is sufficient and works. Earlier OFCs used that... But then they found the advantage of having a dedicated cladding material.
Read this history: http://en.wikipedia.org/wiki/Optical_fiber#History
Quote: previous optical fibers had relied on air or impractical oils and waxes  as the low-index cladding material.