core material having a greater refractive index then the surrounding material finally the waveguide 1 comprises a cladding layer 7 over the guiding layer 4 in use radiation of a desired wavelength is propagated through the cores 5 and 6 by total internal reflection arising from the interfaces between the cores 5 and 6 and the surrounding layers 3 and 7 and non densified guiding layer sol gel both the buffer and cladding layers are of a composition that does not contain functional groups which may undergo photo induced condensation reactions that would result in cross linking densification and an increase in refractive index the buffer and cladding layers are of the same material prepared as follows methyltrimethoxysilane mtmos and tetraethoxysilane teos are mixed ratio 2 1 and stirred for 1 hour dilute hcl is then added as a condensation catalyst diphenyl dimethoxysilane dpdms is added as a refractive index modifier the dpdms content can be varied resulting in a buffer cladding material of tunable refractive index the guiding layer 4 material composition is prepared as follows methacryloxymethyltriethoxysilane is hydrolysed with dilute hcl zirconium isopropoxide refractive index modifier is reacted with methacrylic acid in a separate container as with the buffer cladding layer.