MODAL BIREFRINGENCE OF THE GRADED-INDEX O PTICAL PLANAR WAVE-GUIDES OBTAINED BY COPPER-IONS-DIFFUSION IN GLASS

We present a theoretical-experimental work about modal birefringence o f the graded index optical planar waveguides obtained by copper-ions-d ifusion in glass (soda-lime). Copper has been selected as doping ion a nd substitute of the sodium in the glass network because of that they have a similar ion radius (r(Na+) = 0.95 Angstrom y r(Cu+) = 0.96 Angs trom). In principle, the basic estructure of the glass does not presen t a localizing increment of volume as a result of the ion exchange Cu --> Na+, and the refractive index is modified due to the increase of the ionic polarizability of the network. The waveguides obtained prese nt very low mechanical stress and therefore very low birefringence, th at it does them usable potentially in devices of integrated optics ind ependent to the optical polarization.