Integrated optical devices achieved by sol-gel process

Recently, the sol-gel process, already used in optical science as protective coating and anti-reflection layer, appears to be a low cost alternative to the conventional technologies such as LiNbO3, ion exchange in glass or plasma deposition of dielectric on silicon. Moreover, this is a low temperature process: which enables the realization of hybrid opto-electronic compounds. A buffer layer, also made by sol-gel process, isolates the guide from the silicon substrate and confines the guided modes into the center of the guide. This yields very low insertion losses. Moreover, the use of a hybrid organo-mineral sol-gel enables to obtain thick layers that reduce the coupling losses between guides and single mode optical fibers. At last, these devices an encapsulated with an anti-scratch protective coating which reduce the risk of damage during handling. It is possible nom to produce high performance channel waveguides (propagation losses less than 0.1 dB/cm) by simple UV-imprinting in a photocurable sol-gel layer. The control of the process parameters opens the route to the fabrication of a number of passive optical devices, such as 1x8 beam splitter with only 7dB of total losses at 1.3 mu m wavelength, and directional coupler which are working as router and/or splitter. The fabrication and characterization of such devices are presented in this paper.