{\rtf1\ansi\ansicpg1252\deff0{\fonttbl{\f0\fswiss\fprq2\fcharset0 Arial;}} {\*\generator Msftedit 5.41.15.1503;}\viewkind4\uc1\pard\lang1033\f0\fs24 The Sol-Gel Process\par \par [0044] The all-optical switches of the present invention can also be fabricated by incorporating SWNT into a silica by the sol-gel process. A "sol" or hydrosol is a colloidal dispersion in a liquid. A "gel" is a colloidal suspension of a liquid in a solid, forming a jelly-like material in a more solid form than a sol. The term "sol-gel" refers to a process of making glass in which the glass is formed at low temperatures from suitable compounds by chemical polymerization in a liquid phase. A gel is formed from which glass is derived by the successive elimination of interstitial liquid and the collapse of the resulting solid residue by sintering. \par \par [0045] There are two main techniques used to synthesize gels at room temperature. The first technique consists of a common reaction, which occurs in nature, where silica chemical species diluted in aqueous solutions condense to lead to the formation of silica network. Such a condensation may occur in various aqueous solutions depending on pH and salt concentration. Different morphologies may be obtained. For silica, the most known is the precious "opal." \par \par [0046] The second technique to produce silica from solution corresponds to a chemical reaction involving metal alkoxides and water in an alcoholic solvent. The first reaction is an hydrolysis which induces the substitution of OR groups linked to silicon by silanol Si--OH groups. These chemical species may react together to form Si--O--Si (siloxane) bonds which lead to the silica network formation. This phase establishes a 3D network which invades the whole volume of the container. Of course, for these two syntheses, the liquid used as solvent to perform the different chemical reactions remains within the pores of the solid network. A gel is thus obtained. This two-phased material consists of shaped solid exhibiting specific properties. \par \par [0047] The sol-gel process can be applied to incorporate SWNT into a silica. The SWNT-silica composite then can be directly put into an optical fiber for switch applications. Furthermore, by applying the lithography and lift-up techniques, one can pattern the SWNT-silica material into an integrated optical system for future communication and computing applications. \par \par }