Characterisation of microporous sol-gel films for optical device applications

This paper describes progress towards a silica-on-silicon integrated optics technology based on sol-gel. In particular, the aim of this work is to use porous sol-gel films as a host for semiconductor microcrystallites, in order to achieve optical Kerr effect devices. Control of crystallite size is important to maximize the nonlinear effect, and also has a strong influence on band-gap, and thus the wavelength of operation. We are examining the control of pore size distribution, via sol-gel process parameters, as a means of setting crystallite size, and for this reason have developed a technique for the measurement of micropore distributions in films. Results of this technique are presented; these give the first detailed measurements of pores below 10 Å in diameter. The fabrication and measurement of initial doped films is described, giving strong evidence for quantum confinement.