Application of the Sol-Gel Method at the Fabrication of Microstructure Fibers

This paper presents results on using the sol-gel process for the preparation of microstructure fibers (MSFs). In this preparation the sol-gel method is used for the formation of bonds between silica tubes and silica rods in the input stacks for MSF drawing and for filling-in the interstices between these parts. Gels applied on the stacks were prepared from sols composed of tetraethoxysilane, phosphorous oxychloride, boron tribromide, ethanol, HCl and water. Pastes prepared from the sols and solid fabricated through heat treatment of the sols at 1000°C were also used. The sols were applied on the stacks by the dip-coating method and the pastes were applied manually. The formed xerogels were heat-treated at temperatures of up to 1000°C. The MSFs of the grapefruit type were drawn from the stacks at a temperature of about 1900°C. Waveguiding properties of the fibers were examined under their excitation by an inclined collimated beam. It has been found that the sol-gel method is suitable particularly for filling-in the interstices at the end of the stack, which enables pressure control inside holes of the stack during MSF drawing.