Abstract

The unique intrinsic optical properties of new alkoxide solgels derived (type V and VI) gel silica optics are compared with types I and II fused quartz optics and types III and IV synthetic fused silica optics. Type V gel silica has excellent transmission in the vacuum ultraviolet with the cutoff near theoretical, based on quantum mechanical calculations, at 159 nm. The high optical transmission extends up to 4200 nm with no OH absorption peaks in the near infrared. Other physical properties and structural characteristics of type V gel silica are similar to the highest grade fused silica but offer the important advantages of netshape casting with high accuracy. This eliminates the labor intensive grinding and polishing of many precision optical components. In addition, optical elements such as Fresnel lenses or elements with internal cavities can be made with the solgel type V silica process. Type V gel silica also has a lower coefficient of thermal expansion than traditional commercial vitreous silica optics and the lower expansion extends over a broader temperature range. It is also possible to make optically transparent gel silica with a controlled volume fraction inside of pores. This new material for optical use is called type VI gel silica. The ultraporous type VI gel silica optics can be impregnated with up to 30-40% by volume from a second phase that can be optically active organic or inorganic compounds. The type VI porous gel silica can also be used as a substrate for laser densification of waveguides.

© 1989 Optical Society of America