Preparation of homogeneous microspheres for optical cavity

Using phenyltriethoxysilane (PTES) as a starting material, preparation of pore-free organic-inorganic hybrid spheres of micrometer sizes have been investigated for their application to optical cavities. Undesirable imperfections such as inside pores which scatter light decrease the quality factor (Q value) of a sphere. Centrifugation technique using potassium tartrate aqueous solution as a density-changing solvent from 1.0 to 1.4 was developed to separate pore-free particles from as-prepared particles. The percentage of pore-free particles was estimated about 5% of the weight of as-prepared samples. The size distribution of precipitated particles in various density solvents was estimated by scanning electron micrograph. Larger density, pore-free particles had a smaller size compared with those of low density, pore-containing spheres. (C) 1999 Elsevier Science B.V. All rights reserved.