Ultra-low refractive index mesoporous substrates for waveguide structures

• Published in: Physica status solidi. A, Applications and materials science Vol. 204; no. 11; pp. 3676 - 3688
• Main Authors: Konjhodzic, D., Schröter, S., Marlow, F.
• Format: Journal Article
• Language: English
• Published: Berlin WILEY-VCH Verlag 01.11.2007; WILEY‐VCH Verlag
• Subjects: 42.79.Gn; 68.37.−d; 68.55.−a; 78.20.Ci; 81.20.Fw
• ISSN: 1862-6300; 1862-6319
• DOI: 10.1002/pssa.200776405

Mesoporous silica films were synthesized by dip‐coating. In this process, evaporation induced self‐assembly leads to the formation of an ordered pore structure. Two types of films with different optical properties have been found in dependence on the humidity during the synthesis. The synthesis field has been explored in order to locate optically perfect films. Both film types, denoted as A and B, have been characterized by small angle X‐ray scattering (SAXS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). From these results, the different structures for the two film types have been determined. A‐type films have a stable worm‐like structure, whereas for B‐type films a sustained lamellar structure has been found. A very low refractive index has been measured for A‐type films and its stability has been examined. These films have been used as low‐n supports to realize waveguide structures based on polymers, Ta2O5, and the ferroelectric material PZT. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)