Optimization of optical properties of high chiral planar waveguides obtained by sol-gel method

High optical quality chirowaveguides have been successfully prepared using a synthesized chiral organo-modified silane (ORMOSIL) precursor chemically transformed to a pre-condensed active material prior to dip coating. The chemical and physical parameters are optimized to elaborate in a single step dip coating 4.5 μm thick planar chirowaveguides presenting low loss (<1 dB/cm). The refractive index can be adjusted from 1.630 to 1.655 at 543.5 nm by adding tetraethoxysilane (TEOS) in the solution and by increasing the annealing temperature and time. It is shown that only 10% racemization occurs when annealing is conducted under vacuum at temperature lower than 120 °C during less than 10 h. Finally, the highest specific optical rotation (OR) obtained is 7°/mm.