Enhancing absorption and sensitivity within structured optical fibres
J. Canning, W. Padden, D. Boskovic, M. Naqshbandi, L. Costanzo, G. Huyang, H. Bruyn, T. H. Sum, M. J. Crossley, University of Sydney (Australia)
We propose enhancing the absorption of a species inside the channels of a structured optical fibre by depositing a high index layer within the air holes. This layer draws out the optical field within the mode increasing the overlap interaction. Simulations support the general idea and an experimental demonstration is reported using a novel approach to film formation with TiO2 nanoparticles. For the sake of demonstration, we use porphyrin with carboxylic groups that attach to the TiO2. The deposition of particles well coated with porphyrin is compared to those not fully coated prior to deposition in the holes. The latter case is found to give the best results since scattering loss is reduced when the porphyrins are not initially attached to the TiO2 particle. This is expected if film formation through intermolecular forces has occurred.
