Anisotropic effective permittivity of an ultrathin gold coating on optical fiber in air, water and saline solutions
Public Deposited- Resource Type
- Creator
- Abstract
The optical properties of an ultrathin discontinuous gold film in different dielectric surroundings are investigated experimentally by measuring the polarization-dependent wavelength shifts and amplitudes of the cladding mode resonances of a tilted fiber Bragg grating. The gold film was prepared by electron-beam evaporation and had an average thickness of 5.5 nm ( ± 1 nm). Scanning electron imaging was used to determine that the film is actually formed of individual particles with average lateral dimensions of 28 nm ( ± 8 nm). The complex refractive indices of the equivalent uniform film in air at a wavelength of 1570 nm were calculated from the measurements to be 4.84−i0.74 and 3.97−i0.85 for TM and TE polarizations respectively (compared to the value for bulk gold: 0.54-i10.9). Additionally, changes in the birefringence and dichroism of the films were measured as a function of the surrounding medium, in air, water and a saturated NaCl (salt) solution. These results show that the film has stronger dielectric behavior for TM light than for TE, a trend that increases with increasing surrounding index. Finally, the experimental results are compared to predictions from two widely used effective medium approximations, the generalized Maxwell-Garnett and Bruggeman theories for gold particles in a surrounding matrix. It is found that both of these methods fail to predict the observed behavior for the film considered.
- Language
- Identifier
- Citation
- Zhou, W., Mandia, D. J., Barry, S. T., & Albert, J. (2014). Anisotropic effective permittivity of an ultrathin gold coating on optical fiber in air, water and saline solutions. Optics Express, 22(26), 31665. https://doi.org/10.1364/oe.22.031665
- Date Created
- 2015-05-21
Relations
- In Collection:
Items
Thumbnail | Title | Date Uploaded | Visibility | Actions |
---|---|---|---|---|
mandiazhou1-article.pdf | 2023-05-09 | Public | Download |