A model for the refractive index of amorphous silicon for FDTD simulation of photonics waveguides

This paper presents an analysis of the material quality influence for amorphous silicon waveguides for microphotonic applications. Material quality is taken into account by a model based on the absorption coefficient data obtained by Constant Photocurrent Measurement (CPM) in the near infrared region. The GUTL (Gauss-Urbach-Tauc-Lorentz) model has been presented as an extension of the standard Urbach-Tauc-Lorentz model and proposed as a predictor for the wavelength dependent optical constants of amorphous silicon in the near infrared spectra. Values produced for the GUTL model have been used as input for a set of FDTD simulations, taking in consideration different material qualities and waveguide dimensions directed to study the characteristics of amorphous silicon waveguides embedded in a SiO
₂
cladding.