Birefringence in optical waveguides made by silicon nanocrystal superlattices

Abstract

The optical properties of planar waveguides were investigated with their core layers formed by a silicon nanocrystal superlattice. M-line measurements of the different waveguides were found to yield mode indices, which were then modeled by assuming anisotropic optical properties of the core layer. The refractive index values of the Si-nc-rich layer, were estimated using Bruggemann approximation method for isotropic media. The value of the form birefringence were determined using m-line measurements with the structural data obtained by transmission electron microscopy analysis. The results show a high value of 1% of the form birefringence

Structural analyses of thermal annealed SRO/SiO2 superlattices

“…In a multilayered sample, such defined birefringence is typically negative (n e < n o ), see for example Ref. [8]. For any refractive index indices, the form birefringence is found to be maximum when identical layer thickness is chosen for the two materials.…”

Optical gain in monodispersed silicon nanocrystals

“…17 The optical parameters are then extracted with a simulation software and a model of the optical anistropy for the multilayer structure. 18,19 m-line measurements allow measurement of the effective refractive index for the optical guided moded. No guided modes were observed in samples E, F, and A, while samples B, C, and D showed only one mode with the two polarizations (TE and TM).…”

“…22 A more detailed report on the birefringent properties of this kind of sample has been published else where. 18 The optical losses in the waveguide samples were measured with an experimental technique named shiftingexcitation-spot (SES). SES consists of exciting the waveguide through the surface with a small laser spot of suitable wavelength and measuring the luminescence emitted from the edge as the spot position is varied along the optical mode propagation direction, z.…”

Negative refraction and partial focusing in an anisotropic metamaterial realized by a loaded transmission line network

“…Negative refraction could be realized in such media under some different combinations of the constitutive parameters. These anomalous behaviours are different from the phenomena in other anisotropic optical structure, such as the form birefringence recently observed in nanocrystal superlattices [14,15]. The anisotropic media have been identified into four classes based on their wave propagation properties, which are called cutoff, always-cutoff, never-cutoff and anti-cutoff media [13].…”