Optical anisotropy of synthetic opals

Optical anisotropy of synthetic opals has been investigated by measuring the spectral dependence of polarized transmitted light at normal and oblique light incidence at various sample azimuth orientations. The optical anisotropy of thin films and bulk samples has been measured by the polarization modulation technique in the visible spectral range. The observed optical anisotropy of synthetic opals was caused by several contributions. (i) Internal strain induced during the growth process. The optical anisotropy axes along [1 1 0] and [1¯ 1 2] directions in opal lattice of fcc symmetry were indicated in the (1 1 1) plane for both thin films and bulk samples of synthetic opal. (ii) Particular features of Brillouin zone manifesting themselves as the 3rd and 6th order rotation axes in the azimuth-resolved dependence of anisotropy parameters in the (1 1 1) plane. (iii) Oblique light incidence leading to the anisotropy with respect to the incidence plane.

Research highlights▶ Optical anisotropy of synthetic opals has been investigated by measuring the spectral dependence of polarized light at normal and oblique light incidence at various sample azimuth orientations. ▶ The optical anisotropy of synthetic opals was caused by internal strain induced during the growth process. ▶ Particular features of Brillouin zone manifesting themselves as the 3rd and 6th order rotation axes in the azimuth-resolved dependence of anisotropy parameters in the (1 1 1) plane. ▶ Oblique light incidence leading to the anisotropy with respect to the incidence plane.