Electric field-controlled transformation of the eigenmodes in a twisted-nematic Fabry–Pérot cavity

Abstract

The polarized optical states in the transmission spectrum of a twisted-nematic Fabry–Pérot cavity with the distinctly broken Mauguin’s waveguide regime have been theoretically and experimentally investigated. Specific features of the electric field-induced transformation of the polarization and spectral characteristics of eigenmodes of the neighboring series at the overlap resonant frequencies have been examined. It is demonstrated that the linear polarizations of eigenmodes at the cavity boundaries remain nearly orthogonal and their frequency trajectories reproduce the avoided crossing phenomenon. The experimental data are confirmed analytically and by the numerical simulation of light transmission through the investigated anisotropic multilayer with the use of a Berreman matrix method. The results obtained can be generalized to any materials with the helix response.

Anomalous Spectral Shift of o-Modes in Multilayer Photonic Structure Induced by Homeotropic–Homeoplanar Transition in Chiral–Nematic Defect Layer

“…The modes corresponding to them repel each other apart relative to the avoided crossing point while exchanging the polarization state re ↔ ro. In particular, the role of the avoided crossing point is played by the wavelength λ c , at which the partial cavity modes would intersect in the absence of coupling on the mirrors [36]. The investigated PS/CN structure is not an exception in a series of chiral photonic crystals.…”

“…Despite the variable ellipticity of the cavity modes in a chiral medium, their polarization on the mirrors is linear. If the re and ro cavity modes tend to cross in the vicinity of the point corresponding to the maximum possible coupling of the partial te and to waves, then the avoided crossing phenomenon should be expected [36]. The essence of this phenomenon is that the linear polarization of the approaching re and ro modes does not coincide with the direction parallel (re) or orthogonal (ro) to the local director of the layer adjacent to the mirror.…”

Optical modes of multilayered photonic structure containing nematic layer with abnormal electroconvective rolls

“…With increasing voltage, one can observe series of avoided crossings of the transmission peaks in the spectrum, which cause a bisector (at angles of ±45 • to the nematic director) polarization of both cavity modes. The enhancement of the mode coupling leads to the short-wave shift of the ro-modes [13]. Vice versa, in the vicinity of the spectral points corresponding to the Gooch-Tarry minima, the weak mode coupling does not affect the spectral position of the ro-modes.…”