Eigenmodes in a photonic structure with a torsion-deformed nematic liquid crystal exposed to a magnetic field

Gunyakov, Vladimir A.; Parshin, Alexander M.; Timofeev, Ivan V.; Zyryanov, Victor Ya. Physical Review E. DOI:https://doi.org/10.1103/PhysRevE.102.042701

The polarized components of transmission spectrum of a multilayered photonic structure containing a nematic liquid crystal under the magnetic-field-induced torsion deformation have been investigated. Since the planarly twisted director structure of the nematic is unrelated to a decrease in its optical anisotropy, the control of the polarization and spectral characteristics of the eigenmodes is based on the occurrence of a geometric phase, whose contribution gradually increases upon nematic deformation. Along with the previously observed blue shift of the cavity o modes, the anomalous shift of the cavity e modes to the long-wavelength region (red shift) of the transmission spectrum has been detected. It has been shown that the countershift of the modes narrows the intermode interval. Remarkably, the extremal approaching of e and o modes in magnetic field Hex occurs below the avoided crossing phenomenon observed in the stronger equalization field Heq (Hex<Heq). The experimental results have been interpreted by the numerical simulation of the transmission spectra of the chiral photonic structure using the transfer matrix method.