Tuning selective reflection of light by surface anchoring in cholesteric cells with oblique helicoidal structures

TL;DR

This paper demonstrates that the selective reflection wavelength of oblique helicoidal cholesteric liquid crystals can be precisely tuned by surface alignment, enabling potential sensing applications through controlled spectral shifts.

Contribution

It shows how surface alignment influences the reflection wavelength in cholesteric cells with oblique helicoidal structures, providing a new method for tuning optical properties.

Findings

Surface alignment controls the reflection wavelength shift.

Perpendicular alignment causes a blue shift.

Planar alignment causes a red shift.

Abstract

Selective reflection of light by oblique helicoidal cholesteric (ChOH) can be tuned in a very broad spectral range by an applied electric field. In this work, we demonstrate that the peak wavelength of the selective reflection can be controlled by surface alignment of the director in sandwich cells. The peak wavelength is blue-shifted when the surface alignment is perpendicular to the bounding plates and red-shifted when it is planar. The effect is explained by the electric field redistribution within the cell caused by spatially varying heliconical ChOH structure. The observed phenomenon can be used in sensing applications.