  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.
