We have recently reported a novel approach to producing voltage programmable optical devices in which static wrinkles
are created at the surface of a thin film of oil [Nature Photonics 3(7), 403 (2009)]. The oil coats a 2d electrode pattern
and dielectrophoretic forces created from the non-uniform fringing electric field profiles near to the electrodes determine
how this pattern is "imprinted" at the remote oil/air interface. Sinusoidal wrinkles have been created on the surface of
decanol oil with pitch lengths of between 20 and 240 micrometers and have been rapidly switched on in less than 40
microseconds. Non-sinusoidal surface wrinkles with higher harmonics appear when electrodes with the larger pitches are
used in conjunction with an oil that has a lower dielectric constant, for example hexadecane. It is found that the higher
Fourier components of the shape of the periodic wrinkle decay faster than the fundamental component as the thickness of
the oil film is increased.
Nematic phase gratings have been studied in which a planar nematic layer of thickness 17.2 μm is sandwiched between
two glass substrates coated with an alignment polymer. The upper substrate is a continuous earth plane and the lower
substrate has a patterned electrode of interdigitated stripes (electrodes and gaps are both 40 μm wide). Reorientation of
the nematic liquid crystal occurs in response to d.c. electric fields applied between the interdigitated electrodes. These
nematic reorientation regions have been used to investigate the influence of the flexoelectric polarisation in the nematic
liquid crystal by observing the resultant (i) movement of tilt fringes in a Mach-Zehnder interferometer, and (ii) optical
diffraction patterns. In the Mach-Zehnder interferometer the periodic variation of the refractive index resulting from the
periodic distortion profile is measured directly from the displacement of the tilt fringes. The asymmetry in the response
to positive and negative polarities of the d.c. voltage for both measurement techniques is directly related to the sum of
the flexoelectric coefficients, e1 + e3.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.