No abstract

We track the non-uniformity of a wide area liquid crystal device using multiple cross-polarized intensity measurements. They give us not only accurate estimates of the core physical liquid crystal parameters, such as elastic constants, but also spatial maps of the device properties, including the liquid crystal thickness and pretilt angle. A bootstrapping statistical analysis, coupled with the multiple measurements, gives us reliable error bars on all the measured parameters.

Enhanced, photoactive response can be realised by integrating liquid crystals with photoalignment or photoconductive alignment layers. Such cells, asymmetric by design, need to be monitored for the stability and uniformity, especially in the regions exposed to light. In this work, we report on an integrated, versatile model and technique to characterise their core parameters as well as more subtle effects, such as the strength of anchoring energy. The snapshot method also provides twodimensional maps of the cells' thickness, pretilt angle and uniformity.

Babinet complementary patterns of a spectrally tunable metamaterial incorporating a nematic liquid crystal are normally assumed to exhibit the same tuning range. Here we show that for a hybrid, terahertz liquid crystal-metamaterial, the sensitivity of its resonances to the variations of the refractive index differs substantially for the two complementary patterns. This is due to a mismatch between the alignment of the liquid crystal and the direction of the local electric field induced in the patterns. Furthermore, and more intriguingly, our experimental data indicate that it is possible to shift the resonance of the positive metamaterial pattern beyond the limit imposed by the alignment mismatch. Our analysis suggests that the observed anomalous frequency shift result from the orientational optical nonlinearity of a nematic liquid crystal.