Study of thermally induced optical bistability in a twisted nematic liquid crystal

Plasmonic all-optical bistable device based on nematic liquid crystal

“…Values of the width of bistability W, defined as W = (I 1 − I 2 )/I 1 [13], are shown in Table 1. Sample B is much wider than sample A.…”

“…Some papers have appeared on the optical bistability in nematic or cholesteric LCs, operating at low illumination. These studies used a Fabri-Perot cavity [11], the selective reflection in chiral LCs [12], a crossed polarizer configuration [13], or surface plasmons (SPs) in the attenuated total reflection (ATR) configuration [14,15]. The phase transition from the LC phase to the isotropic phase or changes in the helical pitch of chiral nematic LCs, due to irradiation, gives rise to a large change in the local refractive index.…”

Electro-optic control of non-linear optical effects in twisted nematic liquid crystal cells

“…Taking into account the previous equations, the condition P a = P d gives (12) We have bistability when a n/2 twisted nematic liquid crystal cell is bounded by two crossed polarizers. The optical system is transparent.…”

“…We have shown how these parameters can be computed for the case of self-transparency (eqs. (10), (12)) and for the case of bistability (eqs. (17), (15)).…”

“…While light absorption in the front polarizer depends on the polarization state of the impinging light, and therefore has a linear behavior, the light absorbed by the rear polarizer, since light polarization is rotated by the cell in the nematic area while it is unaffected by the isotropic hole, depends on the hole diameter which, in turn, is determined by light absorption itself. A new family of non-linear optical devices based on this effect has recently been proposed [11][12][13][14]. Even in the presence of a central isotropic hole light, absorption in the nematic area can be controlled by the application of an electric field in the direction orthogonal to the cell so that the non-linear optical behavior can be electrically controlled.…”