Asymmetrical polarization-dependent scattering and reflection in a sole cell of polymer network-90° twisted nematic liquid crystals

Abstract

The anisotropically intrinsic scattering and reflection of a sole cell of polymer network-90° twisted nematic liquid crystals (PN-90° TNLCs) without any polarizer are proposed. Light with specifically linear polarizations, incident from one direction, can penetrate the PN-90° TNLCs with applied voltage. The polarization direction of the output beam will be rotated 90°. The same linearly polarized light, incident from the other direction, will be scattered because it encounters the refractive indices mismatch of various LC domains. The reflection, resulting from the boundaries of LCs and polymers, also shows optical anisotropy. Such LC devices can be applied as scattering-type linear polarizers.

High-Contrast and Scattering-Type Transflective Liquid Crystal Displays Based on Polymer-Network Liquid Crystals

“…Afterward, the prepared LC cells were illuminated with UV light with an intensity of approximately 10 mW/cm 2 for~120 min to form the smooth PN gradually. Photo-initiator was not used herein to ensure the PN could be formed smoothly along the orientation of local LCs [16,27]. The cell treated with orthogonal (parallel) mechanical rubbing was named as the PN-90 • TNLC (H-PNLC) cell.…”

“…Based on Figure 6, scattering performance (SP) of H-PNLCs applied with 18.5 Vrms, namely SPH-PNLCs, can be described by the following equation, in which the reflection caused by air-glass boundaries is ignored, when the incident light is unpolarized [16,32,33,34]:…”

“…Based on Figure 6, scattering performance (SP) of H-PNLCs applied with 18.5 V rms , namely SP H-PNLCs , can be described by the following equation, in which the reflection caused by air-glass boundaries is ignored, when the incident light is unpolarized [16,[32][33][34]: Overall, based on Figure 6, the value of SP H-PNLCs of incident x-LPL (y-LPL) should be higher (lower) than that of SP of PN-90 • TNLC cell of incident y-LPL (x-LPL). Overall, the scattering performance of the H-PNLC cell is better than that of the PN-90 • TNLC cell, so ST-TRLCD#2 using an H-PNLC cell (Figure 4) can achieve better CR than ST-TRLCD#2 using a PN-90 • TNLC cell ( Figure 5).…”

“…[1][2][3][4][5][6][7][8][9][10][11]. PN-90 • twisted nematic LC (PN-90 • TNLC) cells have also extensively been studied [12][13][14][15][16][17]. One of the most interesting properties of a PN-90 • TNLC cell is its asymmetrical transmission of linearly polarized light (LPL).…”

“…Theoretically, if all LCs are rotated on the xz-plane by the applied voltage of 18.5 V rms , the integral of d comes close to 0, because y-LPL incident light always encounters n o of LCs in all mLCds, and ∆n effy is close to 0. The minimum transmittance plotted as the blue curve ofFigure 6is not equal to 0, because the polymer fibrils do not actually grow perfectly along the local LCs, indicating that the LCs are not completely rotated on the xz-plane by the applied electric fields.The polarization states of the x-LPL and y-LPL change to various elliptically polarized lights (EPLs) with different major and minor axes at different positions while traveling in the PN-90 • TNLC cell applied with a voltage of 18.5 V rms[16,17,35]. The components of EPLs with polarization that are parallel to the local LCs are scattered, whereas the components of EPLs with polarization that are perpendicular to the local LCs are not scattered because it encounters the n o of LCs in all mLCds.…”