*4.3.1 Guest-host display*

These types of display systems were first introduced by Heilmeier and Zanoni [66]. As the name suggests, in these systems light is absorbed by the guest material, which are generally dichroic dye molecules, dissolved in a host LC material. Dichroic dye molecules are rod-shaped molecules, which absorb light of certain wavelength more along one axis than the other. Dye molecules get dissolved in LC and orient along with LC molecule. Upon application of external field, the rotation of absorption axis of dye molecule along with LC molecule modulates light transmission. Mainly, there can be three types of GH displays exist: the Heimeier type, the double-layer type and the PDLC type, which uses 1, 2 and zero polarizers, respectively [15, 67].
