The synthesis and application of novel benzodithiophene based reactive mesogens with negative wavelength dispersion birefringence

Abstract

The factors influencing negative wavelength dispersion are investigated for a series of benzodithiophene based photopolymerisable liquid crystals.

Engineering the chemical structure of H-shaped reactive molecules for negative dispersion of retardation

“…On the other hand, a negative dispersion (ND) retarder whose Δn increases with longer λ may enable an achromatic response with constant Γ. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] Several kinds of approaches have been suggested for the fabrication of ND retarders. The traditional method to make an achromatic retarder is stacking two or more PD retarders.…”

“…9,10 More recently, novel retarder materials have been reported where ND of Δn is achieved using a single layer. [11][12][13][14][15][16][17][18][19][20] The dispersion of refractive index becomes weak as the wavelength of light is farther away from the absorption resonance wavelength. [11][12][13][14][15][16][17][18][19][20] If the material absorbs longer and shorter wavelengths of light along the n e and n o directions, respectively, then n e decreases more than n o with longer λ, resulting in ND of Δn.…”

“…[11][12][13][14][15][16][17][18][19][20] The dispersion of refractive index becomes weak as the wavelength of light is farther away from the absorption resonance wavelength. [11][12][13][14][15][16][17][18][19][20] If the material absorbs longer and shorter wavelengths of light along the n e and n o directions, respectively, then n e decreases more than n o with longer λ, resulting in ND of Δn. This idea was experimentally proved by limited groups using copolymers [11][12][13][14] and RMs.…”

“…This idea was experimentally proved by limited groups using copolymers [11][12][13][14] and RMs. [15][16][17][18][19][20] In these days, the single layer approach using RM materials is regarded as a promising solution for future optical components due to their small thickness and simple fabrication process. [15][16][17][18][19][20] Nevertheless, very limited numbers of ND RM materials have been reported.…”

“…[15][16][17][18][19][20] In these days, the single layer approach using RM materials is regarded as a promising solution for future optical components due to their small thickness and simple fabrication process. [15][16][17][18][19][20] Nevertheless, very limited numbers of ND RM materials have been reported. [15][16][17][18][19][20] In addition, most of the ND materials were developed in industry and academic studies on the effect of the chemical structure and the molecular orientation on the optical properties have been rarely reported.…”