High-Reflective Templated Cholesteric Liquid Crystal Filters

Abstract

Cholesteric liquid crystals (CLCs) have been widely applied in optical filters due to Bragg reflection caused by their helical structure. However, the reflectivity of CLC filters is relatively low, commonly less than 50%, as the filters can only reflect light polarized circularly either left- or right-handedly. Therefore, a high-reflective CLC filter with a single-layer template was proposed which may reflect both right- and left-handed polarized light. The CLC filters of the red, green, blue color were fabricated by the templating technology, which show good wavelength consistency. Additionally, a multi-phase liquid crystal filter with high reflectance was demonstrated by the single-layer templating technology. The templated CLC or multi-phase liquid crystal filters show great potential applications in the optical community, reflective display, and lasing.

A hyper-reflective cholesteric liquid crystal polymer network with double layers

“…The structural colour originated from the selective Bragg reflection (l = nP; l, reflection wavelength; n, average refractive index; P, helical pitch) is generated by a periodic helical structure. During the last few decades, the polymer-stabilized CLC (PSCLC) and the CLC polymer network (CLCN) films with singlehandedness have been widely studied for their applications as polarizers, 9,10 mirrors, 11 filters, [12][13][14] and sensors [15][16][17][18] and for anticounterfeiting 19 and displays. [20][21][22] Theoretically, the reflectance of the single-handed PSCLC films is not higher than 50%.…”

Templated Twist Structure Liquid Crystals and Photonic Applications

“…Although Lin et al proposed a wide-band spatially tunable and highly reflective merged CLC template, there inevitably exist some issues such as complicated construction with the overlapping of two templates and optical loss in the interface. Hence, a highreflectivity CLC filter with a single-layer template was proposed by Gao et al, which may reflect both right-and left-handed polarized light [79]. The high-reflectivity CLC filters of red, green, and blue color were fabricated by the templating technique, which showed good wavelength consistency.…”

Photonic band edge and defect modes in 1D cholesteric liquid crystals

“…This selective reflection creates a photonic band gap between λ 1 = n o p and λ 2 = n e p, where n o and n e are the ordinary and the extraordinary refractive index, respectively, and p is the cholesteric pitch, the distance at which the molecular orientation twists by full angle 2π. [2][3][4][5][6] In the field of photonics, CLCs have been used for reflective displays, diffractive optical elements, 7,8 and tunable filters, [9][10][11] allowing for precise manipulation of transmitted light by adjusting external parameters such as temperature, electric fields, or mechanical stress. Additionally, CLCs can be utilized as optical micro-resonators and even micro-lasers if doped with appropriate dye.…”