Symmetric Continuously Tunable Photonic Band Gaps in Blue-Phase Liquid Crystals Switched by an Alternating Current Field

Abstract

Symmetric continuously tunable three-dimensional (3D) liquid photonic crystals have been investigated using self-organized blue-phase liquid crystal films. The photonic band gap in the overall visible spectrum can be tuned continuously, reversibly, and rapidly as the applied electric field changes. After driven by the applied field, four-time enhancement of the reflectivity results in more vivid reflection colors. A lasing emission of tuning working wavelength has been demonstrated by using the dye-doped blue-phase liquid crystal film. With the advantages of fast response speed, no alignment layer, large-scale electrically shift of the photonic band gap, and macro optical isotropy, this self-assembled soft material has many potential applications in high-performance reflective full-color display, 3D tunable lasers, and nonlinear optics.

Diffusionless transformation of soft cubic superstructure from amorphous to simple cubic and body-centered cubic phases

“…BPI and BPII as soft artificial three-dimensional photonic crystals 26 , 41 – 43 , show promise for optical applications owing to their photonic band structures 54 , 55 . To further understand the optical properties of the DLPT process of BPLCs, ARM was used to characterize the two-dimensional transmittance/reflectance spectra (see Supplementary Figs.…”

“…Blue-phase liquid crystals (BPLCs) are typical soft cubic phases 8 , 14 – 19 that combine the order of solid molecular crystals and the fluidity of the liquids. BPLCs have attracted intense scientific and engineering interest in recent decades because they exhibit narrow photonic bandgaps and submillisecond response times, do not require alignment layers, and have potential applications in adjustable lasers 20 – 26 , displays 27 – 29 , and nonlinear optical devices 30 , 31 . BPLCs are analogous to atomic crystals 14 , 17 , 32 , 33 based on their highly ordered structures at both the molecular (orientational molecular order) and mesoscopic scales (chiral arrays of double-twisted cylinders (DTCs), which are induced by the self-assembly of the molecules).…”

3D Chiral Photonic Nanostructures Based on Blue‐Phase Liquid Crystals

“…Monodomain BP textures can be induced by rotating the BP lattices under an electric field. [ 137–142 ] Chen and Wu prepared monodomain BPLCs by applying an alternating current electric field, as shown in Figure a. [ 137 ] POM analysis revealed multidomain platelet textures, indicating the random alignment of BP lattices before the application of an electric field.…”

“…Du et al prepared electric field‐induced monodomain BP nanostructures with a high reflectivity (Figure 6b). [ 141 ] The BP lattices, which were randomly oriented before the electric field was applied, oriented uniformly after the application of an electric field. The self‐organized monodomain BP films have potential application in 3D tunable lasers, nonlinear optics, and high‐performance full‐color reflective displays.…”

Blue Phase Liquid Crystals with Tailored Crystal Orientation for Photonic Applications

“…where n is the average refractive index of BPs, a is the lattice constant of BPs, (hkl) is the Miller indices representing the crystal orientation, and θ is the propagation angle of light in BPs with respect to the normal direction of a Miller plane. Because of the external stimuli-responsivity of BPs, they can be easily switched and tuned by controlling temperature [6,7], by applying an electric field [7][8][9][10][11], and by illuminating light [12,13], making them applicable to various photonic applications such as displays [14], photonic crystal lasers [6,[15][16][17][18], biosensors [19,20], optical filters [21], polarization converters [22], and diffractive optics with the capability of nonmechanical beam steering [23,24]. Despite the technological potential of BPs, several issues have been raised to achieve tailored light-matter interaction for practical applications.…”