Heliconical Cholesterics Endows Spatial Phase Modulator with an Electrically Customizable Working Band

Abstract

Multidimensional and large‐scale parallel manipulation of light, especially on‐demand tailoring of the working frequency and spatial phase front, is highly pursued in modern optics. Here, broadband tunable planar optics is demonstrated by electrically driving the nanohelix of photopatterned heliconical cholesterics. By preprogramming the initial orientation of the helixes using a dynamic‐mask photoalignment technique, spatial geometric phases can be arbitrarily encoded to the reflected light in a reconfigurable way. Due to the reversible electrically variant pitch of the heliconical superstructures, the reflective Bragg band can be precisely selected in the range from 380 to 1550 nm. In addition to wavelength selection and geometric phase modulation, spatial amplitude modulation and spin reversion can be further expected. This may offer a platform for full‐dimensional manipulation of light, including wavelength/frequency, phase, amplitude, time, and spin, thus upgrading optical information processing techniques.

Immersion‐Triggered Active Switch for Spin‐Decoupled Meta‐Optics Multi‐Display

“…Note that in our design, because the chosen unit cell is achiral, the geometric phases (ϕ PB = 2θ) should exhibit the same absolute values but with opposite signs (ϕ PB or -ϕ PB ), depending on the spin of incident polarizations (LCP or RCP, respectively). [49,50] In order to decouple the phase maps, we utilize the spin-independent propagation phases of the nanopillars (ϕ air and ϕ liq ), which relate to the nanopillar dimensions and surrounding states, as shown in Figure 2b. For The phase differences are designed to vary linearly from −3π/2 to 3π/2 with an interval of π/2 for the seven structures.…”

Reflective optical vortex generators with ultrabroadband self-phase compensation

“…Heliconical cholesteric is introduced for ultrabroadband tunable narrow bandgap planar optics. The OV generator, beam deflector, and off-axis lens with a customizable working band in the shifting range from 1550 to 380 nm are demonstrated 25 . The bandwidth of the above CLC planar optics is restricted to ∼100 nm.…”

“…The OV generator, beam deflector, and off-axis lens with a customizable working band in the shifting range from 1550 to 380 nm are demonstrated. 25 The bandwidth of the above CLC planar optics is restricted to ∼100 nm. Additionally, the geometric phase is selectively encoded to the circular polarization (CP) with the same handedness as the helical structure, hindering the practical application of such devices.…”

Bistable Cholesteric Liquid Crystal Films with Excellent Electro-Optical Performance and Spacing Stability for Reflective Displays

“…7,8 Consequently, CLCs have been extensively studied and widely used in the fields of displays, 9−17 OLEDs, 18 light shutters, 19−23 gratings, 24,25 light filters, 26 smart glasses, 27 anticounterfeiting labels, 28 optical vortex processors, 29 and spatial phase modulators. 30 A bistable liquid crystal writing board is a portable display device based on CLCs, with the advantages of energy saving, portability, and flexibility. 31 When pressure is applied to the surface of the writing board, the CLCs convert from a focal cone texture to a planar reflective texture, which in turn displays the image.…”

“…This is attributed to the fact that the selective reflection bandwidth Δλ = Δ n × p of the CLCs is located just in the visible-light region, where Δ n = n e – n o is the birefringence of the liquid crystal (LC), n e is the extraordinary light refractive index, n o is the ordinary light refractive index, and p is the pitch of the CLCs . In addition, due to the ability to maintain a stable optical state after removing external stimuli, bistable electro-optical devices based on CLCs show the advantages of ultralow power consumption, long image storage time at zero electric field, and no backlight. , Consequently, CLCs have been extensively studied and widely used in the fields of displays, − OLEDs, light shutters, − gratings, , light filters, smart glasses, anticounterfeiting labels, optical vortex processors, and spatial phase modulators …”