Virtual Reality (VR) devices present challenges in terms of vergence-accommodation conflict that lead to visual fatigue for the user over time. Fast switchable liquid crystal (LC) lenses which access multiple focal planes can help to overcome this challenge. The response time for Nematic liquid crystals (NLC) is in the millisecond range, while that of ferroelectric liquid crystals (FLC) in the microsecond order. In this paper we look at recent advances in fast switchable liquid crystal lenses using NLC, FLC or both, compare their design and properties with competing technologies. A discussion on the limitations of each design and technology have also been included.

Photoalignment of azobenzenes is one of the most versatile tools for liquid crystal self-assembly for both the surface and bulk. An azobenzene component is homogenously mixed with a liquid crystal and irradiated with polarized visible light. By utilizing a simple two-step exposure method, we can induce photoalignment on the front and back of the liquid crystal sample independently. This back to front alignment, if varying in LC director orientation, translates into a twist through the bulk. In this talk, we discuss the two-step exposure method and how to control the twist as well as introduce characterization methods on twist quantification.

The self-organized periodic micro/nano structure caused by the deformation of the stimulus responsive structure often occurs in anisotropic self-assembled supramolecular systems (such as cholesteric liquid crystal (CLC) systems). However, the long-distance ordering of these structures is often not easy to control. This investigation first demonstrates the manipulation ability of a 1D interference field on the macroscopic orderliness of the resulting 2D microgrid chiral structure via the firstly discovered photopolymerization-induced Helfrich deformation. A pre-built polymer layer in the early stage of photopolymerization continuously thicken to compress the helical pitch of the CLC–monomer region and then induce an internal longitudinal strain, leading to the 2D disordered microgrid structure of Helfrich deformation. A 1D laser interference field can effectively control the post-formed 2D grid microstructure to be arranged in an orderly manner in a macro-exposure area.

We have proved that it is possible to realize optical elements with theory-matching efficiency and practical use, reconfigurable on demand right where and when needed. I will present diffraction optical elements with efficiency equal to the theoretical efficiency can be realized by direct structuring of the surface of a photosensitive polymer, avoiding any further development step. The realized gratings and lenses can be reshaped completely while aligned in the optical setup. Grating periodicity can be changed; lenses focal length can be tuned; one optical element can be morphed into another optical element with completely different optical functionality, without affecting the alignment of the specific optical setup.

Liquid crystal devices are powerful ingredients in virtual reality display research at Facebook Reality Labs (FRL), especially as imaging optical components, thanks to the recent advancements in liquid crystal polarization holograms. Active liquid crystal devices can provide possibilities for dynamic reconfiguration of optical system with fast response time. Liquid crystal lenses or gratings that operate following the principles of diffraction can be designed and fabricated with high diffraction efficiency and high polarization selectivity, while keeping a small form factor. In this paper, we cover how these liquid crystal devices can be applied in virtual reality as imaging optical components.

Blue phase liquid crystals (BPLCs) composed of double twisted cholesteric helixes are promising materials for use in next generation displays, optical components, and photonics applications. However, BPLCs are only observed in a narrow temperature range of 0.5-3 oC and must be stabilized with a polymer network. Here we report on controlling the phase behavior of BPLCs by varying the concentration of an amorphous crosslinker (PETA). LC mixtures without PETA display narrow temperature phase transitions from isotropic to BP-II, BP-I, and cholesteric phases, but the addition of PETA widens temperature window up to 10C. Above 3wt% PETA prevents the formation of BP-II and the mixture instead transitions from isotropic directly to BP-I phase. Blue phase I or II are stabilized using polymer networks via in-situ photopolymerization. Bandwidth broadening and red tuning responses are observed in polymer stabilized BPLCs with 10wt% and 15wt% polymer concentrations when DC voltage is applied.

With the flourish development of artificial intelligence, lasing with tailored features generated by photonic crystal lasers play a more important part in the field of optics and in potential applications such as self-control, LiDAR, telecommunications, and, holography imaging. Here, a self-steering lasing emission from a defect-mode sandwich-like structure consisting of photomechanical deformed azobenzene cholesteric liquid crystal elastomer is demonstrated. The output single-mode lasing emission can be fast steered by UV irradiation to a widely angular tuning range of approximately ±60° with an excitation threshold of Eth = 7.9 ± 0.5 μJ cm−2 per pulse. We envision that this flexible, portable and durable sandwich-like laser system with controllable lasing beam steering and mechanical robustness will open a gate for self-driving vehicle, self-sustained machines and optical devices with the core feature of photomechanical transduction.

In this study, we report the results of confirming the possibility of optical fiber temperature sensors by fabricating cholesteric liquid crystal (CLC) cells combined with optical fibers. The CLC cell was fabricated with a Fabry-Perot etalon using the cross-sections of two optical fiber ferrules as substrates. A 1.2 um wide bandwidth wavelength swept laser was used to measure the spectrum change of the CLC cell according to the applied temperature. The reflection spectra were measured by changing the temperature of the CLC cell at intervals of 2o from 23o to 45o, and it was confirmed that the reflection band shifted discontinuously to a shorter wavelength as the temperature increased.

In this work, the thermal- and photo-reversible symmetrical deformation and structural color changed actuators based on fully-polymerized cholesteric liquid crystal (CLC) polymer beads are demonstrated. A jack-inspired soft microdevice comprising durable fully-polymerized CLC beads by the stand-alone and free of extraction technique is demonstrated to have the unique photo-responsive capabilities of lifting substantially heavy objects and photochromatism via light-triggered symmetric volume expansion of the CLC beads. The desired symmetrical volume expansion with photochromatic property is realized by decreasing the degree of the order parameter, which is caused by the reorientation of the LC director. Such dynamic manipulation of anisotropic geometric deformation of soft materials offer promising infinite possibilities for the applications of smart devices.