•Two-dimensional optical beam-steering of a band-edge liquid crystal laser.•No variation in wavelength; minimal impact on the intensity.•Liquid-crystal-polymer-based configuration and dynamic ...electrical control.•Demonstration of simulating imperfections in the polarisation grating structure.
In this paper, we demonstrate dynamic optical beam-steering of a band-edge chiral nematic liquid crystal (LC) laser that does not involve any change in the configuration of the helical structure. This beam-steering is achieved by exploiting the circular polarisation of the LC laser in combination with tuneable nematic LC phase shifters and fixed polarisation gratings. Experimental results are presented, showing the optical steering of the LC laser emission to four separate discrete spatial positions and, using simulations based on Jones calculus, we explain the appearance and relative intensities of other minor spots that appear around the primary beam. Compared with other approaches of beam-steering an LC laser, this method does not result in an alteration of the laser wavelength, does not change the internal cavity structure of the laser, and has a minimal impact on the intensity of the laser emission. In addition, the whole system (except for the solid-state pump source) is comprised of thin films that are either liquid crystalline or polymers, which provides a tangible route towards a more compact and integrated optically steerable LC laser.
In this study, lump, lump one-strip, lump two-strip, rogue wave, manifold periodic type exact solutions are produced via appropriate transformation scheme by taking into account the Kerr Law ...properties of the model defining nematic liquid crystals. The various transformations are considered in the form containing positive quadratic functions, trigonometric, exponential and hyperbolic functions respectively. In addition we have generated Ma-breather (MB), Kuznetsov-Ma breather (KMB) and its relating rogue wave solutions for proposed model. The resulting solutions of the model play an significant character in the energy transport in soliton molecules in liquid crystals. Furthermore, the wave behaviours for diverse values of constants in the attained exact solutions are explained.
Circularly polarized light (CPL) is central to photonic technologies. A key challenge lies in developing a general route for generation of CPL with tailored chiroptical activity using low‐cost raw ...materials suitable for scale‐up. This study presents that cellulose films with photonic bandgaps (PBG) and left‐handed helical sense have an intrinsic ability for circular polarization leading to PBG‐based CPL with extraordinary |g | values, well‐defiend handedness, and tailorable wavelength by the PBG change. Using such cellulose films, incident light ranging from near‐UV to near‐IR can be transformed to passive L‐CPL and R‐CPL with viewing‐side‐dependent handedness and |g | values up to 0.87, and spontaneous emission transformed to R‐CPL emission with |g | values up to 0.68. Unprecedented evidence is presented with theoretical underpinning that the PBG effect can stimulate the R‐CPL emission. The potential of cellulose‐based CPL films for polarization‐based encryption is illustrated. The evaporation‐induced self‐assembly coupled with nanoscale mesogens of cellulose nanocrystals opens new venues for technological advances and enables a versatile strategy for rational design and scalable manufacturing of organic and inorganic CPL films for photonic applications.
Chiral photonic cellulose films have intrinsic ability to generate and manipulate circularly polarized light (CPL) with extraordinary |g | values in a broad spectral regime. The CPL handedness is well defined, and the wavelength control is simple to realize. Photonic bandgap effects cause stimulated CPL. It presents a versatile and scalable strategy for customized CPL materials using renewable cellulose for photonic applications.
This paper is concerned with the nonhomogeneous incompressible model for the nematic liquid crystals in a smooth bounded domain Ω⊂R3 with vacuum being allowed. Compared with the results before, we ...proof the local existence of a unique strong solution without assuming any compatibility condition to the initial data.
We study equilibria of a discrete Landau–de Gennes energy functional for nematic liquid crystals in the small intersite coupling regime. We consider the 3 × 3 Q−tensor case in finite lattices and ...graphs and show necessary and sufficient conditions for the continuation of equilibria of the decoupled discrete Landau–de Gennes system. The main tools are continuation and symmetry arguments. The theory connects the Landau–de Gennes equilibria to equilibria of a generalized discrete Oseen–Frank energy and also implies that the gradient flow of the decoupled Landau–de Gennes energy has normally hyperbolic invariant submanifolds.
•Study equilibria of discretized Landau–de Gennes energy in case of 3 × 3 Q-tensor in finite graphs.•Analyze geometry of critical sets of discretized Landau–de Gennes energy in decoupled case.•Show necessary and sufficient conditions for continuation of static solutions of decoupled system.•Show existence of normally hyperbolic invariant sets in gradient flow.
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•THz broadband amplitude modulation of flexible FNLC materials under magnetic field.•Using microfluidic chip to reduce the absorption of THz waves in H2O.•Increasing magnetic fluid ...maximum MD to 78% by using topological defects of LC.•The experimental results lay a foundation for liquid film THz modulator.
In recent years, solid state terahertz (THz) modulators have obtained rapid progress with the widespread use of two-dimensional (2D) materials in the field of THz; however, challenges remain in preparing flexible THz modulators. In this study, flexible ferromagnetic nematic materials were prepared by doping thermotropic nematic liquid crystals 5CB into magnetic fluids, and the influence of water was reduced by a self-made cyclic olefin copolymer (COC) microfluidic chip. THz modulation characteristics of magnetic fluid and ferromagnetic nematic liquid crystal (FNLC) under the induction of external magnetic field were compared using a THz time domain spectroscopy system. Under the action of a 91 mT magnetic field, the magnetic fluid has a maximum modulation depth (MD) of 54%. Under the same magnetic field, the maximum MD of the FNLC materials increase to 78% because of the rearrangement of Fe3O4 nanoparticles induced by the topological defect of the liquid crystal. We demonstrate that the magneto-optical effect is significantly enhanced in the ferromagnetic nematic liquid crystal hybrid system. This strategy of doping thermotropic nematic liquid crystals to enhance the magneto-optical effect has great potential for THz filtering, modulation, and sensing applications.
Chiral Photonic Polymers
In article number 2103309, Albertus P. H. J. Schenning, Michael G. Debije, and co‐workers show that using direct ink writing, unconventional chiral nematic objects can be ...generated, which show a bright iridescent color from normal incidence, or only from sharp angles of observation depending on the writing speed. The cover is a polarized optical microscopy image showing a detail from the free‐standing Morpho‐inspired print.
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