In optics, which is evolving toward downsizing, integration, and many functionalities, wavefront control is crucial. Plasmonic or dielectric artificial nanostructures are arranged in an incredibly thin plane to form a metasurface. It substantially advances the development of contemporary optics by overcoming the bulky size of conventional deflective and diffractive optics based on propagation phase accumulation. On the basis of spatially customising the geometries of resonators, distinct phase diagrams have recently been individually encoded to two orthogonal polarisation components. In a variety of industries, including optical computers, optical communications, virtual/augmented reality, and holographic displays, new methods for spin-decoupled spatial light modulation with broadband high efficiency and affordable volume manufacturing are widely desired. Due to their inherent broadband birefringence and diverse externalfield reactivity, liquid crystals (LCs) are regarded as yet another top contender for planar optics. A chiral helical structure is seen in cholesteric LC (CLC). CLC self-assembles into ordered chiral superstructures and demonstrates distinct properties in a photopatterned planarly aligned cell. All LC-based geometric phase optics up to this point has only been able to work with spin-coupled conjugated phases. Thus, the development of planar optics with spin-decoupled functionalities is urgently needed and is anticipated to unleash the multifunctionality of contemporary optics.
In a new study published in the Journal Advanced Science Nanjing University scientists: Dr. Rui Yuan, Chun-Ting Xu, Han Cao, Yi-Heng Zhang, Guang-Yao Wang, Peng Chen, Yan-Qing Lu, and led by Professor Wei Hu developed a new spin-decoupled transflective spatial light modulation method. The authors demonstrated by piecewise tailoring the helicity of an anisotropic monolayer in the direction of light propagation and customising the space-variant preliminary configurations of helixes in the cross-section of light propagation.
The mirrorsymmetric dual-twist structure and periodic helix make up the monolayer. The working band can be logically tuned by changing the configuration’s twist. By varying the concentration or helical twist power of the chiral dopant, it is possible to change the reflective Bragg band by altering the pitch of the periodic helix. In this case, the transmissive working band is wider than the Bragg reflection band. By including bigger birefringent LCs, gradient-variant helix, and stacking multipitch helical layers, this problem can be effectively handled. Any phase diagram can be recorded to alpha and beta in a point-to-point manner because of the photoalignment technique’s high resolution and good flexibility. A compact topological charge scale transflective OAM encoder and decoder is proposed for simple demonstration. Increasing the scale and moving the working wavelength to the telecom band is feasible. As a result, it offers a useful platform for MDM, WDM, and PDM compatible optics. The self-organization capabilities of LCs give rise to the special characteristics of broadband high efficiency and spindecoupled transflective spatial light modulation, making the method simple and effective. A comprehensive framework for creating transflective modulators is described, making everything predictable. It is evident how the configuration of the anisotropic monolayer affects the performance of the produced elements. The new monolithic film method by Professor Wei Hu and colleagues is more compact, material and power efficient than the traditional multifunction with numerous parts. Therefore, the new design has the potential to considerably improve planar optics’ multifunctionality, which has broad potential applications in optical computing, communication, imaging, and information displays.
In summary, Nanjing University scientists used a piecewise-twisted anisotropic monolayer to exhibit spin-decoupled transflective spatial light modulations. A periodic helix and a mirror-symmetric dual-twist shape make up the movie. The space-variant beginning orientations of the helixes can be point-to-point photoaligned to impart any number of phases to the oppositely propagating light that spins have chosen. It satisfies the pressing need in optical informatics by providing a workable approach for MDM, WDM, and PDM compatible optics. Broadband high efficiency and spin-decoupled spatial light modulation are two additional benefits, in addition to being easily and inexpensively manufactured and appropriate for mass manufacturing. This could improve planar optics and lead to many amazing applications including medical imaging to deliver the highest performance and accurate .
Yuan R, Xu CT, Cao H, Zhang YH, Wang GY, Chen P, Lu YQ, Hu W. Spin‐Decoupled Transflective Spatial Light Modulations Enabled by a Piecewise‐Twisted Anisotropic Monolayer. Advanced Science. 2022:2202424.