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Adaptive optics (AO) is a powerful tool used in a wide range of research areas spanning from aerospace to microscopy. To date, AO has largely been applied to optical phase aberration correction, with recent advances extending to include the vectorial properties of light. However, intensity errors widely exist in optical systems, yet their associated correction methods are still very much in their infancy. Here, we propose a new adaptive optics method that is termed intensity adaptive optics (I-AO), which features a dual-feedback loop for intensity aberration correction that addresses both intensity uniformity and the overall intensity. We demonstrate that I-AO can operate in both sensor-based and sensorless regimes and validate its feasibility by quantitatively analysing the quality of the focus of an aberrated optical system. This technique expands the AO toolkit, broadens its scope of application, and opens a new avenue for next-generation AO innovations.

Replicating the microstructure and near-unity excitation energy transfer efficiency in natural light-harvesting complexes (LHCs) remains a major challenge for synthetic energy-harvesting devices. Biological photosynthesis can spontaneously regulate the active ensembles of involved energy absorbing and funnelling chlorophyll-containing proteins in response to fluctuating sunlight. Here we utilize liquid crystalline (LC) ordering to fine-tune the polymer packing and photophysical properties in liquid crystalline conjugated polymer (LCCP) films for LHC biomimicry and optimizing photoluminescence quantum efficiency (PLQE). We show that the long-range orientational ordering present in a LC phase of poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT) stabilizes a small fraction of randomly-oriented F8BT nanocrystals dispersed in an amorphous matrix of disordered F8BT chains, hence resembling a self-doped host-guest system whereby excitation energy funnelling and PLQE are reinforced significantly by three-dimensional donor-to-acceptor Forster resonance energy transfer (FRET) and dominant intrachain emission in the nano-crystalline acceptor. Furthermore, the photoalignment of nematic F8BT layers is combined to fabricate long-sought large-area-extended monodomains which exhibit >60% crystallinity and ~20 nm-long interchain packing order, whilst also promoting linearly polarized emission, a new band-edge absorption species, and an extra emissive interchain excited state. Our micro-PL spectral results support the feasibility of making use of self-doped F8BT nematic films for bio-mimicry of certain structural basis and light-harvesting properties of naturally occurring LHCs.

Optical Skyrmions have many important properties that make them ideal units for high-density data applications, including the ability to carry digital information through a discrete topological number and the independence of spatially varying polarization to other dimensions. More importantly, the topological nature of the optical Skyrmion heuristically suggests a strong degree of robustness to perturbations, which is crucial for reliably carrying information in noisy environments. However, the study of the topological robustness of optical Skyrmions is still in its infancy. Here, we quantify this robustness precisely by proving that the topological nature of the Skyrmion arises from its structure on the boundary and, by duality, is therefore resilient to complex perturbations provided they respect the relevant boundary conditions of the unperturbed Skyrmion. We then present experimental evidence validating this robustness in the context of paraxial Skyrmion beams against different polarization aberrations. Our work provides a framework for handling various perturbations of Skyrmion fields and offers guarantees of robustness in a general sense. This, in turn, has implications for applications of the optical Skyrmion where their topological nature is exploited explicitly, and, in particular, provides an underpinning for the use of Skyrmions in optical communications and photonic computing.

Sapphire fiber can withstand around 2000{\deg}C, but it is multimoded, giving poor precision sensors. We demonstrate a single-mode sapphire fiber Bragg grating temperature sensor operating up to 1200{\deg}C. The repeatability above 1000{\deg}C is within {\pm}0.08%., Comment: 4 Pages, 5 Figures

Skyrmions are topologically protected quasiparticles, originally studied in condensed-matter systems and recently in photonics, with great potential in ultra-high-capacity information storage. Despite the recent attention, most optical solutions require complex and expensive systems yet produce limited topologies. Here we demonstrate an extended family of quasiparticles beyond normal skyrmions, which are controlled in confined photonic gradient-index media, extending to higher-order members such as multiskyrmions and multimerons, with increasingly complex topologies. We introduce new topological numbers to describe these complex photonic quasiparticles and propose how this new zoology of particles could be used in future high-capacity information transfer. Our compact creation system lends integrated and programmable solutions of complex particle textures, with potential impacts on both photonic and condensed-matter systems for revolutionizing topological informatics and logic devices.

Organic photoswitchable molecules have struggled in solid state form to fulfill their remarkable potential, in terms of photoswitching performance and long-term stability when compared to their inorganic counterparts. We report the concept of non-electron deficient host's surface with optimal porosity and hydrophobicity, as a priori strategy to design photoefficient organic solid-state photochromic materials with outstanding mechanical robustness. When exposed to a light stimulus including natural sunlight, the photoswitchable nanocomposite changes color promptly and reversibly, in a matter of seconds along with excellent photo-fatigue resistance, which are on a par with inorganic photochromes. Exemplars of commercially viable prototypes that are optically clear, comprising smart windows, complex photochromic sculptures, and self-erasing rewritable devices, were engineered by direct blending with resilient polymers; particularly, the use of high-stiffness polymer (> 2 GPa) is no longer an insurmountable challenge. Finally, photochromic films with anticounterfeiting features could be manufactured through precision inkjet printing of nanocrystals., Comment: 12 pages, 5 figures, Supplementary Information

Ultra-sensitive and highly selective iodine gas sensors play a crucial role during the nuclear radiation leak for a timely detection and mitigation of pollution, ensuring the safety of a vast number of operators and subsequent integrity of the facility. Herein, we rationally designed a metal-organic framework (MOF) that exhibits an outstanding performance with an almost billion-fold enhancement in the electrical response due to its optimized hydrophobicity, which allows the easy migration of iodine molecules though the channels and the presence of suitable interaction sites, temporarily anchoring the target molecule for ultra-trace sensing. The prototype sensor tested in demanding environments demonstrates its high selectivity, ultra-trace parts per billion (ppb)-level sensitivity, good reversibility, and a very fast response time even at high frequencies compared to existing adsorbents, including commercially available materials. Further, the iodine sensing at the atomic level was studied in detail by measuring the electrical response of a single crystal and, the optimal thickness of the MOF layer was identified for an industrially-viable prototype sensor by using inkjet printing. In a wider perspective, we propose a general strategy towards electrically efficient sensing materials with hybrid functionalities for engineering high-sensitivity iodine sensors for a safe and sustainable future., Comment: 14 Pages, 5 Figures, 1 Supporting Information (32 pages)

We present here the inscription of single-mode waveguides with Bragg gratings in sapphire. The waveguide Bragg gratings have a novel multi-layer depressed cladding design in the 1550 nm telecommunications waveband. The Bragg gratings have a narrow bandwidth (<0.5 nm) and have survived annealing at 1000{\deg}C. The structures are inscribed with femtosecond laser direct writing, using adaptive beam shaping with a non-immersion objective. A single-mode sapphire fiber Bragg grating is created by writing a waveguide with a Bragg grating within a 425 {\mu}m diameter sapphire optical fiber, providing significant potential for accurate remote sensing in ultra-extreme environments., Comment: Submitted to Optica 12 November 2021