Integrated silicon photonics OFDR system for high-resolution distributed measurements based on Rayleigh backscattering

Optical frequency domain reflectometry (OFDR) has high spatial resolution and measurement accuracy, driving its popularity in various fields. Integration of OFDR technology has made it accessible, cost-effective and deployable in many applications, including battery management and photonic integrated circuits. An integrated OFDR system based on Rayleigh backscattering and silicon photonics technology on an SOI platform has been developed for the first time. The system's simplified configuration was simulated, fabricated and characterized in detail, achieving an experimental spatial resolution of 8.28 μm, matching the theoretical level. This system shows high potential for sensing, monitoring and detection where precise spatial information is crucial. OFDR's accessibility and high performance in distributed measurements make it a promising technology for future advancements

Manipulating the Subcellular Localization and Anticancer Effects of Benzophenothiaziniums by Minor Alterations of N-Alkylation

Cationic, water-soluble benzophenothiaziniums have been recognized as effective type I photosensitizers (PSs) against hypoxic tumor cells. However, the study of the structure–property relationship of this type of PS is still worth further exploration to achieve optimized photodynamic effects and minimize the potential side effects. Herein, we synthesized a series of benzophenothiazine derivatives with minor N-alkyl alteration to study the effects on the structure–property relationships. The cellular uptake, subcellular organelle localization, reactive oxygen species (ROS) generation, and photocytotoxicity performances were systematically investigated. NH2NBS and EtNBS specifically localized in lysosomes and exhibited high toxicity under light with a moderate phototoxicity index (PI) due to the undesirable dark toxicity. However, NMe2NBS with two methyl substitutions accumulated more in mitochondria and displayed an excellent PI value with moderate light toxicity and negligible dark toxicity. Without light irradiation, NH2NBS and EtNBS could induce lysosomal membrane permeabilization (LMP), while NMe2NBS showed no obvious damage to lysosomes. After irradiation, NH2NBS and EtNBS were released from lysosomes and relocated into mitochondria. All compounds could induce mitochondria membrane potential (MMP) loss and nicotinamide adenine dinucleotide phosphate (NADPH) consumption under light to cause cell death. NMe2NBS exhibited remarkable in vivo photodynamic therapy (PDT) efficacy in a xenograft mouse tumor (inhibition rate, 89%) with no obvious side effects. This work provides a valuable methodology to investigate the structure–property relationships of benzophenothiazine dyes, which is of great importance in the practical application of PDT against hypoxia tumor cells

Dual-Band Modulation of Visible and Near-Infrared Light Transmittance in an All-Solution-Processed Hybrid Micro–Nano Composite Film

Smart windows with controllable visible and near-infrared light transmittance can significantly improve the building’s energy efficiency and inhabitant comfort. However, most of the current smart window technology cannot achieve the target of ideal solar control. Herein, we present a novel all-solution-processed hybrid micronano composite smart material that have four optical states to separately modulate the visible and NIR light transmittance through voltage and temperature, respectively. This dual-band optical modulation was achieved by constructing a phase-separated polymer framework, which contains the microsized liquid crystals domains with a negative dielectric constant and tungsten-doped vanadium dioxide (W-VO₂) nanocrystals (NCs). The film with 2.5 wt % W-VO₂ NCs exhibits transparency at normal condition, and the passage of visible light can be reversibly and actively regulated between 60.8% and 1.3% by external applied voltage. Also, the transmittance of NIR light can be reversibly and passively modulated between 59.4% and 41.2% by temperature. Besides, the film also features easy all-solution processability, fast electro-optical (E-O) response time, high mechanical strength, and long-term stability. The as-prepared film provides new opportunities for next-generation smart window technology, and the proposed strategy is conductive to engineering novel hybrid inorganic–organic functional matters