Light-harvesting structures in natural photosynthetic organelles, such as those in purple bacteria, consist of light-responsive chromophores in densely packed antennae systems with organized nanostructures. Inspired by these biological systems, we've created organic materials with densely packed J-aggregates in a polymeric matrix, mimicking the optical role of a protein scaffold. These materials exhibit tunable polaritonic properties from visible to infrared. Drawing from the structure of light-harvesting complexes in purple bacteria, we've studied interactions between light and J-aggregate-based nanorings. Electromagnetic simulations show these nanorings act as resonators, confining light beyond subwavelength scales. These findings enable bio-inspired building components for metamaterials spanning the visible to infrared spectrum in an all-organic platform, offering a fresh perspective on nanoscale light-matter interactions in densely packed organic materials in biological organisms, including photosynthetic organelles.
In this work, we prepare plexcitonic nanoparticles composed by plasmonic nanoparticles, Au@Ag@mSiO2 nanorattles, and J-aggregates of TDBC cyanine dye to be used as ultra-efficient SERS-tags. The methodology used here allowed us to improve the colloidal stability of the plexcitonic nanoparticles. The optical properties have been characterised by UV-vis-NIR and Surface-Enhanced Raman Scattering (SERS) spectroscopies. Besides, finite-difference time-domain (FDTD) calculations revealed that the electromagnetic field is strongly confined into the J-aggregate deposited over the surface of the plasmonic nanoparticle at wavelengths near the upper plexciton. However, for the lower plexciton mode, the electromagnetic field decays through the J-aggregate/water interface. In summary, the plexcitonic nanoparticles showed high SERS efficiency for 532 nm and 633 nm laser lines, even reaching single-nanoparticle detection. The results obtained showed us the significance of strong coupling effect which might lead new possibilities for ultrasensitive biosensing and bioimaging.
Bioinspired photonics is rapidly advancing, leveraging nature's light-managing mechanisms to enhance sustainability, resilience, and processability in nanophotonic applications. A recent breakthrough in the field is the discovery of iridoplast, a chloroplast type with an efficient Bragg reflector structure that boosts light absorption through slow light effects. In this paper, we showcase how all-organic, metal-free photonic structures inspired by iridoplast exhibit optical properties that are thought to be unique to metals or complex oxide compositions.
Firstly, we demonstrate that by replicating iridoplast using organic materials, a photonic crystal with Near-Zero-Index (NZI) properties is produced. We show experiments where the organic dye introduces strong absorptions, resulting in an NZI response and photonic stopbands that enhance light absorption in the VIS. Secondly, we show that, with the same materials but a different structure, it's possible to enable Optical Tamm States. Our results demonstrate that photosynthesis is a promising and yet poorly explored source of inspiration for sustainable photonics.
The increasing demand for precise chemical and biological sensing has led to the development of highly efficient plasmonic optical fiber sensors. Therefore, it is essential to optimize and match the operating wavelength region of both the optical fiber configuration and localized surface plasmon resonance of nanoparticles (NPs). This can be achieved by developing NPs that can reach resonance at near-infrared wavelengths, where refractive index sensitivity is enhanced, and silica optical fibers have lower losses. High aspect-ratio bimetallic Au@Ag nanorods and different side-polished fiber structures are tested using numerical simulations. The selected optical fiber configuration was based on a side- polished fiber with a 1 mm polished section. It is compared power losses and power at the NP interface for two configurations: a step-index single-mode fiber (SMF) with core/cladding diameters of 8.2/125 µm and a multimode graded-index fiber (GIF) with 62.5/125 µm at various polishing depths. The results showed that the best performance for both configurations was achieved at similar polishing depths, namely 59.5 and 55.2 µm for the SMF and GIF, respectively. The optical impact of retardation effects due to the proximity with the fiber structure were also observed, which caused a reduction in sensitivity from 1750 nm/RIU to 1500 nm/RIU and a red-shift of
The transport of quantum states without loss of "coherence" is extremely important for realizing quantum information systems. Quantum effects have been demonstrated in exotic systems, such as cold atoms suspended in magnetic fields, but these systems are extremely challenging to realise. In this work we will translate this work into the chemical domain, using thin films of "J-aggregates". These J-aggregates are quantum many-body systems characterized by the sharing of excitonic states over two or more molecules. This novel organic quantum soft-matter platform can confine the light at the nanoscale taking the advantages of supramolecular chemistry to design properties on demand.
Plasmonic materials are well stablished and used in fields like biomedicine or energy harvesting due to their exceptional optical properties. One of the most interesting characteristics of plasmonic nanoparticles is their ability to confine light at the nanoscale. Nevertheless, such behaviour can also be found in some non-metallic materials as in organic-excitonic materials based on J-aggregates. Herein, we evaluate the synthetic route to obtain colloidal dispersions of excitonic core-shell nanoparticles that can mimicking plasmonic behaviour.
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