Revealing the Wonder of Natural Photonics by Nonlinear Optics

Nano-optics explores linear and nonlinear phenomena at the nanoscale to advance fundamental knowledge about materials and their interaction with light in the classical and quantum domains in order to develop new photonics-based technologies. In this perspective article, we review recent progress regarding the application of nonlinear optical methods to reveal the links between photonic structures and functions of natural photonic geometries. Furthermore, nonlinear optics offers a way to unveil and exploit the complexity of the natural world for developing new materials and technologies for the generation, detection, manipulation, and storage of light at the nanoscale, as well as sensing, metrology, and communication

Linear and nonlinear optical response from Cicadas transparent wings

The wings of some insect species are known to fluoresce under illumination by ultraviolet light. Their fluorescence properties are, however, not comprehensively documented. In this presentation, the optical properties of unknown fluorophores naturally occurring within Cicadas transparent wing, were investigated using both linear and nonlinear optical (NLO) methods, including one- and two-photon fluorescence and second harmonic generation (SHG)

Investigation of the second hyperpolarizability of Ru-alkynyl complexes by z-scan and nonlinear scattering

Present-day methods for determining the performance of third-order nonlinear optical materials include Z-scan, degenerate four-wave mixing and third-harmonic generation (THG). All these techniques possess severe drawbacks; for example, in THG, since all media (air and glass walls of the cell) present a third-order effect, eliminating these contributions requires careful, complex analysis or use of vacuum chambers. We have developed nonlinear scattering as a sensitive, straightforward technique for determining the second hyperpolarizability of samples in solution. Herein, we will for the first time show the applicability of the technique to measure organometallic Ru-complexes, optimized for high nonlinear responses. The investigated compounds showed a significant second hyperpolarizability |γ|, ranging from 1.1 for the least efficient to 2.8 ∙ 10-33 esu for the most efficient molecule, and comparable to fullerene C60 in thin films. It was deemed infeasible to extract hyperpolarizabilities using a high-frequency femtosecond laser source by a modified z-scan setup, which, in contrast to nonlinear scattering, could not account for the high degree of thermal lensing present in the investigated compoundsWe thank the Fund for Scientific Research-Flanders (PhD fellowship N.V.S) and the Australian Research Council for support. N.A.A.S thanks the Ministry of Higher Education of Malaysia and the National Defence University of Malaysia for a PhD scholarship

Effect of operational parameters on the performance of a magnetic responsive biocatalytic membrane reactor

In this work, the performance of an innovative magnetic responsive biocatalytic membrane reactor (BMRSP) has been investigated under various operational parameters. In particular, feed concentrations, flow rates across the bed, temperature and amount of biocatalytic bead were varied to probe the flow-dependent transport and kinetic properties of the reaction and the subsequent hydrolytic performance of the BMRSP. The rate of fouling for the BMRSP was always lower than a corresponding control system. For a given enzymatic concentration, a constant foulant hydrolyzing capacity is identified. At 3 g/m2 pectinase containing bionanocomposites, the BMRSP hydrolytic efficiency was 1.5 g/m2 h. This efficiency was further increased by increasing the amount of bionanocomposites per membrane area. This further allowed the BMRSP to hydrolyze higher loads of foulants while keeping a low if not zero increase in TMP over time at constant flux. Identification of an optimal operating condition laid the platform for continuous operation of the BMRSP over 200 h, without visible transmembrane pressure drift while maintaining constant flux. Product assay in the permeate gave constant value in the entire duration, i.e., no enzymatic activity decay owing to stable enzyme immobilization and no leakage through the pores of the membrane owing to the synergistic magnetic interaction between the magnetic membrane and magnetic bionanocomposites. The obtained stability over a broad range of operational parameters and sustainable performance over long period gives a high prospect to the newly developed BMRSP to be utilized in continuous biocatalysis and separation, thereby significantly improved process efficiency

Controlled partial interpenetration in metal–organic frameworks

International audienceInterpenetration, the entwining of multiple lattices, is a common phenomenon in metal–organic frameworks (MOFs). Typically, in interpenetrated MOFs the sub-lattices are fully occupied. Here we report a family of MOFs in which one sub-lattice is fully occupied and the occupancy level of the other can be controlled during synthesis to produce frameworks with variable levels of partial interpenetration. We also report an ‘autocatenation’ process, a transformation of non-interpenetrated lattices into doubly interpenetrated frameworks via progressively higher degrees of interpenetration that involves no external reagents. Autocatenation maintains crystallinity and can be triggered either thermally or by shear forces. The ligand used to construct these MOFs is chiral, and both racemic and enantiopure partially interpenetrated frameworks can be accessed. X-ray diffraction, nonlinear optical microscopy and theoretical calculations offer insights into the structures and dynamic behaviour of these materials and the growth mechanisms of interpenetrated MOFs

Unveiling the nonlinear optical response of Trictenotoma childreni longhorn beetle

The wings of some insect species are known to fluoresce under illumination by ultraviolet light. Their fluorescence properties are however, not comprehensively documented. In this article, the optical properties of one specific insect, the Trictenotoma childreni yellow longhorn beetle, were investigated using both linear and nonlinear optical (NLO) methods, including one- and two-photon fluorescence and second harmonic generation (SHG). These three distinct optical signals discovered in this beetle are attributed to the presence of fluorophores embedded within the scales covering their elytra. Experimental evidence collected in this study indicates that the fluorophores are non-centrosymmetric, a fundamental requirement for SHG. This study is the first reported optical behavior of this type in insects. We described how NLO techniques can complement other more convenient approaches to achieve a more comprehensive understanding of insect scales and integument properties