Abdinewman1846

Circular dichroism spectroscopy is frequently used to characterize the chiral biomolecules by measuring the absorption spectra contrast between the left-handed circularly polarized light and the right-handed circularly polarized light. Compared with biomolecules, chiral metal plasmonic nanostructures also produce a strong circular dichroism response in the range of near-infrared. However, due to the large damping rate, the non-adjustable resonant frequency of the conventional metals, the applications of chiral metal plasmonic nanostructures in the fields of photoelectric detection and chemical and biochemical sensing are restricted. Here, we present a chiral graphene plasmonic Archimedes' spiral nanostructure that displays a significant circular dichroism response under the excitation of two polarizations of circularly polarized light. By manipulating the material and geometric parameters of the Archimedes' spiral, the stronger circular dichroism responses and modulation of the resonant wavelength are achieved. The optimized plasmonic nanostructure has outstanding refractive index sensing performance, where the sensitivity and figure of merit reach 7000nm/RIU and 68.75, respectively. Our proposed chiral graphene plasmonic Archimedes' spiral nanostructure might find potential applications in the fields of optical detection and high performance of index sensing.We simulate Kerr and plasma nonlinearities in a hollow-core fiber to show how plasma effects degrade the output pulse. Our simulations predict the plasma effects can be avoided entirely by implementing divided-pulse nonlinear compression. In divided-pulse nonlinear compression, a high-energy pulse is divided into multiple low-energy pulses, which are spectrally broadened in the hollow-core fiber and then recombined into a high-energy, spectrally broadened pulse. With the plasma effects overcome, spectral broadening can be scaled to larger broadening factors and higher pulse energies. We anticipate this method will also be useful to scale spectral broadening in gas-filled multipass cells.Metasurfaces have shown promising potentials in shaping optical wavefronts while remaining compact compared to bulky geometric optics devices. The design of meta-atoms, the fundamental building blocks of metasurfaces, typically relies on trial and error to achieve target electromagnetic responses. This process includes the characterization of an enormous amount of meta-atom designs with varying physical and geometric parameters, which demands huge computational resources. In this paper, a deep learning-based metasurface/meta-atom modeling approach is introduced to significantly reduce the characterization time while maintaining accuracy. Based on a convolutional neural network (CNN) structure, the proposed deep learning network is able to model meta-atoms with nearly freeform 2D patterns and different lattice sizes, material refractive indices and thicknesses. Moreover, the presented approach features the capability of predicting a meta-atom's wide spectrum response in the timescale of milliseconds, attractive for applications necessitating fast on-demand design and optimization of a meta-atom/metasurface.We show how photoexcitation of a single plasmonic nanoparticle (NP) in solution can create a whispering-gallery-mode (WGM) droplet resonator. Small nano/microbubbles are initially formed by laser-induced heating that is localized by the plasmon resonance. Fast imaging shows that the bubbles collect and condense around the NP and form a droplet in the interior of the bubble. Droplets containing dye generated lasing modes with wavelengths that depend on the size of the droplet, refractive index of the solvent, and surrounding environment, matching the behavior of a WGM. We demonstrated this phenomenon with two kinds of Au NPs in addition to TiN NPs and observed cavity diameters as small as 4.8 µm with a free spectral range (FSR) of 12 nm. These results indicate that optical pumping of plasmonic NPs in a gain medium can generate lasing modes that are not directly associated with the plasmon cavity but can arise from its photophysical processes. This process may serve as a method to generate plasmonic/photonic optical microcavities in solution on demand at any location in a solvent using free-space coupling in/out of the cavity.We present sequentially timed all-optical mapping photography (STAMP) with a slicing mirror in a branched 4f system for an increased number of frames without sacrificing pixel resolution. The branched 4f system spectrally separates the laser light path into multiple paths by the slicing mirror placed in the Fourier plane. Fabricated by an ultra-precision end milling process, the slicing mirror has 18 mirror facets of differing mirror angles. We used the boosted STAMP to observe dynamics of laser ablation with two image sensors which captured 18 subsequent frames at a frame rate of 126 billion frames per second, demonstrating this technique's potential for imaging unexplored ultrafast non-repetitive phenomena.This paper presents our research on quantum well intermixing (QWI) of InP-based AlGaInAs/AlGaInAs multi-quantum wells using impurity-free vacancy-disordering (IFVD) and the QWI mask proximity effect and its application in the design and fabrication of a teardrop laser. Using a Si3N4 film deposited by plasma-enhanced chemical vapor deposition (PECVD) as a QWI promoter mask and annealing under 700°C for 2 minutes, a 70 nm wavelength blue shift of a FP laser is achieved using InP-based AlGaInAs quantum well laser material. It is found that a 5 µm separation is needed between the QWI mask edges and the non-QWI area during the QWI process. Based on the QWI technique and proximity effect, the designed and fabricated teardrop laser demonstrated continuous wave (CW) lasing above 40 mA and single frequency operation with a side mode suppression ratio of 32.6 dB at 77.3 mA.As newly emerging nanomaterials, topological insulators with unique conducting surface states that are protected by time-reversal symmetry present excellent prospects in electronics and photonics. The active control of light absorption in topological insulators are essential for the achievement of novel optoelectronic devices. Herein, we investigate the controllable light absorption of topological insulators in Tamm plasmon multilayer systems composed of a Bi1.5Sb0.5Te1.8Se1.2 (BSTS) film and a dielectric Bragg mirror with a graphene-involved defect layer. The results show that an ultranarrow electromagnetically induced transparency (EIT)-like window can be generated in the broad absorption spectrum. Based on the EIT-like effect, the Tamm plasmon enhanced light absorption of topological insulators can be dynamically tuned by adjusting the gate voltage on graphene in the defect layer. find more These results will pave a new avenue for the realization of topological insulator-based active optoelectronic functionalities, for instance light modulation and switching.