1,721,006 research outputs found
Replication Data for: Electrically programmable terahertz diatomic metamolecules for chiral optical control
No full textOptical chirality is central to many industrial photonic technologies including enantiomer identification, ellipsometry-based tomography and spin multiplexing in optical communications. However, a substantial chiral response requires a three-dimensional constituent, thereby making the morphology highly complex to realize structural reconfiguration. Moreover, an active reconfiguration demands intense dosage of external stimuli that pose a major limitation for on-chip integration. Here, we report a low bias, electrically programmable synthetic chiral paradigm with a remarkable reconfiguration among levorotatory, dextrorotatory, achiral, and racemic conformations. The switchable optical activity induced by the chiral conformations enables a transmission-type duplex spatial light modulator for terahertz single pixel imaging. The prototype delivers a new strategy towards reconfigurable stereoselective photonic applications, and opens up avenues for on-chip programmable chiral devices with tremendous applications in biology, medicine, chemistry, and photonics
Replication Data for: A metamaterial analog of the ising model
No full textThe interaction between microscopic particles has always been a fascinating and intriguing area of science. Direct interrogation of such interactions is often difficult. Structured electromagnetic systems offer a rich toolkit for mimicking and reproducing the key dynamics that governs the microscopic interactions, and thus provide an avenue to explore and interpret the microscopic phenomena. In particular, metamaterials offer the freedom to artificially tailor light-matter coupling and to control the interaction between unit cells in the metamaterial array. Here we demonstrate a terahertz metamaterial that mimics spin-related interactions of microscopic particles in a 2D lattice via complex electromagnetic multipoles scattered within the metamaterial array. Fano resonances featured by distinct mode properties due to strong nearest-neighbor interactions are discussed that draw parallels with the 2D Ising model. Interestingly, a phase transition from single Fano resonance to hyperfine splitting of Fano spectrum is observed by manipulating the 2D interactions without applying external magnetic or electric fields, which provides a potential multispectral platform for applications in super-resolution imaging, biosensing, and selective thermal emission. The dynamic approach to reproduce static interaction between microscopic particles would enable more profound significance in exploring the unknown physical world by the macroscopic analogues
Replication Data for: Symmetry-protected dual bound states in the continuum in metamaterials
No full textBound state in the continuum (BIC) is a mathematical concept with an infinite radiative quality factor (Q) that exists only in an ideal infinite array of resonators. In photonics, it is essential to achieve high Q resonances for enhanced light-mater interactions that could enable low-threshold lasers, ultrasensitive sensors, and optical tweezers. Here, we demonstrate dual bound states in the continuum in a subwavelength planar metamaterial array that reveal symmetry-protected polarization-dependent features. The spectral features of dual BICs are experimentally verified in the terahertz domain by breaking the C2 symmetry that invokes a leakage channel in the form of weakly radiating Fano resonance and electromagnetically induced transparency. The radiative Q factors tend to infinity at discrete symmetry-restoring points and obey an inverse square dependence on the structural asymmetry. BICs in metamaterials allow extreme field confinement with small mode volumes, thereby improving the rate of spontaneous emission in the cavity with much larger Purcell factor. In addition, the topological nature enables a robust existence of BICs with a vector beam profile that is ideal for lasing. The symmetry-protected BICs in metamaterials also possess a unique advantage of scalability at different wavelengths for potential applications in sensing, lasing, switching, and spectral filtering
Dataset: Ultrafast all-optical switching of germanium-based flexible metaphotonic devices
No full textDataset for the manuscript "Ultrafast all-optical switching of germanium-based flexible metaphotonic devices"
This research data description should be read and understood in the context of the corresponding manuscript. The figure numbers correspond to the figure numbers of the manuscript and the data corresponds to the data as shown in the figures.</span
Superconducting dual-channel photonic switch
No full textThe mechanism of Cooper pair formation and underlying physics has long occupied the investigation into high temperature (high-Tc ) cuprate superconductors. One of the ways to unravel this is to observe ultrafast response present in charge carrier dynamics of a photoexcited specimen. This results in an interesting approach to exploit the dissipation-less dynamic features of superconductors to be utilized for designing subwavelength photonic devices with extremely low-loss operation. Here, we experimentally demonstrate dual-channel, ultrafast, all-optical switching and modulation between the resistive and the superconducting quantum mechanical phase. The ultrafast phase switching is demonstrated via modulation of sharp Fano resonance of a high-T c Yttrium Barium Copper Oxide (YBCO) superconducting metamaterial device. Upon photoexcitation by femtosecond light pulses, the ultrasensitive cuprate superconductor undergoes dual dissociation-relaxation dynamics, with restoration of superconductivity within a cycle, and thereby establishes the existence of dual switching windows within a timescale of 80 ps. We explored pathways to engineer the secondary dissociation channel which provides unprecedented control over the switching speed. Most importantly, our results envision new ways to accomplish low-loss, ultrafast and ultrasensitive dual channel switching applications that are inaccessible through conventional metallic and dielectric based metamaterials
Dataset for Superconducting dual-channel photonic switch
No full textData for all the plots in the publication
Srivastava, Y. K. et al (2018). Superconducting dual-channel photonic switch. Advanced Materials, 1-8. [1801257].</span
Dataset for Metamaterial analogue of Ising model
No full textDataset supports:
Cong, L. et al. (2018). Metamaterial analogue of Ising model. Advanced Materials. </span
Implementing a Hybrid Method for Shack–Hartmann Wavefront Spots Labeling on FPGA
Full text linkThis paper presents a real-time implementation of a hybrid connected component labeling method for processing the Shack–Hartmann wavefront sensor’s images for an adaptive optics (AO) system. The output image of a wavefront sensor is an image of spots. During the sensor’s operation, it can happen that highly distorted wavefronts (WF) may cause the spots to shift outside of their sub-aperture, which may lead to the reduction of the AO system performance. This article explains the benefits of high-performance computing and parallel processing of a field programmable gate array (FPGA). The objective is to calculate the centroids of these spots. A hybrid labeling method was investigated to fulfill this purpose. First, this method was implemented using a forward and backward scan with a respective mask for each scan. Additionally, a relabeling process is applied after labeling each line, and it is carried out in both directions. After labeling, several processing units were implemented in parallel to calculate centroids. Each unit is responsible for calculating the centroid of one label. The system runs in real time with a latency of one frame, which means the output image is a fusion of a current frame and the centroids of the previous frame. Forward and backward labeling requires a large amount of memory, which is the reason for limiting the investigation to forward labeling only. The forward labeling was successfully implemented, and the centroids were detected under minimum spot distortion conditions. This forward labeling implementation also runs in real time with significant latency reduction to calculate the centroids, which leads to minimizing the overall AO system latency, enabling faster computation and correction in addition to reducing the memory usage to 1% when compared to the forward and backward labeling usage of 81% as an advantage for the hardware implementation
A metamaterial analogue of the Ising model
No full textThe interaction between microscopic particles has always been a fascinating and intriguing area of science. Direct interrogation of such interactions is often difficult. Structured electromagnetic systems offer a rich toolkit for mimicking and reproducing the key dynamics that governs the microscopic interactions, and thus provide an avenue to explore and interpret the microscopic phenomena. In particular, metamaterials offer the freedom to artificially tailor light-matter coupling and to control the interaction between unit cells in the metamaterial array. Here we demonstrate a terahertz metamaterial that mimics spin-related interactions of microscopic particles in a 2D lattice via complex electromagnetic multipoles scattered within the metamaterial array. Fano resonances featured by distinct mode properties due to strong nearest-neighbor interactions are discussed that draw parallels with the 2D Ising model. Interestingly, a phase transition from single Fano resonance to hyperfine splitting of Fano spectrum is observed by manipulating the 2D interactions without applying external magnetic or electric fields, which provides a potential multispectral platform for applications in super-resolution imaging, biosensing, and selective thermal emission. The dynamic approach to reproduce static interaction between microscopic particles would enable more profound significance in exploring the unknown physical world by the macroscopic analogues
Replication Data for: A superconducting dual-channel photonic switch
No full textThe mechanism of Cooper pair formation and its underlying physics has long occupied the investigation into high temperature (high-Tc ) cuprate superconductors. One of the ways to unravel this is to observe the ultrafast response present in the charge carrier dynamics of a photoexcited specimen. This results in an interesting approach to exploit the dissipation-less dynamic features of superconductors to be utilized for designing high-performance active subwavelength photonic devices with extremely low-loss operation. Here, dual-channel, ultrafast, all-optical switching and modulation between the resistive and the superconducting quantum mechanical phase is experimentally demonstrated. The ultrafast phase switching is demonstrated via modulation of sharp Fano resonance of a high-Tc yttrium barium copper oxide (YBCO) superconducting metamaterial device. Upon photoexcitation by femtosecond light pulses, the ultrasensitive cuprate superconductor undergoes dual dissociation-relaxation dynamics, with restoration of superconductivity within a cycle, and thereby establishes the existence of dual switching windows within a timescale of 80 ps. Pathways are explored to engineer the secondary dissociation channel which provides unprecedented control over the switching speed. Most importantly, the results envision new ways to accomplish low-loss, ultrafast, and ultrasensitive dual-channel switching applications that are inaccessible through conventional metallic and dielectric based metamaterials.</span
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