A5075942165- Plasmonic and Surface Plasmon Research
- Mechanical and Optical Resonators
- Thermal Radiation and Cooling Technologies
- Photonic and Optical Devices
- Pickering emulsions and particle stabilization
- Photonic Crystals and Applications
- Micro and Nano Robotics
- Phase-change materials and chalcogenides
- Metamaterials and Metasurfaces Applications
- Glass properties and applications
- Near-Field Optical Microscopy
- nanoparticles nucleation surface interactions
- Nanowire Synthesis and Applications
- Advanced Chemical Physics Studies
- Force Microscopy Techniques and Applications
- Nonlinear Optical Materials Studies
- Orbital Angular Momentum in Optics
- Climate Change and Health Impacts
- Advanced Antenna and Metasurface Technologies
- Liquid Crystal Research Advancements
- Gold and Silver Nanoparticles Synthesis and Applications
- Thin-Film Transistor Technologies
- Spaceflight effects on biology
- Microwave Dielectric Ceramics Synthesis
- Coagulation and Flocculation Studies
Texas Christian University
2022
Lahore Garrison University
2022
Harvard University
2013-2020
Harvard University Press
2017
Laser Science & Technology Centre
1974-2014
University of Illinois Urbana-Champaign
2012-2013
Defence Institute of Physiology and Allied Sciences
1995-2000
Ministry of Defence
1969
Institute of Nuclear Medicine & Allied Sciences
1969
In this paper, we report dispersion-engineered metasurfaces with distinct functionalities controlled by wavelength. Unlike previous approaches based on spatial multiplexing or vertical stacking of metasurfaces, utilize a single phase profile wavelength dependence encoded in the shifters' dispersion. We designed and fabricated multiwavelength achromatic metalens (MAM) focusing for blue (B), green (G), yellow (Y), red (R) light two wavelength-controlled beam generators (WCBG): one focuses...
Hexagonal boron nitride has been proposed as an excellent candidate to achieve subwavelength infrared light manipulation owing its polar lattice structure, enabling excitation of low-loss phonon polaritons with hyperbolic dispersion. We show that strongly hexagonal planar nanostructures can exhibit ultra-confined resonances and local field enhancement. investigate strong light-matter interaction in these nanoscale structures via photo-induced force microscopy, scattering-type scanning...
Abstract We selectively excite and study two new types of phonon-polariton guided modes that are found in hexagonal boron nitride thin flakes on a gold substrate. Such show substantially improved confinement group velocity is hundreds times slower than the speed light, thereby providing way to create slow light mid-infrared range with simple structure does not require nano-patterning. One mode fundamental first Restrahlen band crystals substrate; other equivalent second suspended vacuum. The...
Van der Waals (vdW) heterostructures assembled from layers of two-dimensional materials have attracted considerable interest due to their novel optical and electrical properties. Here, we report a scattering-type scanning near-field microscopy study hexagonal boron nitride on black phosphorus (h-BN/BP) heterostructures, demonstrating the first direct observation in-plane anisotropic phonon polariton modes in vdW heterostructures. Notably, measured anisotropy along armchair zigzag crystal...
We fabricated chemically and shape-anisotropic colloids composed of silica rods coated with gold tips using a multistep process involving electric-field alignment crystallization, microcontact printing, selective metallization. Through direct observation, we found that these "Janus matchsticks" self-assemble into multipods (bi-, tri-, tetrapods) varying coordination number patch angle in aqueous solution.
Polaritons formed by the coupling of light and material excitations enable light-matter interactions at nanoscale beyond what is currently possible with conventional optics. However, novel techniques are required to control propagation polaritons implement first practical devices. Here we report experimental realization polariton refractive meta-optics in mid-infrared exploiting properties low-loss phonon isotopically pure hexagonal boron nitride interacting surrounding dielectric...
Mid-infrared nanoimaging and spectroscopy of two-dimensional (2D) materials have been limited so far to scattering-type scanning near-field optical microscopy (s-SNOM) experiments, where light from the sample is scattered by a metallic-coated atomic force microscope (AFM) tip interacting with material at nanoscale. These experiments recently allowed imaging plasmon polaritons in graphene as well hyperbolic phonon hexagonal boron nitride (hBN). Here we show that high mechanical sensitivity an...
High-operating-temperature direct ink writing (HOT-DIW) of mesoscale architectures that are composed eutectic silver chloride–potassium chloride. The molten undergoes directional solidification upon printing on a cold substrate. lamellar spacing the printed features can be varied between approximately 100 nm and 2 µm, enabling manipulation light in visible infrared range. As service to our authors readers, this journal provides supporting information supplied by authors. Such materials peer...
We investigate the electric field-induced assembly of Janus colloids composed silica rods patterned with gold patches in both side- and tip-coated motifs. These shape chemically anisotropic particles assemble into reconfigurable chains, whose structure depends on patch location, AC field strength, frequency.
Titanium nitride (TiN) has been identified as a promising refractory material for high temperature plasmonic applications such surface plasmon polaritons (SPPs) waveguides, lasers and light sources, near field optics. Such SPPs are sensitive not only to the highly metallic nature of TiN, but also its low loss. We have formed metallic, low-loss TiN thin films on MgO substrates create with resonances between 775-825 nm. Scanning near-field optical microscopy (SNOM) allowed imaging SPP fringes,...
3D-porous anisotropic solids are fabricated by using horizontally and vertically aligned assemblies of silica rods with a length ca. 2 μm diameter 500 nm as templates. Templated materials include examples from metals, semiconductors, ceramics, polymers, Ni, Si, HfO2, PMMA, respectively. By varying the infilling conditions, detailed mesoscale structure degree anisotropy can be controlled. As service to our authors readers, this journal provides supporting information supplied authors. Such...
Explosive crystallization has been observed in thin, unsupported (free) films of amorphous germanium irradiated with a focussed, moderately intense electron beam. Transmission microscopic examination the crystallized show radial dendritic growth followed by annularly arranged periodic surface features. Analysis our results confirm that heat released during to crystalline (a→c) transformation area (∼10 μm) abruptly crystallizes surrounding up ∼120 μm diameter. Origin is consistent...
Guided modes in nanometer thick anisotropic van der Waals materials are experimentally investigated and their refractive indices visible wavelengths extracted. Our method involves near-field scanning optical microscopy of waveguide (transverse electric) surface plasmon polariton magnetic) h-BN/SiO2/Si Ag/h-BN stacks, respectively. We determine the dispersion these use this relationship to extract h-BN flakes. In wavelength interval 550–700 nm, in-plane out-of-plane range 1.98–2.12 1.45–2.12,...
Transmission electron microscope studies of the colloids silver in KCl : Ag crystals show that colloidal particles are spherical shape and have a size distribution among them. Using observed modified optical constants for small metal by Kawabata-Kubo method Mie's theory, calculated shapes bands agree well with band shape.
Antimony films in the thickness range of 50 to 250 Å prepared by vacuum evaporation on single crystal KCL substrates at room temperature show an amorphous structure, which changes readily crystalline form exposure a 40–100-kV electron beam moderate intensity microscope. At nucleation stage thin random orientation crystallization, whereas thicker, nearly continuous assume orientation, with (111)metal‖(001)KCl.
Thle effects of 10-month stay at high altitude (HA) on body composition Indian soldiers mixed ethnic origins with special reference to musculature were investigated. Body density was regrl15sed from skinfold thicknesses and girth measurements. Bone mineral estimated width stature. Muscle X-ray shadow areas upperarm forearm stature correlated massl a regression equation constructed. Analysis data indicated that muscle mass degradqd HA. In group I (height: 4100 m), 1.74 kg degraded generate...
We present high quality factor optical nanoresonators operating in the mid-IR to far-IR based on phonon polaritons van der Waals materials. The are disks patterned from isotopically pure hexagonal boron nitride (isotopes 10B and 11B) {\alpha}-molybdenum trioxide. experimentally achieved factors of nearly 400, highest ever observed nano-resonators at these wavelengths. excited modes deeply subwavelength, resonators 10 30 times smaller than exciting wavelength. These results very promising for...
Carbonaceous aerosols consist of a bulky but highly variable mass atmospheric aerosols, mostly comprised Organic Carbon (OC) and Elemental (EC). OC is emitted directly into the atmosphere or formed secondarily from photo-oxidation process that condensed semi- non-volatile compounds polymerizes organic species in atmosphere. EC mainly originate incomplete combustion biomass fossil fuels, have an instantaneous consequence on radiative forcing effect regional climate. This study was carried out...
We investigated infrared phonon polariton on thin hexagonal boron nitride flakes gold. successfully imaged ultraslow guided modes in both restrahlen bands, using photo-induced force microscopy and scattering type near field scanning optical microscopy.
We demonstrate single-layer metasurfaces with controllable multi-wavelength functions. A multiwavelength achromatic metalens for red, yellow, green and blue light, generating focused beams different orbital angular momentum states are designed fabricated.