The concept of optical phase discontinuities is applied to the design and demonstration aberration-free planar lenses axicons, comprising a phased array ultrathin subwavelength spaced antennas. axicons consist radial distributions V-shaped nanoantennas that generate respectively spherical wavefronts non-diffracting Bessel beams at telecom wavelengths. Simulations are also presented show our designs applicable high numerical aperture such as flat microscope objectives.

We show that perfect absorption can be achieved in a system comprising single lossy dielectric layer of thickness much smaller than the incident wavelength on an opaque substrate by utilizing nontrivial phase shifts at interfaces between media. This design is implemented with ultra-thin (∼λ/65) vanadium dioxide (VO2) sapphire, temperature tuned vicinity VO2 insulator-to-metal transition, leading to 99.75% λ = 11.6 μm. The structural simplicity and large tuning range (from ∼80% 0.25%...

A flat optical device that generates vortices with a variety of topological charges is demonstrated. This spatially modulates light beams over distance much smaller than the wavelength in direction propagation by means an array V-shaped plasmonic antennas sub-wavelength separation. Optical are shown to develop after from array, feature has major potential implications for integrated optics.

Conventional optical components rely on the propagation effect to control phase and polarization of light beams. One can instead exploit abrupt changes associated with scattered from resonators propagation. In this paper, we discuss responses anisotropic plasmonic antennas a new class planar ("metasurfaces") based arrays these antennas. To demonstrate versatility metasurfaces, show design experimental realization number flat components: 1) metasurfaces constant interfacial gradient that...

We demonstrate that the resonances of infrared plasmonic antennas can be tuned or switched on/off by taking advantage thermally driven insulator-to-metal phase transition in vanadium dioxide (VO2). Y-shaped were fabricated on a 180 nm film VO2 deposited sapphire substrate, and their shown to depend temperature proximity its transition, good agreement with full-wave simulations. achieved tunability resonance wavelength approximately 10% (>1 μm at λ∼10 μm).

Thermal radiation from conventional emitters, such as the warm glow of a light bulb, increases with temperature: hotter more it glows. emitters that buck this trend could lead to many unconventional thermal devices. Researchers have engineered (meta)material by exploiting unique structural and electronic phase changes vanadium oxide at around 70${}^{\ensuremath{\circ}}$C.

Enhancing nonlinear processes at the nanoscale is a crucial step toward development of nanophotonics and new spectroscopy techniques. Here we demonstrate novel plasmonic structure, called nanocavity grating, which shown to dramatically enhance surface optical processes. It consists resonant cavities that are periodically arranged combine local grating resonances. The four-wave mixing signal generated in our gold enhanced by factor up ≈2000, 2 orders magnitude higher than previously reported.

The manipulation of light by conventional optical components such as lenses, prisms, and waveplates involves engineering the wavefront it propagates through an optically thick medium. A unique class flat with high functionality can be designed introducing abrupt phase shifts into path, utilizing resonant response arrays scatterers deeply subwavelength thickness. As application this concept, we report a theoretical experimental study birefringent two-dimensional (V- Y-shaped) antennas which...

Significance Renewable energy can be generated whenever heat flows from a hotter to colder body. One such flow is the warm surface of Earth cold outer space, via infrared thermal radiation. An emissive harvester (EEH) device that generate emitting radiation into clear sky. We calculate how much power thermodynamically available, using location in Oklahoma as case study. discuss two possible ways make device: A EEH (analogous solar generation) and an optoelectronic photovoltaic generation)....

We present a simplified numerical method to solve for the current distribution in V-shaped antenna excited by an electric field with arbitrary polarization. The scattered far-field amplitude, phase, and polarization of antennas are extracted. calculation technique presented here is efficient probing large design parameter space such antennas, which have been proposed as basic building blocks ultrathin plasmonic metasurfaces. Our based on integral equation moments validated comparison results...

We describe the properties of guided modes in metallic parallel plate structures with subwavelength corrugation on surfaces both conductors, which we refer to as spoof-insulator-spoof (SIS) waveguides, close analogy metal-insulator-metal (MIM) waveguides plasmonics. A dispersion relation for SIS is derived, and are shown arise from coupling conventional waveguide localized grooves structure. have numerous design parameters can be engineered guide very low group velocities adiabatically...

Recently a new class of optical interference coatings was introduced which comprises ultra-thin, highly absorbing dielectric layers on metal substrates. We show that these lossy can be augmented by an additional transparent subwavelength layer. fabricated sample comprising gold substrate, ultra-thin film germanium with thickness gradient, and several alumina films. The experimental reflectivity spectra showed the layer increases color range obtained, in agreement calculations. More...

Here we report on the broadband detection of nitrous oxide (N2O) and methane (CH4) mixtures in dry nitrogen by using a quartz-enhanced photoacoustic (QEPAS) sensor exploiting an array 32 distributed-feedback quantum cascade lasers, within spectral emission range 1190-1340 cm-1 as excitation source. Methane down to minimum limit 200 ppb at 10 s lock-in integration time was achieved. The demonstrated linear response 200-1000 ppm. Three different N2O CH4 atmospheric pressure have been analyzed....

We demonstrate instrumentation and methods to enable fluorescence-detected photothermal infrared (F-PTIR) microscopy then the utility of F-PTIR characterize composition within phase-separated domains model amorphous solid dispersions (ASDs) induced by water sorption. In F-PTIR, temperature-dependent changes in fluorescence quantum efficiency are shown sensitively report on highly localized absorption mid-infrared radiation. The spatial resolution with which spectroscopy can be performed is...

Using quantum cascade lasers with a two-dimensional metallic aperture-grating structure defined on the facet authors demonstrate collimated laser beam small divergence angle perpendicular and parallel to waveguide layers (2.7° 3.7°, respectively). These values represent reduction by factor of ∼30 ∼10, respectively, compared those original 8.06-μm- wavelength without plasmonic collimation. The devices preserve good room temperature performance output power as high 53% that unpatterned lasers.

We demonstrated in simulations and experiments that by defining a properly designed two-dimensional metallic aperture-grating structure on the facet of quantum cascade lasers, small beam divergence angle can be achieved directions both perpendicular parallel to laser waveguide layers (denoted as theta parallel, respectively). Beam angles perpendicular=2.7 degrees parallel=3.7 have been demonstrated. This is reduction factor approximately 30 10, respectively, compared those original lasers...

Although much thinner than conventional optical interference coatings, nanometer-thick films made of optically absorbing materials can display strong effects. This new class coatings shows promise for coloring and labeling, filters, tunable absorbers emitters, energy harvesting.

We propose a robust and reliable method of active mode locking mid-infrared quantum cascade lasers develop its theoretical description. Its key element is the use an external ring cavity, which circumvents fundamental issues undermining stability in lasers. show that can give rise to generation picosecond pulses phase-locked frequency combs containing thousands cavity modes.

We present a gas sensing system based on quartz-enhanced photoacoustic spectroscopy (QEPAS) employing monolithic distributed-feedback quantum cascade laser (QCL) array operated in pulsed mode as light source. The consists of 32 lasers emitting spectral range from 1190 cm−1 to 1340 cm−1. optoacoustic detection module was composed custom quartz tuning fork with prong spacing 1 mm, coupled two micro-resonator tubes enhance the signal-to-noise ratio. QEPAS sensor validated by detecting...

We demonstrate a three-section, electrically pulsed quantum cascade laser which consists of Fabry-Pérot section placed between two sampled grating distributed Bragg reflectors. The device is current-tuned ten single modes spanning range 0.46 μm (63 cm(-1)), from 8.32 to 8.78 μm. peak optical output power exceeds 280 mW for nine the modes.

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> This paper reviews our recent work on laser beam shaping using plasmonics. We demonstrated that by integrating properly designed plasmonic structures onto the facet of semiconductor lasers, their divergence angle can be dramatically reduced more than one orders magnitude, down to a few degrees. A collimator consisting slit aperture and an adjacent 1-D grating collimate light in polarization...

We designed a new class of plasmonic gratings that generate multiple free-space beams in arbitrary directions from point source surface waves, using phenomenological model accurately predicts their far-field, amplitude, phase and polarization. fabricated such on the facets semiconductor lasers. The proposed here are generally relevant to interfacing nanoscale optical components beams. introduced can be used design general two-dimensional gratings.

We propose and demonstrate a novel photonic-plasmonic antenna capable of confining electromagnetic radiation at several mid-infrared wavelengths to single sub-wavelength spot. The structure relies on the coupling between localized surface plasmon resonance bow-tie nanoantenna with photonic modes surrounding multi-periodic particle arrays. Far-field measurements transmission through central presence Fano-like interference effects resulting from interaction nanoparticle near-field...