193 research outputs found
Vanadium dioxide as a natural disordered metamaterial: perfect thermal emission and large broadband negative differential thermal emittance
We experimentally demonstrate that a thin (~150 nm) film of vanadium dioxide
(VO2) deposited on sapphire has an anomalous thermal emittance profile when
heated, which arises due to the optical interaction between the film and the
substrate when the VO2 is at an intermediate state of its insulator-metal
transition (IMT). Within the IMT region, the VO2 film comprises nanoscale
islands of metal- and dielectric-phase, and can thus be viewed as a natural,
disordered metamaterial. This structure displays "perfect" blackbody-like
thermal emissivity over a narrow wavelength range (~40 cm-1), surpassing the
emissivity of our black soot reference. We observed large broadband negative
differential thermal emittance over a >10 {\deg}C range: upon heating, the
VO2/sapphire structure emitted less thermal radiation and appeared colder on an
infrared camera. We anticipate that emissivity engineering with thin film
geometries comprising VO2 will find applications in infrared camouflage,
thermal regulation, infrared tagging and labeling.Comment: 3 figure
Recommended from our members
Holographic Detection of the Orbital Angular Momentum of Light With Plasmonic Photodiodes
Metallic components such as plasmonic gratings and plasmonic lenses are routinely used to convert free-space beams into propagating surface plasmon polaritons and vice versa. This generation of couplers handles relatively simple light beams, such as plane waves or Gaussian beams. Here we present a powerful generalization of this strategy to more complex wavefronts, such as vortex beams that carry orbital angular momentum, also known as topological charge. This approach is based on the principle of holography: the coupler is designed as the interference pattern of the incident vortex beam and focused surface plasmon polaritons. We have integrated these holographic plasmonic interfaces into commercial silicon photodiodes, and demonstrated that such devices can selectively detect the orbital angular momentum of light. This holographic approach is very general and can be used to selectively couple free-space beams into any type of surface wave, such as focused surface plasmon polaritons and plasmonic Airy beams.Physic
All-optical delay line using semiconductor cavity solitons (vol 92, 011101, 2008)
Correction of Pedaci, F. and Barland, S. and Caboche, E. and Firth, W.J. and Oppo, G.L. and Tredicce, J.R. and Ackemann, T. and Scroggie, A.J. (2008) All-optical delay line using semiconductor cavity solitons. Applied Physics Letters, 92 (1). ISSN 0003-695
Microresonator defects as sources of drifting cavity solitons
Cavity solitons (CS) are localized structures appearing as single intensity peaks in the homogeneous background of the field emitted by a nonlinear (micro)resonator. In real devices, their position is strongly influenced by the presence of defects in the device structure. In this Letter we show that the interplay between these defects and a phase gradient in the driving field induces the spontaneous formation of a regular sequence of CSs moving in the gradient direction. Hence, defects behave as a device built-in CS source, where the CS generation rate can be set by controlling the system parameters
Aberration-free ultra-thin flat lenses and axicons at telecom wavelengths based on plasmonic metasurfaces
The concept of optical phase discontinuities is applied to the design and
demonstration of aberration-free planar lenses and axicons, comprising a phased
array of ultrathin subwavelength spaced optical antennas. The lenses and
axicons consist of radial distributions of V-shaped nanoantennas that generate
respectively spherical wavefronts and non-diffracting Bessel beams at telecom
wavelengths. Simulations are also presented to show that our aberration-free
designs are applicable to high numerical aperture lenses such as flat
microscope objectives
Enhancing the gain by quantum coherence in terahertz quantum cascade lasers
We propose and study GaAs/AlGaAs terahertz frequency quantum cascade lasers in which mid-infrared radiation is used as a coherent drive for enhancing the terahertz gain
Generation of Two-Dimensional Plasmonic Bottle Beams
By analogy to the three dimensional optical bottle beam, we introduce the plasmonic bottle beam: a two dimensional surface wave which features a lattice of plasmonic bottles, i.e. alternating regions of bright focii surrounded by low intensities. The two-dimensional bottle beam is created by the interference of a non-diffracting beam, a cosine-Gaussian beam, and a plane wave, thus giving rise to a non-diffracting complex intensity distribution. By controlling the propagation constant of the cosine-Gauss beam, the size and number of plasmonic bottles can be engineered. The two dimensional lattice of hot spots formed by this new plasmonic wave could have applications in plasmonic trapping.Engineering and Applied Science
- …