139 research outputs found
Absorption and eigenmode calculation for one-dimensional periodic metallic structures using the hydrodynamic approximation
We develop a modal method that solves Maxwell's equations in the presence of
the linearized hydrodynamic correction. Using this approach, it is now possible
to calculate the full diffraction for structures with period of the order of
the plasma wavelength, including not only the transverse but also the
longitudinal modes appearing above the plasma frequency. As an example for
using this method we solve the diffraction of a plane wave near the plasma
frequency from a bi-metallic layer, modeled as a continuous variation of the
plasma frequency. We observe absorption oscillations around the plasma
frequency. The lower frequency absorption peaks and dips correspond to lowest
longitudinal modes concentrated in the lower plasma frequency region. As the
frequency is increased, higher order longitudinal modes are excited and extent
to the region of higher plasma frequency. Moreover, examination of the
propagation constants of these modes reveals that the absorption peaks and dips
are directly related to the direction of phase propagation of the longitudinal
modes. Furthermore, we formulate a variant of the Plane Wave Expansion method,
and used it to calculate the dispersion diagram of such longitudinal modes in a
periodically modulated plasma frequency layer
A microfluidic 2Ă—2 optical switch
A 2Ă—2 microfluidic-based optical switch is proposed and demonstrated. The switch is made of an optically clear silicon elastomer, Polydimethylsiloxane (PDMS), using soft lithography. It has insertion loss smaller than 1 dB and extinction ratio on the order of 20 dB. The device is switching between transmission (bypass) and reflection (exchange) modes within less than 20 m
Holographic Resonant Laser Printing of metasurfaces using plasmonic template
Laser printing with a spatial light modulator (SLM) has several advantages
over conventional raster-writing and dot-matrix display (DMD) writing: multiple
pixel exposure, high power endurance and existing software for computer
generated holograms (CGH). We present a technique for the design and
manufacturing of plasmonic metasurfaces based on ultrafast laser printing with
an SLM. As a proof of principle, we have used this technique to laser print a
plasmonic metalens as well as high resolution plasmonic color decorations. The
high throughput holographic resonant laser printing (HRLP) approach enables
on-demand mass-production of customized metasurfaces.Comment: Supplementary information is available upon request to author
Inversionless gain in a lossy medium
We study gain without inversion due to coherence effects in a
Doppler-broadened degenerate three-level system of a rubidium-hydrogen mixture
in a miniaturized micron scale custom vapor cell. The cell miniaturization
gives rise to collisions of atoms with the walls of the cell. This, combined
with the high collision rate with the hydrogen buffer gas allows us to observe
gain in the absorption spectra. Furthermore, we analyze the role of cell
miniaturization in the evolution of the gain profile. In addition to
fundamental interest, the observation of gain without inversion in our
miniaturized cells paves the way for applications such as miniaturized lasers
without inversion.Comment: 15 pages, 8 figures, 1 tabl
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