746 research outputs found
Terahertz radiation due to random grating coupled surface plasmon polaritons
We report on terahertz (THz) radiation under electrical pumping from a
degenerate semiconductor possessing an electron accumulation layer. In InN, the
random grating formed by topographical defects provides high-efficiency
coupling of surface plasmon polaritons supported by the accumulation layer to
the THz emission. The principal emission band occupies the 2-6 THz spectral
range. We establish a link between the shape of emission spectra and the
structural factor of the random grating and show that the change of slope of
power dependencies is characteristic for temperature-dependent plasmonic
mechanisms. The super-linear rise of a THz emission intensity on applied
electric power provides advantage of such materials in emission yield.Comment: 4 pages, 4 figure
Upconversion cooling of Er-doped low-phonon fluorescent solids
We report on a novel mechanism for laser cooling of fluorescent solids based
on infrared-to-visible upconversion often found in rare-earth-doped low-phonon
materials. This type of optical cooling presents some advantages with regards
to conventional anti-Stokes cooling. Among them, it allows to obtain cooling in
a broader range of frequencies around the barycenter of the infrared emitting
band.Comment: 4 pages, 1 figur
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