5,313 research outputs found
Diamond electro-optomechanical resonators integrated in nanophotonic circuits
Diamond integrated photonic devices are promising candidates for emerging
applications in nanophotonics and quantum optics. Here we demonstrate active
modulation of diamond nanophotonic circuits by exploiting mechanical degrees of
freedom in free-standing diamond electro-optomechanical resonators. We obtain
high quality factors up to 9600, allowing us to read out the driven
nanomechanical response with integrated optical interferometers with high
sensitivity. We are able to excite higher order mechanical modes up to 115 MHz
and observe the nanomechanical response also under ambient conditions.Comment: 15 pages, 4 figure
Evolution of microstructure and optical properties of TiO2/Au nanocomposite
TiO2/Au nanocomposite has been synthesized by mixing Au with milled TiO2 nanopowder through wet chemical route. The effect of Au on the microstructural and optical properties of TiO2 nanopowder has been studied by XRD, FESEM, UV Visible, PL and FTIR techniques. Our study indicates that Au causes the decrease of crystallite size of TiO2 by accumulating on the circumference of these nanoparticles. TiO2/Au nanocomposite exhibits strong spectral response in the visible range due to the surface plasmon effect. Band gap of TiO2 nanopowder reduces from 3.4 eV to 3.1 eV while making composite with Au. The PL spectra showed that emission peak intensity of TiO2 nanopowder decreases in the presence of Au. The reductions in band gap and electron-hole recombination in TiO2/Au nanocomposite suggest that TiO2/Au could be a good candidate for photocatalysis
New limit for the half-life of double beta decay of Zr to the first excited state of Mo
Neutrinoless Double Beta Decay is a phenomenon of fundamental interest in
particle physics. The decay rates of double beta decay transitions to the
excited states can provide input for Nuclear Transition Matrix Element
calculations for the relevant two neutrino double beta decay process. It can be
useful as supplementary information for the calculation of Nuclear Transition
Matrix Element for the neutrinoless double beta decay process. In the present
work, double beta decay of Zr to the excited state of
Mo at 871.1 keV is studied using a low background 230 cm HPGe
detector. No evidence of this decay was found with a 232 g.y exposure of
natural Zirconium. The lower half-life limit obtained for the double beta decay
of to the excited state of is y at 90% C.L., an improvement by a factor of
4 over the existing experimental limit at 90\% C.L. The sensitivity is
estimated to be y at 90% C.L. using
the Feldman-Cousins method.Comment: 11 pages, 7 figures, Accepted in Eur. Phys. J.
High-Q optomechanical circuits made from polished nanocrystalline diamond thin films
We demonstrate integrated optomechanical circuits with high mechanical
quality factors prepared from nanocrystalline diamond thin films. Using
chemomechanical polishing, the RMS surface roughness of as grown
polycrystalline diamond films is reduced below 3nm to allow for the fabrication
of high-quality nanophotonic circuits. By integrating free-standing
nanomechanical resonators into integrated optical devices, efficient read-out
of the thermomechanical motion of diamond resonators is achieved with on-chip
Mach-Zehnder interferometers. Mechanical quality factors up to 28,800 are
measured for four-fold clamped optomechanical resonators coupled to the
evanescent near-field of nanophotonic waveguides. Our platform holds promise
for large-scale integration of optomechanical circuits for on-chip metrology
and sensing applications
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