534 research outputs found
O-Band Subwavelength Grating Filters in a Monolithic Photonics Technology
The data communications industry has begun transitioning from electrical to
optical interconnects in datacenters in order to overcome performance
bottlenecks and meet consumer needs. To mitigate the costs associated with this
change and achieve performance for 5G and beyond, it is crucial to explore
advanced photonic devices that can enable high-bandwidth interconnects via
wavelength-division multiplexing (WDM) in photonic integrated circuits.
Subwavelength grating (SWG) filters have shown great promise for WDM
applications. However, the small feature sizes necessary to implement these
structures have prohibited them from penetrating into industrial applications.
To explore the manufacturability and performance of SWG filters in an
industrial setting, we fabricate and characterize O-band subwavelength grating
filters using the monolithic photonics technology at GLOBALFOUNDRIES (GF). We
demonstrate a low drop channel loss of -1.2 dB with a flat-top response, a high
extinction ratio of -30 dB, a 3 dB channel width of 5 nm and single-source
thermal tunability without shape distortion. This filter structure was designed
using elements from the product design kit provided by GF and functions in a
compact footprint of 0.002 mm2 with a minimum feature size of 150 nm.Comment: 4 pages, 3 figure
The Polarized 3-He Target
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Polarization observables in p-d scattering below 30 MeV
Differential and total breakup cross sections as well as vector and tensor
analyzing powers for p-d scattering are studied for energies above the deuteron
breakup threshold up to E(lab)=28 MeV. The p-d scattering wave function is
expanded in terms of the correlated hyperspherical harmonic basis and the
elastic S-matrix is obtained using the Kohn variational principle in its
complex form. The effects of the Coulomb interaction, which are expected to be
important in this energy range, have been rigorously taken into account. The
Argonne AV18 interaction and the Urbana URIX three-nucleon potential have been
used to perform a comparison to the available experimental data.Comment: 31 pages, 8 figure
Status of an Investigation of the 3-He Wave Function by Quasi-Free Scattering
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Measurement of Angular Distributions and R= sigma_L/sigma_T in Diffractive Electroproduction of rho^0 Mesons
Production and decay angular distributions were extracted from measurements
of exclusive electroproduction of the rho^0(770) meson over a range in the
virtual photon negative four-momentum squared 0.5< Q^2 <4 GeV^2 and the
photon-nucleon invariant mass range 3.8< W <6.5 GeV. The experiment was
performed with the HERMES spectrometer, using a longitudinally polarized
positron beam and a ^3He gas target internal to the HERA e^{+-} storage ring.
The event sample combines rho^0 mesons produced incoherently off individual
nucleons and coherently off the nucleus as a whole. The distributions in one
production angle and two angles describing the rho^0 -> pi+ pi- decay yielded
measurements of eight elements of the spin-density matrix, including one that
had not been measured before. The results are consistent with the dominance of
helicity-conserving amplitudes and natural parity exchange. The improved
precision achieved at 47 GeV,
reveals evidence for an energy dependence in the ratio R of the longitudinal to
transverse cross sections at constant Q^2.Comment: 15 pages, 15 embedded figures, LaTeX for SVJour(epj) document class
Revision: Fig. 15 corrected, recent data added to Figs. 10,12,14,15; minor
changes to tex
Status of an Investigation of the 3-He Wave Function by Quasi-Free Scattering
This research was sponsored by the National Science Fooundation Grant NSF PHY-931478
Status of an Investigation of the 3-He Wave Function by Quasi-Free Scattering
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Beam-Induced Nuclear Depolarisation in a Gaseous Polarised Hydrogen Target
Spin-polarised atomic hydrogen is used as a gaseous polarised proton target
in high energy and nuclear physics experiments operating with internal beams in
storage rings. When such beams are intense and bunched, this type of target can
be depolarised by a resonant interaction with the transient magnetic field
generated by the beam bunches. This effect has been studied with the HERA
positron beam in the HERMES experiment at DESY. Resonances have been observed
and a simple analytic model has been used to explain their shape and position.
Operating conditions for the experiment have been found where there is no
significant target depolarisation due to this effect.Comment: REVTEX, 6 pages, 5 figure
Measurement of the Neutron Spin Structure Function with a Polarized ^3He Target
Results are reported from the HERMES experiment at HERA on a measurement of
the neutron spin structure function in deep inelastic scattering
using 27.5 GeV longitudinally polarized positrons incident on a polarized
He internal gas target. The data cover the kinematic range
and . The integral evaluated at a fixed of is . Assuming Regge behavior at low , the first
moment is .Comment: 4 pages TEX, text available at
http://www.krl.caltech.edu/preprints/OAP.htm
Determination of the Deep Inelastic Contribution to the Generalised Gerasimov-Drell-Hearn Integral for the Proton and Neutron
The virtual photon absorption cross section differences [sigma_1/2-sigma_3/2]
for the proton and neutron have been determined from measurements of polarised
cross section asymmetries in deep inelastic scattering of 27.5 GeV
longitudinally polarised positrons from polarised 1H and 3He internal gas
targets. The data were collected in the region above the nucleon resonances in
the kinematic range nu < 23.5 GeV and 0.8 GeV**2 < Q**2 < 12 GeV**2. For the
proton the contribution to the generalised Gerasimov-Drell-Hearn integral was
found to be substantial and must be included for an accurate determination of
the full integral. Furthermore the data are consistent with a QCD
next-to-leading order fit based on previous deep inelastic scattering data.
Therefore higher twist effects do not appear significant.Comment: 6 pages, 3 figures, 1 table, revte
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