We present elastic neutron scattering results at high magnetic fields for Mg-doped CuGeO 3. For low magnesium concentrations, where a spin-Peierls phase is present, we find an enhancement of the long range antiferromagnetic order in the structural incommensurate phase induced by a high magnetic field. In the incommensurate phase, the Néel temperature increases with field leading to a gain in th...

A direct UV grating writing technique based on phase-controlled interferometry is proposed and demonstrated in a silica-on-silicon platform, with a wider wavelength detuning range than any previously reported UV writing technology. Electro-optic phase modulation of one beam in the interferometer is used to manipulate the fringe pattern and thus control the parameters of the Bragg gratings and w...

Wepresent a theoretical investigation of the dynamic density structure factor of a strongly interacting Fermi gas near the Feshbach resonance atfinite temperature, which can be exploited in two photon Bragg scattering experiments. This study is based on a fully gauge invariant linear response theory, which is consistent with a diagrammatic approach for the equilibrium state taking into account ...

Features of forward diffracted Parametric X-Radiation (PXR) were investigated at experiments with the 855 MeV electron beam of the Mainz Microtron MAMI employing a 410 μm thick tungsten single crystal. Virtual photons from the electron field are diffracted by the (101̄) plane at a Bragg angle of 3.977. Forward emitted radiation was analyzed at an energy of 40 keV with the (111) lattice planes of...

Optical gas detection in microsystems is limited by the short micron scale optical path length available. Recently, the concept of slow-light enhanced absorption has been proposed as a route to compensate for the short path length in miniaturized absorption cells. We extend the previous perturbation theory to the case of a Bragg stack infiltrated by a spectrally strongly dispersive gas with a n...

We report the study of laser-induced coherent lattice motions using femtosecond electron diffraction. The oscillations of Bragg peak positions associated with a damped lattice vibration along the surface normal were directly observed in real time and with sub-milli-angstrom spatial resolution. In addition, by using a pair of optical excitation pulses and varying their time delay and relative pu...

The melting transition of DNA, whereby the strands of the double-helix structure completely separate at a certain temperature, has been characterized using neutron scattering. A Bragg peak from B-form fiber DNA has been measured as a function of temperature, and its widths and integrated intensities have been interpreted using the Peyrard-Bishop-Dauxois model with only one free parameter. The e...

We present simulation and experimental results of fiber Bragg grating responses to transverse stress in microstructure fibers. The grating wavelength shifts and peak splits are studied as a function of external load and fiber orientation. Both simulation and measurement results indicate that the sensitivity of grating sensors to the transverse stress can be enhanced by a factor of eight in a tw...

Charged-particle beams consisting of protons or helium ions are a type of particulate radiation therapy. They contrast with conventional electromagnetic (i.e., photon) radiation therapy due to several unique properties including minimal scatter as particulate beams pass through tissue, and deposition of ionizing energy at precise depths (i.e., the Bragg peak). Thus, radiation exposure of surrou...

We report, for the first time to our knowledge, the experimental observation of quasi-cw nonlinear switching and multiple gap-soliton formation within the bandgap of a fiber Bragg grating. As many as five gap solitons with 100-500-ps durations were generated from a 2-ns pulse at a launched peak intensity of approximately 27 GW/cm(2). A corresponding increase in the grating transmission from 3% ...