8,643 research outputs found
Absence of Localization in Certain Field Effect Transistors
We review some experimental and theoretical results on the metal-to-insulator
transition (MIT) observed at zero magnetic field (B=0) in several
two-dimensional electron systems (2DES). Scaling of the conductance and
magnetic field dependence of the conductance provide convincing evidence that
the MIT is driven by Coulomb interactions among the carriers and is
dramatically sensitive to spin polarization of the carriers.Comment: 8 pages, LaTeX, figure label change
Return to work after stroke in Hong Kong. Part 2: a psychosocial perspective
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Return to work after stroke in Hong Kong. Part 1: a biological perspective
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Integrated production and distribution scheduling problems related with fixed delivery departure dates and number of late orders
Prediction of recovery of swallowing disorder in stroke patients after rehabilitation
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Nonlinear lightwave circuits in chalcogenide glasses fabricated by ultrafast laser
This Letter reports a nonlinear directional waveguide coupler written by ultrafast laser in gallium lanthanum sulfide chalcogenide glass. The nonlinear waveguide device is tested with laser pulses input in two orthogonal polarizations, and all optical switching at 1040 nm between the two coupled waveguides is observed at a peak fluence of 16 GW?cm2. The spectra and autocorrelation measurement from the waveguide outputs show dominant nonlinear effects and negligible dispersion for light propagation in both channels. © 2014 Optical Society of America
Ultrafast laser fabrication of Bragg waveguides in chalcogenide glass
Bragg waveguides are fundamental components in photonic integrated circuits and are particularly interesting for mid-IR applications in high index, highly nonlinear materials. In this work, we present Bragg waveguides fabricated in bulk chalcogenide glass using an ultrafast laser. Waveguides with near circularly symmetric cross sections and low propagation loss are obtained through spatial and temporal beam shaping. Using a single-pass technique, the waveguide and Bragg structure are formed at the same time. First through sixth order gratings with strengths of up to 25 dB are realized, and performance is evaluated based on the modulation duty cycle of the writing beam. © 2014 Optical Society of America
Nonlinear optical localization in embedded chalcogenide waveguide arrays
We report the nonlinear optical localization in an embedded waveguide array fabricated in chalcogenide glass. The array, which consists of seven waveguides with circularly symmetric cross sections, is realized by ultrafast laser writing. Light propagation in the chalcogenide waveguide array is studied with near infrared laser pulses centered at 1040 nm. The peak intensity required for nonlinear localization for the 1-cm long waveguide array was 35.1 GW/cm 2, using 10-nJ pulses with 300-fs pulse width, which is 70 times lower than that reported in fused silica waveguide arrays and with over 7 times shorter interaction distance. Results reported in this paper demonstrated that ultrafast laser writing is a viable tool to produce 3D all-optical switching waveguide circuits in chalcogenide glass. © 2014 Author(s)
Haemorrhagic stroke vs ischaemic stroke: length of stay and functional outcome measures in stroke survivors
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