RESUMO
We demonstrate free-space space-division-multiplexing (SDM) with 15 orbital angular momentum (OAM) states using a three-dimensional (3D) photonic integrated circuit (PIC). The hybrid device consists of a silica planar lightwave circuit (PLC) coupled to a 3D waveguide circuit to multiplex/demultiplex OAM states. The low excess loss hybrid device is used in individual and two simultaneous OAM states multiplexing and demultiplexing link experiments with a 20 Gb/s, 1.67 b/s/Hz quadrature phase shift keyed (QPSK) signal, which shows error-free performance for 379,960 tested bits for all OAM states.
RESUMO
Using micro-fabrication techniques, we have manufactured a single element kinoform lens in single-crystal silicon with an elliptical profile for 12.398 keV (1A) x-rays. By fabricating a lens that is optimized at fixed wavelengths, absorption in the lens material can be significantly reduced by removing 2_ phase-shifting regions. This permits short focal length devices to be fabricated with small radii of curvatures at the lens apex. This feature allows one to obtain a high demagnification of a finite synchrotron electron source size. The reduced absorption loss also enables optics with a larger aperture, and hence improved resolution for focusing and imaging applications. Our first trial of these lenses has resulted in a one micron line focus (fwhm) at the National Synchrotron Light Source X13B beamline.
