7 research outputs found
Superpixel-based spatial amplitude and phase modulation using a digital micromirror device
We present a superpixel method for full spatial phase and amplitude control
of a light beam using a digital micromirror device (DMD) combined with a
spatial filter. We combine square regions of nearby micromirrors into
superpixels by low pass filtering in a Fourier plane of the DMD. At each
superpixel we are able to independently modulate the phase and the amplitude of
light, while retaining a high resolution and the very high speed of a DMD. The
method achieves a measured fidelity for a target field with fully
independent phase and amplitude at a resolution of pixels per
diffraction limited spot. For the LG orbital angular momentum mode the
calculated fidelity is , using DMD pixels. The
superpixel method reduces the errors when compared to the state of the art Lee
holography method for these test fields by and , with a comparable
light efficiency of around . Our control software is publicly available.Comment: 9 pages, 6 figure
Pathlengths of open channels in multiple scattering media
We report optical measurements of the spectral width of open transmission
channels in a three-dimensional diffusive medium. The light transmission
through a sample is enhanced by efficiently coupling to open transmission
channels using repeated digital optical phase conjugation. The spectral
properties are investigated by enhancing the transmission, fixing the incident
wavefront and scanning the wavelength of the laser. We measure the transmitted
field to extract the field correlation function and the enhancement of the
total transmission. We find that optimizing the total transmission leads to a
significant increase in the frequency width of the field correlation function.
Additionally we find that the enhanced transmission persists over an even
larger frequency bandwidth. This result shows open channels in the diffusive
regime are spectrally much wider than previous measurements in the localized
regime suggest
Introduction to lattice gauge theories
SIGLEAvailable from CEN Saclay, Service de Documentation, 91191 - Gif-sur-Yvette Cedex (France) / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc
Secure communication with coded wavefronts
Communication between a sender and receiver can be made secure by encrypting the message using public or private shared keys. Quantum key distribution utilizes the unclonability of a quantum state to securely generate a key between the two parties [1]. However, without some way of authentication of either the sender or the receiver, a man-in-the-middle attack with an eavesdropper mimicking the receiver can break the security of the protocol
Supplement 1: Quantum-secure authentication of a physical unclonable key
Originally published in Optica on 20 December 2014 (optica-1-6-421