5,127 research outputs found
Multiplication and division of the orbital angular momentum of light with diffractive transformation optics
We present a method to efficiently multiply or divide the orbital angular
momentum (OAM) of light beams using a sequence of two optical elements. The
key-element is represented by an optical transformation mapping the azimuthal
phase gradient of the input OAM beam onto a circular sector. By combining
multiple circular-sector transformations into a single optical element, it is
possible to perform the multiplication of the value of the input OAM state by
splitting and mapping the phase onto complementary circular sectors.
Conversely, by combining multiple inverse transformations, the division of the
initial OAM value is achievable, by mapping distinct complementary circular
sectors of the input beam into an equal number of circular phase gradients. The
optical elements have been fabricated in the form of phase-only diffractive
optics with high-resolution electron-beam lithography. Optical tests confirm
the capability of the multiplier optics to perform integer multiplication of
the input OAM, while the designed dividers are demonstrated to correctly split
up the input beam into a complementary set of OAM beams. These elements can
find applications for the multiplicative generation of higher-order OAM modes,
optical information processing based on OAM-beams transmission, and optical
routing/switching in telecom.Comment: 28 pages, 10 figure
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Spectral imaging in preclinical research and clinical pathology.
Spectral imaging methods are attracting increased interest from researchers and practitioners in basic science, pre-clinical and clinical arenas. A combination of better labeling reagents and better optics creates opportunities to detect and measure multiple parameters at the molecular and cellular level. These tools can provide valuable insights into the basic mechanisms of life, and yield diagnostic and prognostic information for clinical applications. There are many multispectral technologies available, each with its own advantages and limitations. This chapter will present an overview of the rationale for spectral imaging, and discuss the hardware, software and sample labeling strategies that can optimize its usefulness in clinical settings
Metropolitan all-pass and inter-city quantum communication network
We have demonstrated a metropolitan all-pass quantum communication network in
field fiber for four nodes. Any two nodes of them can be connected in the
network to perform quantum key distribution (QKD). An optical switching module
is presented that enables arbitrary 2-connectivity among output ports.
Integrated QKD terminals are worked out, which can operate either as a
transmitter, a receiver, or even both at the same time. Furthermore, an
additional link in another city of 60 km fiber (up to 130 km) is seamless
integrated into this network based on a trusted relay architecture. On all the
links, we have implemented protocol of decoy state scheme. All of necessary
electrical hardware, synchronization, feedback control, network software,
execution of QKD protocols are made by tailored designing, which allow a
completely automatical and stable running. Our system has been put into
operation in Hefei in August 2009, and publicly demonstrated during an
evaluation conference on quantum network organized by the Chinese Academy of
Sciences on August 29, 2009. Real-time voice telephone with one-time pad
encoding between any two of the five nodes (four all-pass nodes plus one
additional node through relay) is successfully established in the network
within 60km.Comment: 9 pages, 2 figures, 2 table
Self-healing high-dimensional quantum key distribution using hybrid spin-orbit Bessel states
Using spatial modes for quantum key distribution (QKD) has become highly
topical due to their infinite dimensionality, promising high information
capacity per photon. However, spatial distortions reduce the feasible secret
key rates and compromise the security of a quantum channel. In an extreme form
such a distortion might be a physical obstacle, impeding line-of-sight for
free-space channels. Here, by controlling the radial degree of freedom of a
photon's spatial mode, we are able to demonstrate hybrid high-dimensional QKD
through obstacles with self-reconstructing single photons. We construct
high-dimensional mutually unbiased bases using spin-orbit hybrid states that
are radially modulated with a non-diffracting Bessel-Gaussian (BG) profile, and
show secure transmission through partially obstructed quantum links. Using a
prepare-measure protocol we report higher quantum state self-reconstruction and
information retention for the non-diffracting BG modes as compared to
Laguerre-Gaussian modes, obtaining a quantum bit error rate (QBER) that is up
to 3 times lower. This work highlights the importance of controlling the radial
mode of single photons in quantum information processing and communication as
well as the advantages of QKD with hybrid states.Comment: Published version, 15 pages, 6 figures, 2 table
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