15,130 research outputs found
Ultrafast all-optical switching via coherent modulation of metamaterial absorption
We report on the demonstration of a femtosecond all-optical modulator
providing, without nonlinearity and therefore at arbitrarily low intensity,
ultrafast light-by-light control. The device engages the coherent interaction
of optical waves on a metamaterial nanostructure only 30 nm thick to
efficiently control absorption of near-infrared (750-1040 nm) femtosecond
pulses, providing switching contrast ratios approaching 3:1 with a modulation
bandwidth in excess of 2 THz. The functional paradigm illustrated here opens
the path to a family of novel meta-devices for ultra-fast optical data
processing in coherent networks.Comment: 5 pages, 4 figure
Electronic and photonic switching in the atm era
Broadband networks require high-capacity switches in order to properly manage large amounts of traffic fluxes. Electronic and photonic technologies are being used to achieve this objective both allowing different multiplexing and switching techniques. Focusing on the asynchronous transfer mode (ATM), the inherent different characteristics of electronics and photonics makes different architectures feasible. In this paper, different switching structures are described, several ATM switching architectures which have been recently implemented are presented and the implementation characteristics discussed. Three diverse points of view are given from the electronic research, the photonic research and the commercial switches. Although all the architectures where successfully tested, they should also follow different market requirements in order to be commercialised. The characteristics are presented and the architectures projected over them to evaluate their commercial capabilities.Peer ReviewedPostprint (published version
Highly Efficient Coupling of Nanolight Emitters to a Ultra-wide Tunable Nanofibre Cavity
Solid-state microcavities combining ultra-small mode volume, wide-range
resonance frequency tuning, as well as lossless coupling to a single mode fibre
are integral tools for nanophotonics and quantum networks. We developed an
integrated system providing all of these three indispensable properties. It
consists of a nanofibre Bragg cavity (NFBC) with the mode volume of under 1
micro cubic meter and repeatable tuning capability over more than 20 nm at
visible wavelengths. In order to demonstrate quantum light-matter interaction,
we establish coupling of quantum dots to our tunable NFBC and achieve an
emission enhancement by a factor of 2.7.Comment: 19 pages, 8 figures, including Supporting Information (5 pages, 4
figures), accepted for SCIENTIFC REPORT
Frequency Multiplexing for Quasi-Deterministic Heralded Single-Photon Sources
Single-photon sources based on optical parametric processes have been used
extensively for quantum information applications due to their flexibility,
room-temperature operation and potential for photonic integration. However, the
intrinsically probabilistic nature of these sources is a major limitation for
realizing large-scale quantum networks. Active feedforward switching of photons
from multiple probabilistic sources is a promising approach that can be used to
build a deterministic source. However, previous implementations of this
approach that utilize spatial and/or temporal multiplexing suffer from rapidly
increasing switching losses when scaled to a large number of modes. Here, we
break this limitation via frequency multiplexing in which the switching losses
remain fixed irrespective of the number of modes. We use the third-order
nonlinear process of Bragg scattering four-wave mixing as an efficient
ultra-low noise frequency switch and demonstrate multiplexing of three
frequency modes. We achieve a record generation rate of
multiplexed photons per second with an ultra-low = 0.07, indicating
high single-photon purity. Our scalable, all-fiber multiplexing system has a
total loss of just 1.3 dB independent of the number of multiplexed modes, such
that the 4.8 dB enhancement from multiplexing three frequency modes markedly
overcomes switching loss. Our approach offers a highly promising path to
creating a deterministic photon source that can be integrated on a chip-based
platform.Comment: 28 pages, 9 figures. Comments welcom
Efficient fiber-optical interface for nanophotonic devices
We demonstrate a method for efficient coupling of guided light from a single
mode optical fiber to nanophotonic devices. Our approach makes use of
single-sided conical tapered optical fibers that are evanescently coupled over
the last ~10 um to a nanophotonic waveguide. By means of adiabatic mode
transfer using a properly chosen taper, single-mode fiber-waveguide coupling
efficiencies as high as 97(1)% are achieved. Efficient coupling is obtained for
a wide range of device geometries which are either singly-clamped on a chip or
attached to the fiber, demonstrating a promising approach for integrated
nanophotonic circuits, quantum optical and nanoscale sensing applications.Comment: 7 pages, 4 figures, includes supplementary informatio
Optimizing optical Bragg scattering for single-photon frequency conversion
We develop a systematic theory for optimising single-photon frequency
conversion using optical Bragg scattering. The efficiency and phase-matching
conditions for the desired Bragg scattering conversion as well as spurious
scattering and modulation instability are identified. We find that third-order
dispersion can suppress unwanted processes, while dispersion above the fourth
order limits the maximum conversion efficiency. We apply the optimisation
conditions to frequency conversion in highly nonlinear fiber, silicon nitride
waveguides and silicon nanowires. Efficient conversion is confirmed using full
numerical simulations. These design rules will assist the development of
efficient quantum frequency conversion between multicolour single photon
sources for integration in complex quantum networks.Comment: 9 pages, 14 figure
Enhancing quantum transport in a photonic network using controllable decoherence
Transport phenomena on a quantum scale appear in a variety of systems,
ranging from photosynthetic complexes to engineered quantum devices. It has
been predicted that the efficiency of quantum transport can be enhanced through
dynamic interaction between the system and a noisy environment. We report the
first experimental demonstration of such environment-assisted quantum
transport, using an engineered network of laser-written waveguides, with
relative energies and inter-waveguide couplings tailored to yield the desired
Hamiltonian. Controllable decoherence is simulated via broadening the bandwidth
of the input illumination, yielding a significant increase in transport
efficiency relative to the narrowband case. We show integrated optics to be
suitable for simulating specific target Hamiltonians as well as open quantum
systems with controllable loss and decoherence.Comment: 6 pages, 3 figure
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