In this paper, we describe a detailed performance comparison of alternative single-pixel, single-mode LIDAR
architectures including (i) linear-mode APD-based direct-detection, (ii) optically-preamplified PIN receiver, (iii) PINbased
coherent-detection, and (iv) Geiger-mode single-photon-APD counting. Such a comparison is useful when
considering next-generation LIDAR on a chip, which would allow one to leverage extensive waveguide-based structures
and processing elements developed for telecom and apply them to small form-factor sensing applications. Models of
four LIDAR transmit and receive systems are described in detail, which include not only the dominant sources of
receiver noise commonly assumed in each of the four detection limits, but also additional noise terms present in realistic
implementations. These receiver models are validated through the analysis of detection statistics collected from an
experimental LIDAR testbed. The receiver is reconfigurable into four modes of operation, while transmit waveforms
and channel characteristics are held constant. The use of a diffuse hard target highlights the importance of including
speckle noise terms in the overall system analysis. All measurements are done at 1550 nm, which offers multiple system
advantages including less stringent eye safety requirements and compatibility with available telecom components,
optical amplification, and photonic integration. Ultimately, the experimentally-validated detection statistics can be used
as part of an end-to-end system model for projecting rate, range, and resolution performance limits and tradeoffs of
alternative integrated LIDAR architectures.
We describe how hyperentanglement may be used to give orders of magnitude throughput improvement over singly entangled photon pairs, for some applications. Next we demonstrate the first measurement of hyperentangled photon pairs, both of which are at telecom wavelengths, via simultaneous polarization tomography and time-bin interference measurements. Without cryogenic cooling of the nonlinear element, we measure polarization entanglement with tangle of 0.4 ± 0.2 and time bin entanglement with visibility of 83% ± 6%, both exceeding classical thresholds by approximately two standard deviations.
In this paper, we review recent developments in coherent, spectral phase encoded optical code-division multiplexed
(OCDM) systems employing integrated micro-ring resonator coding technologies and consider its application to data
confidentiality in optical networks. In addition, we discuss how such systems can be designed to be compatible with
conventional dense wavelength-division multiplexing (DWDM) networking, and review our experimental progress in
advanced modulation formats for improved spectral efficiency (up to 0.87 b/s/Hz) as well as the capability for long
transmission distances (up to 400 km).
Quantum communications is an emerging field with many promising applications. Its usefulness and range of
applicability in optical fiber will depend strongly on the extent to which quantum channels can be reliably transported
over transparent reconfigurable optical networks, rather than being limited to dedicated point-to-point links. This
presents a number of challenges, particularly when single-photon quantum and much higher power classical optical
signals are combined onto a single physical infrastructure to take advantage of telecom networks built to carry
conventional traffic. In this paper, we report on experimental demonstrations of successful quantum key distribution
(QKD) in this complex environment, and on measurements of physical-layer impairments, including Raman scattering
from classical optical channels, which can limit QKD performance. We then extend the analysis using analytical models
incorporating impairments, to investigate QKD performance while multiplexed with conventional data channels at other
wavelengths. Finally, we discuss the implications of these results for evaluating the most promising domains of use for
QKD in real-world optical networks.
Quantum communications is fast becoming an important component of many applications in quantum information
science. Sharing quantum information over a distance among geographically separated nodes using photonic qubits
requires a reconfigurable transparent networking infrastructure that can support quantum information services. Using
quantum key distribution (QKD) as an example of a quantum communications service, we investigate the ability of fiber
networks to support both conventional optical traffic and single-photon quantum communications signals on a shared
infrastructure. The effect of Raman scattering from conventional channels on the quantum bit error rate (QBER) of a
QKD system is analyzed. Additionally, the potential impact and mitigation strategies of other transmission impairments
such as four-wave mixing, cross-phase modulation, and noise from mid-span optical amplifiers are discussed. We also
review recent trends toward the development of automated and integrated QKD systems which are important steps
toward reliable and manufacturable quantum communications systems.
Quantum key distribution (QKD) is an emerging technology for secure distribution of keys between users linked by free-space or fiber optic transmission facilities. QKD has usually been designed for and operated over dedicated point-to-point links. However, the commercial world has been developing increasingly sophisticated fiber networks, with basic networking functions such as routing and multiplexing performed in the optical domain. One of the most important practical questions for the future of QKD is to what extent it can benefit from these trends, either to expand the capabilities of dedicated quantum networks, or to avoid the need for dedicated networks by combining quantum and conventional optical signals onto a single infrastructure.
In this paper, we report on systematic investigations of these issues using a 1310-nm weak-coherent, phase-encoded B92 prototype QKD system developed by Los Alamos that includes the implementation of error correction, privacy amplification, and authentication. We have demonstrated reconfigurability of QKD networks via optical switching and successful QKD operation in the presence of amplified DWDM signals over 10 km of fiber. We have identified anti-Stokes Raman scattering of the DWDM signals in the fiber as a dominant transmission impairment for QKD, and developed filtering architectures to extend transmission distances to at least 25 km. We have also measured noise backgrounds and polarization variations in network fibers to understand applicability to real-world networks. We will discuss the implications of our results for the choice of QKD wavelengths, wavelength-spacing between QKD and conventional channels, and QKD network architectures.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.