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At least 109 records · Page 6

Testing of A Photon-Counting Optical Ground Receiver With Emulated Space-to-Ground Link Effects

The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) developed and previously characterized a photon-counting optical ground receiver system. The receiver is compliant with the Consultative Committee for Space Data Systems (CCSDS) Optical Communications Coding and Synchronization High Photon Efficiency (HPE) Standard. The standard will be used on the Optical Artemis-2 Orion (O2O) communications demonstration and the Deep Space Optical Communication (DSOC) project aboard the Psyche spacecraft. The receiver system consists of a fiber interconnect, up to sixteen superconducting nanowire single-photon detectors (SNSPDs), and a field programmable gate array (FPGA) based receive modem. Previously, the receiver system architecture was described and test results without emulated link effects were presented. SNSPD device properties, which impact detection jitter and time delay, can limit the receiver dynamic range, especially when operating with varying flux rates (>10 dB) between detectors. Codeword error-rate curves with and without simulated clock drifts attributed to Doppler shift and space transmitter clock differences are presented. Results with ±66 ppm clock differences show minimal performance impact (<0.2 dB). Test results show that the receiver dynamic range (>28 dB) is limited by changing SNSPD detection delays at high photon flux rates.

optical communications↗

Real Time Photon-Counting Receiver for High Photon Efficiency Optical Communications

We present a scalable design for a photon-counting ground receiver based on superconducting nanowire single photon detectors (SNSPDs) and field programmable gate array (FPGA) real-time processing for applications to space-to-ground photon starved links, such as the Orion EM-2 Optical Communication Demonstration (O2O), and future deep space or low transmitter power missions. The receiver is designed to receive a serially concatenated pulse position modulation (SCPPM) waveform, which follows the Consultative Committee for Space Data Systems (CCSDS) Optical Communications Coding and Synchronization Red Book standard. The receiver design uses multiple individually fiber coupled, 80% detection efficiency commercial SNSPDs in parallel to scale to a required data rate, and is capable of achieving data rates up to 528 Mbps. For efficient fiber coupling from the telescope to the array of parallel detectors that can be scaled both to telescope aperture size and the number of detectors, we use either a single mode fiber (SMF) photonic lantern or a few-mode fiber (FMF) photonic lantern. In this paper we give an overview of the receiver system design, the characteristics of the photonic lanterns, the performance of the SNSPDs, and system level tests. We show that 40 Mbps can be received using a single SNSPD, and discuss aspects for scaling to higher data rates.

Vyhnalek, Brian E.↗

Real Time Photon-Counting Receiver for High Photon Efficiency Optical Communications

We present a scalable design for a photon-counting ground receiver based on superconducting nanowire single photon detectors (SNSPDs) and field programmable gate array (FPGA) real-time processing for applications to space-to-ground photon starved links, such as the Orion EM-2 Optical Communication Demonstration (O2O), and future deep space or low transmitter power missions. The receiver is designed to receive a serially concatenated pulse position modulation (SCPPM) waveform, which follows the Consultative Committee for Space Data Systems (CCSDS) Optical Communications Coding and Synchronization Red Book standard. The receiver design uses multiple individually fiber coupled, 80% detection efficiency commercial SNSPDs in parallel to scale to a required data rate, and is capable of achieving data rates up to 528 Mbps. For efficient fiber coupling from the telescope to the array of parallel detectors that can be scaled both to telescope aperture size and the number of detectors, we use either a single mode fiber (SMF) photonic lantern or a few-mode fiber (FMF) photonic lantern. In this paper we give an overview of the receiver system design, the characteristics of the photonic lanterns, the performance of the SNSPDs, and system level tests. We show that 40 Mbps can be received using a single SNSPD, and discuss aspects for scaling to higher data rates.

Vyhnalek, Brian E.↗

Integrated photonic Galton board and its application for photon counting

The Galton board is a desktop probability machine traditionally used to visualize the principles of statistical physics from classical particles. Here, we demonstrate a photonic Galton board that enables on-chip observation of statistics from single-photon interference. The photonic Galton board consists of a directional coupler matrix terminated by an array of superconducting nanowire detectors to provide spatiotemporal resolution. This design also allows for photon-number-resolving capability, making it suitable for high-speed photon counting. Our results demonstrate the compatibility between single-photon detector array and photonic integrated circuits, paving the way for implementing on-chip large-scale quantum optics experiments and photonic quantum computing.

Qin, Hezheng (ORCID:0009000139348800)↗

Infrared quantum ghost imaging of living and undisturbed plants

Quantum ghost imaging (QGI) is a method that measures absorption at extremely low light intensities. Nondegenerate QGI probes a sample at one wavelength while forming an image with correlated photons at a different wavelength. This spectral separation alleviates the need for imaging detectors with high sensitivity in the near-infrared (NIR) region, thereby reducing the required illumination intensity. Using NCam, a single-photon detector, we demonstrated nondegenerate QGI with unprecedented sensitivity and contrast, obtaining images of living plants with less than 1% light transmission. The plants experienced 3aW/cm 2 of light during imaging, orders of magnitude below starlight. This realization of QGI expands the method to extremely low-light bioimaging and imaging of light-sensitive samples, where minimizing illumination intensity is crucial to prevent phototoxicity or sample degradation.

47 OTHER INSTRUMENTATION↗

Detector Channel Combining Results from a High Photon Efficiency Optical Communications Link Test Bed

The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) is developing a low cost, scalable, photon counting receiver prototype for space-to-ground optical communications links. The receiver is being tested in a test bed that emulates photon-starved space-to-ground optical communication links. The receiver uses an array of single-pixel fiber-coupled superconducting nanowire single-photon detectors. The receiver is designed to receive the high photon efficiency serially concatenated pulse position modulation (SCPPM) waveform specified in the Consultative Committee for Space Data Systems (CCSDS) Optical Communications Coding and Synchronization Blue Book Standard. The optical receiver consists of an array of single-pixel superconducting nanowire detectors, analog phase shifters for channel alignment, digitizers for each detector channel, and digital processing of the received signal. An overview of the test bed and arrayed receiver system is given. Simulation and system characterization results are presented. The data rate increase of using a four-channel arrayed detector system over using one single pixel nanowire detector is characterized. Results indicate that a single-pixel detector is capable of receiving data at a rate of 40 Mbps and a four-channel arrayed detector system is capable of receiving data at a rate of 130 Mbps.

Downey, Jennifer N.↗

Detector Channel Combining Results from a High Photon Efficiency Optical Communications Link Test Bed

The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) is developing a low cost, scalable, photon-counting receiver prototype for space-to-ground optical communications links. The receiver is being tested in a test bed that emulates photon-starved space-to-ground optical communication links. The receiver uses an array of single-pixel fiber-coupled superconducting nanowire single-photon detectors. The receiver is designed to receive the high photon efficiency serially concatenated pulse position modulation (SCPPM) waveform specified in the Consultative Committee for Space Data Systems (CCSDS) Optical Communications Coding and Synchronization Blue Book Standard. The optical receiver consists of an array of single-pixel superconducting nanowire detectors, analog phase shifters for channel alignment, digitizers for each detector channel, and digital processing of the received signal. An overview of the test bed and arrayed receiver system is given. Simulation and system characterization results are presented. The data rate increase of using a four-channel arrayed detector system over using one single pixel nanowire detector is characterized. Results indicate that a single-pixel detector is capable of receiving data at a rate of 40 Mbps and a four-channel arrayed detector system is capable of receiving data at a rate of 130 Mbps.

Downey, Jennifer N.↗

High-frequency gravitational wave detection by the BREAD experiment

The use of experiments searching for light axion dark matter as high-frequency gravitational wave detectors has garnered increasing attention in recent years. We explore the capabilities of the Broadband Reflector Experiment for Axion Detection (BREAD) in probing the GW parameter space and study the directional dependence of its coverage. This detector can investigate frequencies ranging from 0.05 to 200 THz. We find that by employing single photon detectors, BREAD is sensitive to GWs with characteristic strains as low as 10 −21 at 0.1 THz and 10 −25 at 200 THz with a year exposure time, making it competitive with other proposals operating at similar frequencies.

axions↗

Implementation of quantum key distribution and quantum clock synchronization via time bin encoding

Quantum key distribution allows for a provably secure transmission of cryptographic keys over an optical channel. Encoded polarization states or time-bin degree of freedom have been used for successful demonstrations. However, photon losses in long fibers, slow single photon detectors, and detector dark counts significantly limit the overall bit rate. Improving key throughput and reducing the overhead of key reconciliation remain as major challenges. Methods which utilize multiple time bins allow for multiple key bits to be encoded in a single photon, thus increasing the fidelity of transmitted keys and decreasing the overhead of key reconciliation in real-world conditions. Previous implementations of these methods required that Alice and Bob share a time reference by sharing a dedicated classical channel used for synchronization. This work presents a technique that allows two parties to exchange time-bin encoded photons without the need for synchronized time references. Our technique uses a framing protocol which allows Alice to encode a time reference along with a key which is determined by Alice before transmission. Security can be achieved by monitoring the visibility of a pair of Franson interferometers, using decoy pulses and measuring the round trip time between Alice and Bob. The bit rate of this technique is limited only by the recovery time of the detector and the speed of the modulation electronics. We experimentally demonstrate a raw bit rate of 5Mb/s over an optical channel with 55dB of loss, which is competitive with current research. We also demonstrate absolute timing synchronization with an accuracy of 20ps.

encryption↗

Photon-to-Digital Converters for Neutron Imaging Instruments (Final Report)

Oak Ridge National Laboratory (ORNL) collaborated with the Université de Sherbrooke (UdeS) to design a modular and scalable tile of innovative digital photodetectors called Photon-to-Digital Converters (PDC) and the required subsystems to demonstrate the feasibility of large area single-photon detectors to support high-resolution, depth-of-interaction, fast neutron radiography based on scintillation detectors. The goal is to demonstrate the advantages of using PDC over conventional Silicon Photomultiplier (SiPM) for neutron imaging systems. The basic building blocks of analog SiPM and PDC are Single-Photon Avalanche Photodiodes (SPAD). The main difference between conventional SiPMs and PDCs, is in the fact that analog SiPMs sum the charge produced by individual SPAD passively, while in PDCs each SPAD is read out individually by an active electronic circuit. Hence, PDCs provide a direct photon-to-bit conversion where a logic “1” means that there was a detection in a given SPAD. Conversely, an analog SiPM requires a sophisticated preamplifier (current amplifiers or transimpedance amplifier) followed by a shaping amplifier and an analog-to-digital converter. Moreover, since the charge from each SPAD varies slightly, the passive sum of the analog SiPM will have signal fluctuations for the same amount of photon detected. This is one of many issues that is completely eliminated by individual one-to-one SPAD read out in PDCs. The large area required for scintillator readouts for neutron imaging is such that the output capacitance of a large area of SiPM arrays is very high. This creates a burden on the signal-to-noise optimization with respect to the power budget. For PDC, the power consumption is dictated by rate of the incident photon flux, or in photon-starved environments, the dark noise rate of the SPAD array. In other words, the power consumption in the absence of events is extremely low. Hence, the power consumption of a PDC read out system is much lower than its analog counterpart. Further, the large SiPM capacitance may introduce signal distortions on the scintillator fast rise or decay time with undesired effects on timing and pulse shape discrimination. The problem is absent in PDCs, as their readout is independent on device capacitance. UdeS is the world leader in 3D vertical integration of frontside illuminated SPAD arrays over CMOS readouts. These capabilities allow future production of “3D PDC” with maximum photosensitive fill factor and electronic functionalities tailored to the application. UdeS' vast knowledge of SPADs and CMOS design made the team an ideal collaborator in the development of large area high-resolution fast neutron radiography.

42 ENGINEERING↗

Nonlocal subpicosecond delay metrology using spectral quantum interference

Precise knowledge of position and timing information is critical to support elementary protocols such as entanglement swapping on quantum networks. While approaches have been devised to use quantum light for such metrology, they largely rely on time-of-flight (ToF) measurements with single-photon detectors and, therefore, are limited to picosecond-scale resolution owing to detector jitter. In this work, we demonstrate an approach to distributed sensing that leverages phase modulation to map changes in the spectral phase to coincidence probability, thereby overcoming the limits imposed by single-photon detection. By extracting information about the joint biphoton phase, we measure a generalized delay—the difference in signal–idler arrival, relative to local radio frequency (RF) phase modulation. For nonlocal ranging measurements, we achieve (2$σ$) precision of ±0.04 ps and for measurements of the relative RF phase, (2$σ$) precision of ±0.7°. We complement this fine timing information with ToF data from single-photon time-tagging to demonstrate absolute measurement of time delay. By relying on off-the-shelf telecommunications equipment and standard quantum resources, this approach has the potential to reduce overhead in practical quantum networks.

42 ENGINEERING↗

NASA Tech Briefs, March 2007

Topics include: Advanced Systems for Monitoring Underwater Sounds; Wireless Data-Acquisition System for Testing Rocket Engines; Processing Raw HST Data With Up-to-Date Calibration Data; Mobile Collection and Automated Interpretation of EEG Data; System for Secure Integration of Aviation Data; Servomotor and Controller Having Large Dynamic Range; Digital Multicasting of Multiple Audio Streams; Translator for Optimizing Fluid-Handling Components; AIRSAR Web-Based Data Processing; Pattern Matcher for Trees Constructed From Lists; Reducing a Knowledge-Base Search Space When Data Are Missing; Ground-Based Correction of Remote-Sensing Spectral Imagery; State-Chart Autocoder; Pointing History Engine for the Spitzer Space Telescope; Low-Friction, High-Stiffness Joint for Uniaxial Load Cell; Magnet-Based System for Docking of Miniature Spacecraft; Electromechanically Actuated Valve for Controlling Flow Rate; Plumbing Fixture for a Microfluidic Cartridge; Camera Mount for a Head-Up Display; Core-Cutoff Tool; Recirculation of Laser Power in an Atomic Fountain; Simplified Generation of High-Angular-Momentum Light Beams; Imaging Spectrometer on a Chip; Interferometric Quantum-Nondemolition Single-Photon Detectors; Ring-Down Spectroscopy for Characterizing a CW Raman Laser; Complex Type-II Interband Cascade MQW Photodetectors; Single-Point Access to Data Distributed on Many Processors; Estimating Dust and Water Ice Content of the Martian Atmosphere From THEMIS Data; Computing a Stability Spectrum by Use of the HHT; Theoretical Studies of Routes to Synthesis of Tetrahedral N4; Estimation Filter for Alignment of the Spitzer Space Telescope; Antenna for Measuring Electric Fields Within the Inner Heliosphere; Improved High-Voltage Gas Isolator for Ion Thruster; and Hybrid Mobile Communication Networks for Planetary Exploration.

Source record↗

Single-photon detection using high-temperature cuprate superconductors

The detection of individual quanta of light is important for quantum computation, fluorescence lifetime imaging, single-molecule detection, remote sensing, correlation spectroscopy, and more. Thanks to their broadband operation, high detection efficiency, exceptional signal-to-noise ratio, and fast recovery times, superconducting nanowire single-photon detectors (SNSPDs) have become a critical component in these applications. The operation of SNSPDs based on conventional superconductors, which have a low critical temperature (T c ), requires costly and bulky cryocoolers. This motivated exploration of other superconducting materials with higher T c that would enable single-photon detection at elevated temperatures, yet this task has proven exceedingly difficult. Here we show that with proper processing, high-T c cuprate superconductors can meet this challenge. We fabricated superconducting nanowires (SNWs) out of thin flakes of Bi 2 Sr 2 CaCu2O 8+δ and La 1.55 Sr 0.45 CuO 4 /La 2 CuO 4 (LSCO-LCO) bilayer films and demonstrated their single-photon response up to 25 and 8 K, respectively. The single-photon operation is revealed through the linear scaling of the photon count rate (PCR) on the radiation power. Both of our cuprate-based SNSPDs exhibited single-photon sensitivity at the technologically-important 1.5 μm telecommunications wavelength. Our work expands the family of superconducting materials for SNSPD technology, opens the prospects of raising the temperature ceiling, and raises important questions about the underlying mechanisms of single-photon detection by unconventional superconductors.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Entanglement Capacity Estimates and Throughput Measurements of Quantum Channels

The throughput is an important performance metric of entangled qubit distribution quantum networks, and may be characterized by the number of distributed entangled qubit pairs per second (ebps). It is measured over physical quantum network connections using specialized instruments, including photonic entanglement sources and single photon detectors. Extensive theory has been developed to estimate the entangled qubit capacity of quantum channels using abstractions of physical connections. These two quantities both characterize the throughput performance but in different ways, and typically have been hard to relate to each other in concrete terms, in part due to the lack of precise measurements with matching analytical models and derivations. We describe measurements on a physical testbed with fiber connections of lengths 0-75 kilometers. We obtain the normalized analytic capacity estimates using the transmissivity approximations derived using single photon coincidence measurements, and convert them to bounds on throughput (measured in ebps) using a multiplier derived from co-located detector measurements. The results indicate consistent throughput measurements upper-bounded by their analytical capacity estimates across all connections. We show that previous capacity estimates using light measurements are below ebps measurements for some connections, due to the inclusion of non-representative decrease of light levels outside C-band with distance.

Rao, Nageswara↗

Performance of A Real-Time Photon Counting Optical Receiver in the Presence of Emulated Channel Fading

Free-space optical communication links with terrestrial ground stations experience fading due to atmospheric scintillation and beam pointing. Fiber-coupled receiver systems experience additional fading at the interface between the fiber and free-space optics of the telescope. The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) has characterized a real-time photon-counting optical ground receiver system with an atmospheric fade emulation system. The receiver system is comprised of a fiber interconnect, an array of superconducting nanowire single photon detectors (SNSPDs), and a field programmable gate array (FPGA) based receive modem. Two fiber interconnect/detector architectures have been studied. One architecture uses a 70-mode photonic lantern coupled to seven single pixel SNSPDs. The other architecture uses a 10-mode few-mode fiber (FMF) coupled to a 15-pixel SNSPD array. The receiver system complies with the Consultative Committee for Space Data Systems (CCSDS) Optical Communications High Photon Efficiency Coding and Synchronization Standard, which uses serially concatenated convolutionally coded pulse-position modulation (SCPPM). The CCSDS standard is designed for use in low photon flux missions, including the Orion Artemis-II Optical (O2O) communications demonstration. The standard utilizes a convolutional symbol interleaver which can be resized to mitigate different fades. The fade emulation system employed in this work emulates scintillation-induced, pointing-induced, and coupling-induced fading. This paper gives an overview of the real-time optical receiver system and the fade emulation system. It presents tests results which show the impact of fading on the performance on the receiver. The test results show that in the presence of channel fading, the 70-mode photonic lantern outperforms the 10-mode FMF under higher (D/r_0=9) turbulence conditions due to high fiber-coupling-induced fading and fiber coupling loss on the 10-mode FMF. When operating in lower turbulence (D/r_0=4), the 10-mode FMF outperforms the 70-mode photonic lantern. The paper also shows a larger convolutional interleaver improves the system performance as long as the receiver does not lose acquisition.

optical communications↗

Performance of a real-time photon counting optical receiver in the presence of emulated channel fading

Free-space optical communication links with terrestrial ground stations experience fading due to atmospheric scintillation and beam pointing. Fiber-coupled receiver systems experience additional fading at the interface between the fiber and free-space optics of the telescope. The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) has characterized a real-time photon-counting optical ground receiver system with an atmospheric fade emulation system. The receiver system is comprised of a fiber interconnect, an array of superconducting nanowire single photon detectors (SNSPDs), and a field programmable gate array (FPGA) based receive modem. Two fiber interconnect/detector architectures have been studied. One architecture uses a 70-mode photonic lantern coupled to seven single pixel SNSPDs. The other architecture uses a 10-mode few-mode fiber (FMF) coupled to a 15-pixel SNSPD array. The receiver system complies with the Consultative Committee for Space Data Systems (CCSDS) Optical Communications High Photon Efficiency Coding and Synchronization Standard, which uses serially concatenated convolutionally coded pulse-position modulation (SCPPM). The CCSDS standard is designed for use in low photon flux missions, including the Orion Artemis-II Optical (O2O) communications demonstration. The standard utilizes a convolutional symbol interleaver which can be resized to mitigate different fades. The fade emulation system employed in this work emulates scintillation-induced, pointing-induced, and coupling-induced fading. This paper gives an overview of the real-time optical receiver system and the fade emulation system. It presents tests results which show the impact of fading on the performance on the receiver. The test results show that in the presence of channel fading, the 70-mode photonic lantern outperforms the 10-mode FMF under higher (D/r_0=9) turbulence conditions due to high fiber-coupling-induced fading and fiber coupling loss on the 10-mode FMF. When operating in lower turbulence (D/r_0=4), the 10-mode FMF outperforms the 70-mode photonic lantern. The paper also shows a larger convolutional interleaver improves the system performance as long as the receiver does not lose acquisition.

optical communications↗

Refinement and Modeling of a Blackbody-Based Calibration Method in the InfraBREAD Detector

The Broadband Reflector Experiment for Axion Detection (BREAD) is an ongoing collaboration searching for the conversion of yet undiscovered axion-like dark matter particles to photons in the presence of a magnetic field. InfraBREAD, an experiment of BREAD, uses a superconducting nanowire single photon detector (SNSPD), a high-efficiency and low-noise device, to specifically detect infrared-range photons produced by $\mathcal{O}$(eV) axion-like particles. The unique BREAD reflector setup allows for the focusing of converted signal photons to a 1mm $\times$ 1mm SNSPD. However, when the detector is cooled to cryogenic temperatures during operation, uneven thermal contraction of reflector components may lead to a small shift in the location of the focal spot. A novel calibration method using blackbody radiation is proposed to locate the true focal spot of the detector \textit{in situ}. Through ray tracing simulations done in FRED Optical Engineering Software, this method is demonstrated to locate the focus to within $\SI{50}{\micro\metre}$ in the $z$ dimension.

Rao, Shardul↗

Refinement and Modeling of a Blackbody-Based Calibration Method in the InfraBREAD Detector

The Broadband Reflector Experiment for Axion Detection (BREAD) is an ongoing experiment searching for the conversion of yet undiscovered axion-like dark matter particles to photons in the presence of a magnetic field. InfraBREAD, a sub-experiment of BREAD, uses a superconducting nanowire single photon detector (SNSPD), a high-efficiency and low-noise device, to specifically detect infrared-range photons produced by $\mathcal{O}$(eV) axion-like particles. The unique BREAD reflector setup allows for the focusing of all converted signal photons to a 1mm $\times$ 1mm SNSPD. However, when the detector is cooled to cryogenic temperatures during operation, uneven thermal contraction of reflector components may lead to a small shift in the location of the focal spot. A novel calibration method using blackbody radiation is proposed to locate the true focal spot of the detector \textit{in situ}. Through ray tracing simulations done in FRED Optical Engineering Software, this method is demonstrated to locate the focus to within 50 $\mu$m in three dimensions.

Rao, Shardul↗