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Results for “homodyne detection”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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52 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Field test of continuous-variable quantum key distribution with a true local oscillator

A continuous-variable quantum key distribution (CV QKD) using a true local (located at the receiver) oscillator (LO) has been proposed to remove any possibility of side-channel attacks associated with transmission of the LO as well as reduce the cross-pulse contamination. Here we report an implementation of true LO-CV QKD using “off-the-shelf” components and conduct QKD experiments using the fiber optical network at Oak Ridge National Laboratory. A phase reference and quantum signal are time multiplexed and then wavelength division multiplexed with the classical communications that “coexist” with each other on a single optical network fiber. Importantly, this is the first demonstration of CV QKD with a receiver-based true LO over a deployed fiber network, a crucial step for its application in real-world situations.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2021

Phase Demodulation by Frequency Chirping in Coherence Microwave Photonic Interferometry

This paper presents a signal processing method to demodulate the optical interference phase of cascaded individual optical fiber intrinsic Fabry-Perot interferometric (IFPI) sensors in a coherent microwave-photonic interferometry (CMPI) distributed sensing system. The new method utilizes the chirp effect of electro-optic modulator (EOM) to create a quasi-quadrature optical interference phase shift between two adjacent pulses which correspond to two adjacent reflection points in the time domain. The phase shift can be controlled by adjusting the bias voltage that is applied to the EOM. The interference phase is calculated by elliptically fitting the phase shift. The interference phase change is proportional to the optical path difference (OPD) change of the interferometer, and the sign can be used to differentiate the increase or decrease of the OPD. The method is demonstrated for distributed strain sensing, showing good linearity, high resolution and large dynamic range.

42 ENGINEERING↗
NASA NTRS1972

Optical communication theory.

An introduction is provided to the important ideas involved in the design and the evaluation of optical communication systems which transmit digital or analog data. Field representations are discussed together with background noise, a detector statistical model, quantum receivers, and turbulent and scatter channels. Free-space channels are considered, taking into account heterodyne systems, preamplifier and homodyne systems, direct-detection systems, and optimum quantum systems.

Hoversten, E. V.↗
NASA NTRS1989

Fiber optic links for microwave/millimeter-wave systems

Recent advances in device technology for microwave/mm-wave (M/MMW) analog fiber-optic communication systems are surveyed, with discussion of system parameters, design optimization methods, and hardware selection and manufacturing considerations. Particular attention is given to 1-km-link systems operating at 21, 30, and 12 GHz for satellite-communication, electronic-warfare, and radar applications. The design and fabrication simplicity of direct modulation is weighed against the wide bandwidth, low distortion, and mm-wave and frequency operation advantages of external modulation. Homodyne or heterodyne coherent detection is shown to improve system S/N by 10-20 dB over conventional detection methods. Diagrams, drawings, photographs, and graphs of typical performance data are included.

Pan, J. J.↗
NASA NTRS2019

Spectrally Resolved Synthetic Aperture Imaging Interferometer: Final Report of NASA Innovative Advanced Concepts - Phase 1 Study

The Spectrally Resolved Synthetic-Aperture Imaging Interferometer (SRSAII) is a system proposed to provide high-resolution and high-sensitivity measurements of astronomical objects. SRSAII uses long baseline interferometric methods to achieve the resolution and low-noise, high time-precision detection to achieve the sensitivity. The primary goal of the SRSAII study was to lay out a framework for using new optical physics technologies to directly resolve, both spatially and spectrally, the disk of an exoplanet. In addition to the ambitious goal of directly resolving an exoplanet, the SRSAII team also sought to identify science opportunities achievable with intermediate system configurations which may offer resolution significantly higher than the current state of the art, but insufficient for direct resolution of an exoplanetary disk. An operational SRSAII system can function with essentially arbitrarily large baselines, achieving correspondingly high angular resolution. The primary limitation occurs in the system sensitivity, which became the major technical focus for study. In this report, we compare the predicted performance (sensitivity in SNR (Signal-to-Noise Ratio) along with angular resolution) of three interferometric techniques: direct detection (also known as homodyne interferometry), multi-channel intensity interferometry (using the Hanbury Brown and Twiss effect), and multi-channel heterodyne interferometry (using an optical frequency comb as a local oscillator). Additionally, quantum-assisted interferometry is also explored as a prospective enhancement of established methods. This report presents a survey of the technologies that enable the SRSAII techniques - optical frequency combs, single photon detectors, and photonic integrated circuits. These technologies are the basis of methods critical to SRSAII's success: precision timing, length and frequency metrology, sensitive photodetection, fine-scale wavelength filtering, and dense multi-channel operation. Lastly, we give some notional performance metrics and propose some possible experimental observations.

High Resolultion↗
NASA NTRS1992

Method and apparatus for determining the physical properties of materials using dynamic light scattering techniques

A system for determining the physical properties of materials through the use of dynamic light scattering is disclosed. The system includes a probe, a laser source for directing a laser beam into the probe, and a photodetector for converting scattered light detected by the probe into electrical signals. The probe includes at least one optical fiber connected to the laser source and a second optical fiber connected to the photodetector. Each of the fibers may adjoin a gradient index microlens which is capable of providing a collimated laser beam into a scattering medium. The position of the second optical fiber with respect to the optical axis of the probe determines whether homodyne or self-beating detection is provided. Self-beating detection may be provided without a gradient index microlens. This allows a very small probe to be constructed which is insertable through a hypodermic needle or the like into a droplet extending from such a needle. A method of detecting scattered light through the use of a collimated, Gaussian laser beam is also provided. A method for controlling the waist and divergence of the optical field emanating from the free end of an optical fiber is also provided.

Dhadwal, Harbans S.↗
DOE OSTI2024

Quantum enhanced magneto-optical microscopy and spectroscopy

A system comprising a nonlinear medium (NLM), an optical transduction module, a dual homodyne detector and a processor is provided. The NLM receives at least a pump beam and issues the pump, probe and conjugate beams, where the beams are linearly polarized. Optics route the probe, the conjugate or both beams to the sample. The sample imparts polarization rotation to light that interacts therewith. The optical transduction module imparts to the interacted light an optical phase shift that is a 1:1 transduction of the polarization rotation, where at least one of the probe light or the conjugate light carries the imparted optical phase shift. The processor obtains the optical-phase shift based on respective detection signals from the dual homodyne detector and determines, based on the obtained optical-phase shift, at least one of a Faraday polarization rotation, a Kerr polarization rotation or a spin noise spectrum.

Lawrie, Benjamin J.↗
DOE OSTI2024

Boson sampling with Gaussian input states: Toward efficient scaling and certification

A universal quantum computer of large scale is not available yet, however, intermediate models of quantum computation would still permit demonstrations of a quantum computational advantage over classical computing and could challenge the Extended Church-Turing Thesis. One of these models based on single photons interacting via linear optics is called Boson Sampling. Although Boson Sampling was demonstrated and the threshold to claim quantum computational advantage was achieved, the question of how to scale up Boson Sampling experiments remains. To make progress with this problem, here we present a practically achievable pathway to scale Boson Sampling experiments by combining continuous-variable quantum information and temporal encoding. Here, we propose the combination of switchable dual-homodyne and single-photon detections, the temporal loop technique, and scattershot-based Boson Sampling. We detail the required assumptions for concluding computational hardness for this configuration. Furthermore, this particular combination of techniques moves towards an efficient scaling and certification of Boson Sampling, all in a single experimental setup.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1994

Conceptual radiometer design studies for Earth observations from low Earth orbit

A conceptual radiometer design study was performed to determine the optimum design approach for spaceborne radiometers in low Earth orbit. Radiometric system configurations which included total power radiometers, unbalanced Dicke radiometers, and balanced Dicke, or as known as noise injection, radiometers were studied. Radiometer receiver configurations which were analyzed included the direct detection radiometer receiver, the double sideband homodyne radiometer receiver, and the single sideband heterodyne radiometer receiver. Radiometer system performance was also studied. This included radiometric sensitivity analysis of the three different radiometer system configurations studied. Both external and internal calibration techniques were analyzed. An accuracy analysis with and without mismatch losses was performed. It was determined that the balanced Dicke radiometer system configuration with direct detection receivers and external calibrations was optimum where frequent calibration such as once per minute were not feasible.

Harrington, Richard F.↗
NASA NTRS1984

Demodulator for AM and SSB-SC Signals

Compatible linear demodulator (CLD) detects either amplitude modulation (AM) or single-sideband suppressed-carrier (SSB-SC) modulation. Carrier recovery homodyne product detector designed for voice communication but easily scaled to other frequencies.

Hearn, C. P.↗
NASA NTRS1991

Miniaturized fiber-optic Michelson-type interferometric sensors

A novel, miniaturized Michelson-type fiber-optic interferometric sensor that is relatively insensitive to temperature drifts is presented. A fused-biconical tapered coupler is cleaved immediately after the coupled length and polished down to the region of the fused cladding, but short of the interaction region. The end of one core is selectively coated with a reflective surface and is used as the reference arm; the other core serves as the sensing arm. The detection of surface acoustic waves, microdisplacements, and magnetic fields is reported. The sensor is shown to be highly stable in comparison to a classic homodyne, uncompensated Michelson interferometer, and signal-to-noise ratios of 65 dB have been obtained.

Murphy, Kent A.↗
DOE OSTI2024

Axion detection via superfluid 3 He ferromagnetic phase and quantum measurement techniques

We propose to use the nuclear spin excitation in the ferromagnetic A 1 phase of the superfluid 3 He for the axion dark matter detection. This approach is striking in that it is sensitive to the axion-nucleon coupling, one of the most important features of the QCD axion introduced to solve the strong CP problem. We review a quantum mechanical description of the nuclear spin excitation and apply it to the estimation of the axion-induced spin excitation rate. We also describe a possible detection method of the spin excitation in detail and show that the combination of the squeezing of the final state with the Josephson parametric amplifier and the homodyne measurement can enhance the sensitivity. It turns out that this approach gives good sensitivity to the axion dark matter with the mass of $\mathcal{O}$(1) μeV depending on the size of the external magnetic field. We estimate the parameters of experimental setups, e.g., the detector volume and the amplitude of squeezing, required to reach the QCD axion parameter space.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Negative Index Metamaterial Lens for Subwavelength Microwave Detection

Metamaterials are engineered periodic structures designed to have unique properties not encountered in naturally occurring materials. One such unusual property of metamaterials is the ability to exhibit negative refractive index over a prescribed range of frequencies. A lens made of negative refractive index metamaterials can achieve resolution beyond the diffraction limit. This paper presents the design of a metamaterial lens and its use in far-field microwave imaging for subwavelength defect detection in nondestructive evaluation (NDE). Theoretical formulation and numerical studies of the metamaterial lens design are presented followed by experimental demonstration and characterization of metamaterial behavior. Finally, a microwave homodyne receiver-based system is used in conjunction with the metamaterial lens to develop a far-field microwave NDE sensor system. A subwavelength focal spot of size 0.82λ was obtained. The system is shown to be sensitive to a defect of size 0.17λ × 0.06λ in a Teflon sample. Consecutive positions of the defect with a separation of 0.23λ was resolvable using the proposed system.

47 OTHER INSTRUMENTATION↗
DOE OSTI2026

Photon temporal-mode readout for inference of neutron star merger remnant gravitational waves

Gravitational waves emitted after neutron star binary coalescences and the information they carry about dense matter are a high-priority target for next-generation detectors. Even though such detectors are expected to observe millions of signals, detectable postmerger emission will remain rare. Here, in this work, we explore postmerger detectability and inference through an alternative detector readout scheme for data dominated by quantum-noise, which is the case above 1 kHz; photon-counting. In such a readout, signals and noise become quantized into discrete distributions corresponding to the detection of single photons measured in a chosen basis of modes. Through simulated data, we demonstrate that photon counting can be efficient even for weak signals. We find ∼1 in 100 signals with a postmerger signal-to-noise ratio of 0.2 can result in a single photon and thus be detected. Furthermore, after 2 ×10 4 signals—equivalent to 10 −2 to 1.5 years of observation—photon counting results in a twofold improvement in the measurement of the radius of a 1.6⁢𝑀 ⊙ neutron star. Constraints can be further tightened if the detector classical noise is reduced. Photon counting offers a promising alternative to traditional homodyne readout techniques for extracting information from low signal-to-noise ratio postmerger signals.

gravitational wave detection↗
DOE OSTI2020

Identifications and classifications of human locomotion using Rayleigh-enhanced distributed fiber acoustic sensors with deep neural networks

Abstract This paper reports on the use of machine learning to delineate data harnessed by fiber-optic distributed acoustic sensors (DAS) using fiber with enhanced Rayleigh backscattering to recognize vibration events induced by human locomotion. The DAS used in this work is based on homodyne phase-sensitive optical time-domain reflectometry (φ-OTDR). The signal-to-noise ratio (SNR) of the DAS was enhanced using femtosecond laser-induced artificial Rayleigh scattering centers in single-mode fiber cores. Both supervised and unsupervised machine-learning algorithms were explored to identify people and specific events that produce acoustic signals. Using convolutional deep neural networks, the supervised machine learning scheme achieved over 76.25% accuracy in recognizing human identities. Conversely, the unsupervised machine learning scheme achieved over 77.65% accuracy in recognizing events and human identities through acoustic signals. Through integrated efforts on both sensor device innovation and machine learning data analytics, this paper shows that the DAS technique can be an effective security technology to detect and to identify highly similar acoustic events with high spatial resolution and high accuracies.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRSDate not supplied

Navigation Doppler Lidar Signal Processing Architecture and Algorithms

A coherent Doppler lidar has been developed to address the need for a high-performance, compact, and cost-effective velocity and altitude sensor onboard landing vehicles. One of the core subsystems within NDL is its signal processing architecture. The primary function of this subsystem is to digitize the analog output of the homodyned signal received from the photo-diode associated with each telescope, process this signal in the frequency domain, and then turn this information into velocity and range measurements. A secondary function of this subsystem is to setup and control the internal components within NDL and to enable the instrument to interface with external systems by receiving commands, sending telemetry, and synchronizing its measurements with external clocks and pulses. This paper will give an overview of the signal processing architecture within NDL. This will include a discussion on its fundamental processing components and the core signal processing algorithms. Command, telemetry and internal component controls will also be discussed as will how the signal processing architecture has also evolved over the years of development. We will discuss provisions for robust operation including Triple-Mode Redundancy (TMR) within NDL’s Field Programmable Gate Array (FPGA) and storage elements, a fault-tolerant boot process, and Error Detection and Correction (EDAC) on the Static Random-Access Memories (SRAMs). Finally, we conclude this paper with how this architecture could continue to evolve.

Doppler Lidar↗