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Results for “frequency conversion”

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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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

Spike train generation and current-to-frequency conversion in silicon diodes

A device physics model is developed to analyze spontaneous neuron-like spike train generation in current driven silicon p(+)-n-n(+) devices in cryogenic environments. The model is shown to explain the very high dynamic range (0 to the 7th) current-to-frequency conversion and experimental features of the spike train frequency as a function of input current. The devices are interesting components for implementation of parallel asynchronous processing adjacent to cryogenically cooled focal planes because of their extremely low current and power requirements, their electronic simplicity, and their pulse coding capability, and could be used to form the hardware basis for neural networks which employ biologically plausible means of information coding.

Coon, D. D.↗
DOE OSTI2021

Microwave-optical quantum frequency conversion

Photons at microwave and optical frequencies are principal carriers for quantum information. While microwave photons can be effectively controlled at the local circuit level, optical photons can propagate over long distances. High-fidelity conversion between microwave and optical photons will allow the distribution of quantum states across different quantum technology nodes and enhance the scalability of hybrid quantum systems toward a future “Quantum Internet.” Despite a frequency difference of five orders of magnitude, there has been significant progress recently toward the transfer between microwave and optical photons with steadily improved efficiency in a coherent and bidirectional manner. In this review, we summarize this progress, emphasizing integrated device approaches, and provide a perspective for device implementation that enables quantum state transfer and entanglement distribution across microwave and optical domains.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2022

Precise electron beam-based target-wavelength trimming for frequency conversion in integrated photonic resonators

We demonstrate post-fabrication target-wavelength trimming with a gallium phosphide on a silicon nitride integrated photonic platform using controlled electron-beam exposure of hydrogen silsesquioxane cladding. A linear relationship between the electron-beam exposure dose and resonant wavelength red-shift enables deterministic, individual trimming of multiple devices on the same chip to within 30 pm of a single target wavelength. Second harmonic generation from telecom to near infrared at a target wavelength is shown in multiple devices with quality factors on the order of 10 4 . Post-fabrication tuning is an essential tool for targeted wavelength applications including quantum frequency conversion.

Thiel, Lillian↗
DOE OSTI2025

Photon–photon chemical thermodynamics of frequency conversion processes in highly multimode systems

Abstract Frequency generation in highly multimode nonlinear optical systems is inherently a complex process, giving rise to an exceedingly convoluted landscape of evolution dynamics. While predicting and controlling the global conversion efficiencies in such nonlinear environments has long been considered impossible, here, we formally address this challenge even in scenarios involving a very large number of spatial modes. By utilizing fundamental notions from optical statistical mechanics, we develop a universal theoretical framework that effectively treats all frequency components as chemical reactants/products, capable of undergoing optical thermodynamic reactions facilitated by a variety of multi-wave mixing effects. These photon–photon reactions are governed by conservation laws that directly determine the optical temperatures and chemical potentials of the ensued chemical equilibria for each frequency species. In this context, we develop a comprehensive stoichiometric model and formally derive an expression that relates the chemical potentials to the optical stoichiometric coefficients, in a manner akin to atomic/molecular chemical reactions. This advancement unlocks new predictive capabilities that can facilitate the optimization of frequency generation in highly multimode photonic arrangements, surpassing the limitations of conventional schemes that rely exclusively on nonlinear optical dynamics. Notably, we identify a universal regime of Rayleigh–Jeans thermalization where an optical reaction at near-zero optical temperatures can promote the complete and entropically irreversible conversion of light to the fundamental mode at a target frequency. Our theoretical results are corroborated by numerical simulations in settings where second-harmonic generation, sum-frequency generation and four-wave mixing processes can manifest.

Optics↗
NASA NTRS2001

Frequency conversion system

Laser diode pumped mid-IR wavelength sources include at least one high power, near-IR wavelength, injection and/or sources wherein one or both of such sources may be tunable providing a pump wave output beam to a quasi-phase matched (QPM) nonlinear frequency mixing (NFM) device. The NFM device may be a difference frequency mixing (DFM) device or an optical parametric oscillation (OPO) device. Wavelength tuning of at least one of the sources advantageously provides the ability for optimizing pump or injection wavelengths to match the QPM properties of the NFM device enabling a broad range of mid-IR wavelength selectivity. Also, pump powers are gain enhanced by the addition of a rare earth amplifier or oscillator, or a Raman/Brillouin amplifier or oscillator between the high power source and the NFM device. Further, polarization conversion using Raman or Brillouin wavelength shifting is provided to optimize frequency conversion efficiency in the NFM device.

Sanders, Steven↗
DOE OSTI2024

High‐Order Nonlinear Frequency Conversion in Transparent Conducting Oxide Thin Films

The study of conductive oxides has gained momentum within the photonics community due to their unique linear and nonlinear optical properties. Despite recent experiments reporting on high harmonic generation from thin films, the optical/electronic behavior of these compounds at the nanoscale is still not fully understood due to the lack of a suitable theoretical model. In the present work, aluminum zinc oxide is excited near its epsilon-near-zero crossing point using incident femtosecond pulses having peak power densities in the 1 TW cm −2 range. A relatively efficient frequency up-conversion including even and odd harmonics up to the seventh order is observed. A hydrodynamic-Maxwell theoretical approach is adopted, capable of simultaneously taking into account linear and nonlinear dispersions, nonlocal effects, surface, magnetic, and bulk nonlinearities in a spectral region that spans over two and a half octaves from the UV to the NIR region. The study enables a deeper understanding of the fundamental material parameters regulating optical nonlinearities, providing important insights to engineer this class of materials for applications in sensing, ultra-fast physics, and spectroscopy.

material modeling↗
NASA NTRS1985

Efficient frequency conversion of laser sources in nonlinear crystals

The use of nonlinear crystals to extend the frequency range of solid-state laser sources is proposed. The harmonic generation of high-average-power laser sources and CW-laser-sources nonlinear crystals is considered. The development of Nd:YAG pumped parametric oscillators and optical parametric amplifiers using LiNbO3 or AgGaS2 is studied. The LiNbO3 oscillator has tunable output over the 1.4-4.0 micron range and is applicable for remote sensing measurements of molecules and of humidity and temperature; AgGaS2 oscillators provide the potential for 3-15 micron infrared generation. Advances in material synthesis techniques related to the design and synthesis of nonlinear media are discussed. Various procedures for the synthesis of nonlinear crystals are described.

Byer, R. L.↗
DOE OSTI2020

Axion dark matter detection by superconducting resonant frequency conversion

We propose an approach to search for axion dark matter with a specially designed superconducting radio frequency cavity, targeting axions with masses ma ≲ 10 -6 eV. Our approach exploits axion-induced transitions between nearly degenerate resonant modes of frequency ~ GHz. A scan over axion mass is achieved by varying the frequency splitting between the two modes. Compared to traditional approaches, this allows for parametrically enhanced signal power for axions lighter than a GHz. The projected sensitivity covers unexplored parameter space for QCD axion dark matter for 10 -8 eV ≲ ma ≲ 10 -6 eV and axion-like particle dark matter as light as ma~ 10 -14 eV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Optomechanical ring resonator for efficient microwave-optical frequency conversion

Phonons traveling in solid-state devices are emerging as a universal excitation for coupling different physical systems. Phonons at microwave frequencies have a similar wavelength to optical photons in solids, enabling optomechanical microwave-optical transduction of classical and quantum signals. It becomes conceivable to build optomechanical integrated circuits (OMIC) that guide both photons and phonons and interconnect photonic and phononic devices. Here, we demonstrate an OMIC including an optomechanical ring resonator (OMR), where co-resonant infrared photons and GHz phonons induce significantly enhanced interconversion. The platform is hybrid, using wide bandgap semiconductor gallium phosphide (GaP) for waveguiding and piezoelectric zinc oxide (ZnO) for phonon generation. The OMR features photonic and phononic quality factors of >1 × 10 5 and 3.2 × 10 3 , respectively. The optomechanical interconversion between photonic modes achieved an internal conversion efficiency $η_i$ = (2.1 ± 0.1)% and a total device efficiency $η_{tot}$ = 0.57 x 10 -6 at a low acoustic pump power of 1.6 mW. The efficient conversion in OMICs enables microwave-optical transduction for quantum information and microwave photonics applications.

42 ENGINEERING↗
NASA NTRS1992

Negative Differential Resistance (NDR) frequency conversion with gain

The dependence of the I-V characteristic of the negative differential resistance (NDR) devices on the power level and frequency of the rf input signal has been theoretically analyzed with a modified large- and small-signal nonlinear circuit analysis program. The NDR devices we used in this work include both the tunnel diode (without the antisymmetry in the I-V characteristic) and resonant-tunneling devices (with the antisymmetry in the I-V characteristic). Absolute negative conductance can be found from a zero-biased resonant tunneling device when the applied pump power is within a small range. This study verifies the work of Sollner et al. Variable negative conductances at the fundamental and harmonic frequencies can also be obtained from both the unbiased and biased tunnel diodes. The magnitude of the negative conductances can be adjusted by varying the pump amplitude -- a very useful circuit property. However, the voltage range over which the negative conductance occurs moves towards the more positive side of the voltage axis with increasing frequency. Furthermore, the range of the pumping amplitude to obtain negative conductance varies with the parasitics (resistance and capacitance) of the device. The theoretical observation of the dependence of the I-V characteristic of the NDR devices on the power and frequency of the applied pump signal is supported by the experimental results. In addition, novel functions of a NDR device such as self-oscillating frequency multiplier and mixer with gain have been experimentally demonstrated. The unbiased oscillator have also been successfully realized with a NDR device with an antisymmetrical I-V characteristic. Finally, the applications of these device functions will be discussed.

Hwu, R. J.↗