skip to main content

Title: Three-dimensional imaging from single-element holographic data

We present a holographic imaging approach for the case in which a single source-detector pair is used to scan a sample. The source-detector pair collects intensity-only data at different frequencies and positions. By using an appropriate illumination strategy, we recover field cross correlations over different frequencies for each scan location. The problem is that these field cross correlations are asynchronized, so they have to be aligned first in order to image coherently. This is the main result of the paper: a simple algorithm to synchronize field cross correlations at different locations. Thus, one can recover full field data up to a global phase that is common to all scan locations. The recovered data are, then, coherent over space and frequency so they can be used to form high-resolution three-dimensional images. Imaging with intensity-only data is therefore as good as coherent imaging with full data. In addition, we use anℓ<#comment/>1-norm minimization algorithm that promotes the low dimensional structure of the images, allowing for deep high-resolution imaging.

more » « less
Award ID(s):
Author(s) / Creator(s):
; ; ;
Publisher / Repository:
Optical Society of America
Date Published:
Journal Name:
Journal of the Optical Society of America A
1084-7529; JOAOD6
Page Range / eLocation ID:
Article No. A1
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Electro-optic quantum coherent interfaces map the amplitude and phase of a quantum signal directly to the phase or intensity of a probe beam. At terahertz frequencies, a fundamental challenge is not only to sense such weak signals (due to a weak coupling with a probe in the near-infrared) but also to resolve them in the time domain. Cavity confinement of both light fields can increase the interaction and achieve strong coupling. Using this approach, current realizations are limited to low microwave frequencies. Alternatively, in bulk crystals, electro-optic sampling was shown to reach quantum-level sensitivity of terahertz waves. Yet, the coupling strength was extremely weak. Here, we propose an on-chip architecture that concomitantly provides subcycle temporal resolution and an extreme sensitivity to sense terahertz intracavity fields below 20 V/m. We use guided femtosecond pulses in the near-infrared and a confinement of the terahertz wave to a volume ofVTHz∼<#comment/>10−<#comment/>9(λ<#comment/>THz/2)3in combination with ultraperformant organic molecules (r33=170pm/V) and accomplish a record-high single-photon electro-optic coupling rate ofgeo=2π<#comment/>×<#comment/>0.043GHz, 10,000 times higher than in recent reports of sensing vacuum field fluctuations in bulk media. Via homodyne detection implemented directly on chip, the interaction results into an intensity modulation of the femtosecond pulses. The single-photon cooperativity isC0=1.6×<#comment/>10−<#comment/>8, and the multiphoton cooperativity isC=0.002at room temperature. We show><#comment/>70dBdynamic range in intensity at 500 ms integration under irradiation with a weak coherent terahertz field. Similar devices could be employed in future measurements of quantum states in the terahertz at the standard quantum limit, or for entanglement of subsystems on subcycle temporal scales, such as terahertz and near-infrared quantum bits.

    more » « less
  2. Abstract

    Kondo insulators are expected to transform into metals under a sufficiently strong magnetic field. The closure of the insulating gap stems from the coupling of a magnetic field to the electron spin, yet the required strength of the magnetic field–typically of order 100 T–means that very little is known about this insulator-metal transition. Here we show that Ce$${}_{3}$$3Bi$${}_{4}$$4Pd$${}_{3}$$3, owing to its fortuitously small gap, provides an ideal Kondo insulator for this investigation. A metallic Fermi liquid state is established above a critical magnetic field of only$${B}_{{\rm{c}}}\approx$$Bc11 T. A peak in the strength of electronic correlations near$${B}_{{\rm{c}}}$$Bc, which is evident in transport and susceptibility measurements, suggests that Ce$${}_{3}$$3Bi$${}_{4}$$4Pd$${}_{3}$$3may exhibit quantum criticality analogous to that reported in Kondo insulators under pressure. Metamagnetism and the breakdown of the Kondo coupling are also discussed.

    more » « less
  3. Temperature scaling of collisional broadening parameters for krypton (absorber)4p6S01→<#comment/>5p[3/2]2electronic transition centered at 107.3 nm in the presence of major combustion species (perturber) is investigated. The absorption spectrum in the vicinity of the transition is obtained from the fluorescence due to the two-photon excitation scan of krypton. Krypton was added in small amounts to major combustion species such asCH4,CO2,N2, and air, which then heated to elevated temperatures when flowed through a set of heated coils. In a separate experimental campaign, laminar premixed flat flame product mixtures of methane combustion were employed to extend the investigations to higher temperature ranges relevant to combustion. Collisional full width half maximum (FWHM) (wC) and shift (δ<#comment/>C) were computed from the absorption spectrum by synthetically fitting Voigt profiles to the excitation scans, and their corresponding temperature scaling was determined by fitting power-law temperature dependencies to thewCandδ<#comment/>Cdata for each perturber species. The temperature exponents ofwCandδ<#comment/>Cfor all considered combustion species (perturbers) were−<#comment/>0.73and−<#comment/>0.6, respectively. Whereas the temperature exponents ofwCare closer to the value (−<#comment/>0.7) predicted by the dispersive interaction collision theory, the corresponding exponents ofδ<#comment/>Care in between the dispersive interaction theory and the kinetic theory of hard-sphere collisions. Comparison with existing literature on broadening parameters of NO, OH, and CO laser-induced fluorescence spectra reveal interesting contributions from non-dispersive interactions on the temperature exponent.

    more » « less
  4. Abstract

    Initially, vanadium dioxide seems to be an ideal first-order phase transition case study due to its deceptively simple structure and composition, but upon closer inspection there are nuances to the driving mechanism of the metal-insulator transition (MIT) that are still unexplained. In this study, a local structure analysis across a bulk powder tungsten-substitution series is utilized to tease out the nuances of this first-order phase transition. A comparison of the average structure to the local structure using synchrotron x-ray diffraction and total scattering pair-distribution function methods, respectively, is discussed as well as comparison to bright field transmission electron microscopy imaging through a similar temperature-series as the local structure characterization. Extended x-ray absorption fine structure fitting of thin film data across the substitution-series is also presented and compared to bulk. Machine learning technique, non-negative matrix factorization, is applied to analyze the total scattering data. The bulk MIT is probed through magnetic susceptibility as well as differential scanning calorimetry. The findings indicate the local transition temperature ($$T_c$$Tc) is less than the average$$T_c$$Tcsupporting the Peierls-Mott MIT mechanism, and demonstrate that in bulk powder and thin-films, increasing tungsten-substitution instigates local V-oxidation through the phase pathway VO$$_2\, \rightarrow$$2V$$_6$$6O$$_{13} \, \rightarrow$$13V$$_2$$2O$$_5$$5.

    more » « less
  5. Pressure scaling of collisional broadening parameters of krypton (absorber)4p6S01→<#comment/>→<#comment/>5p[3/2]2transition centered at 107.3 nm in the presence of nitrogenN2(perturber) is investigated. The absorption spectrum in the vicinity of the transition is obtained from the two-photon excitation scan of krypton in the presence of the perturber at different prescribed pressures varying from a few torrs to 10 atm. The absorption spectra reveal noticeable asymmetry at atmospheric pressure, and the asymmetry becomes increasingly pronounced with pressure; however, the absorption spectra at sub-atmospheric pressures tested are symmetric. The absorption spectra are fitted with synthetic asymmetric Voigt profiles across all pressures, wherein the asymmetry parameter is varied to capture the asymmetry at different pressures. The collisional shift (δ<#comment/>C), the symmetric equivalent collisional full width at half maximum (wC,0), and the asymmetry parameter (a) are determined from the synthetic fits at various pressures. All the parameters are observed to vary linearly with pressure over the entire range of the pressure values tested. The mechanisms that cause the asymmetry in the absorption spectra are also discussed.

    more » « less