scholarly journals Three-dimensional cross-nanowire networks recover full terahertz state

Science ◽  
2020 ◽  
Vol 368 (6490) ◽  
pp. 510-513 ◽  
Author(s):  
Kun Peng ◽  
Dimitars Jevtics ◽  
Fanlu Zhang ◽  
Sabrina Sterzl ◽  
Djamshid A. Damry ◽  
...  
Keyword(s):  
Polarization State ◽  
Three Dimensional ◽  
Wide Band ◽  
Field Vector ◽  
Infrared Light ◽  
Electromagnetic Spectrum ◽  
Polarization Component ◽  
Security Screening ◽  
Orthogonal Components ◽  
Nanowire Networks

Terahertz radiation encompasses a wide band of the electromagnetic spectrum, spanning from microwaves to infrared light, and is a particularly powerful tool for both fundamental scientific research and applications such as security screening, communications, quality control, and medical imaging. Considerable information can be conveyed by the full polarization state of terahertz light, yet to date, most time-domain terahertz detectors are sensitive to just one polarization component. Here we demonstrate a nanotechnology-based semiconductor detector using cross-nanowire networks that records the full polarization state of terahertz pulses. The monolithic device allows simultaneous measurements of the orthogonal components of the terahertz electric field vector without cross-talk. Furthermore, we demonstrate the capabilities of the detector for the study of metamaterials.

scholarly journals Giant Magnetoresistance and Magneto-Thermopower in 3D Interconnected NixFe1−x/Cu Multilayered Nanowire Networks

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1133
Author(s):  
Nicolas Marchal ◽  
Tristan da Câmara Santa Clara Gomes ◽  
Flavio Abreu Araujo ◽  
Luc Piraux
Keyword(s):  
Giant Magnetoresistance ◽  
Nanowire Array ◽  
Three Dimensional ◽  
Strong Increase ◽  
Thermoelectric Effect ◽  
Heat Management ◽  
Thermoelectric Effects ◽  
Nanowire Network ◽  
Potential Applications ◽  
Nanowire Networks

The versatility of the template-assisted electrodeposition technique to fabricate complex three-dimensional networks made of interconnected nanowires allows one to easily stack ferromagnetic and non-magnetic metallic layers along the nanowire axis. This leads to the fabrication of unique multilayered nanowire network films showing giant magnetoresistance effect in the current-perpendicular-to-plane configuration that can be reliably measured along the macroscopic in-plane direction of the films. Moreover, the system also enables reliable measurements of the analogous magneto-thermoelectric properties of the multilayered nanowire networks. Here, three-dimensional interconnected NixFe1−x/Cu multilayered nanowire networks (with 0.60≤x≤0.97) are fabricated and characterized, leading to large magnetoresistance and magneto-thermopower ratios up to 17% and −25% in Ni80Fe20/Cu, respectively. A strong contrast is observed between the amplitudes of magnetoresistance and magneto-thermoelectric effects depending on the Ni content of the NiFe alloys. In particular, for the highest Ni concentrations, a strong increase in the magneto-thermoelectric effect is observed, more than a factor of 7 larger than the magnetoresistive effect for Ni97Fe3/Cu multilayers. This sharp increase is mainly due to an increase in the spin-dependent Seebeck coefficient from −7 µV/K for the Ni60Fe40/Cu and Ni70Fe30/Cu nanowire arrays to −21 µV/K for the Ni97Fe3/Cu nanowire array. The enhancement of the magneto-thermoelectric effect for multilayered nanowire networks based on dilute Ni alloys is promising for obtaining a flexible magnetic switch for thermoelectric generation for potential applications in heat management or logic devices using thermal energy.

scholarly journals Properties of spoof plasmon in thin structures

2018 ◽  
Vol 474 (2220) ◽  
pp. 20180205
Author(s):  
Soumitra Roy Joy ◽  
Hao Yu ◽  
Pinaki Mazumder
Keyword(s):  
Three Dimensional ◽  
Wide Band ◽  
Blue Shift ◽  
Plasmon Mode ◽  
Dimensional Structure ◽  
Thin Structures ◽  
Enhanced Sensitivity ◽  
Optical Modes ◽  
Specific Frequency ◽  
Modulation Rate

Spoof surface plasmon polariton (SSPP) is an exotic electromagnetic state that confines light at a subwavelength scale at a design-specific frequency. It has been known for a while that spoof plasmon mode can exist in planar, thin structures with dispersion properties similar to that of its wide three-dimensional structure counterpart. We, however, have shown that spoof plasmons in thin structures possess some unique properties that remain unexplored. Our analysis reveals that the field interior to SSPP waveguide can achieve an exceptional hyperbolic spatial dependence, which can explain why spoof plasma resonance incurs red-shift with the reduction of the waveguide thickness, whereas common wisdom suggests frequency blue-shift of a resonant structure with its size reduction. In addition, we show that strong confinement can be achieved over a wide band in thin spoof plasmon structure, ranging from the spoof plasma frequency up to a lower frequency considerably away from the resonant point. The nature of lateral confinement in thin SSPP structures may enable interesting applications involving fast modulation rate due to enhanced sensitivity of optical modes without compromising modal confinement.

End-Wall Film Cooling Through Fan-Shaped Holes With Different Area Ratios

2006 ◽  
Vol 129 (2) ◽  
pp. 212-220 ◽  
Author(s):  
Giovanna Barigozzi ◽  
Giuseppe Franchini ◽  
Antonio Perdichizzi
Keyword(s):  
Secondary Flow ◽  
Mass Flow ◽  
Film Cooling ◽  
Three Dimensional ◽  
Wide Band ◽  
Lateral Spreading ◽  
Area Ratio ◽  
Adiabatic Effectiveness ◽  
Flow Effects ◽  
End Wall

The present paper reports on the aerothermal performance of a nozzle vane cascade, with film-cooled end walls. The coolant is injected through four rows of cylindrical holes with conical expanded exits. Two end-wall geometries with different area ratios have been compared. Tests have been carried out at low speed (M=0.2), with coolant to mainstream mass flow ratio varied in the range 0.5–2.5%. Secondary flow assessment has been performed through three-dimensional (3D) aerodynamic measurements, by means of a miniaturized five-hole probe. Adiabatic effectiveness distributions have been determined by using the wide-band thermochromic liquid crystals technique. For both configurations and for all the blowing conditions, the coolant share among the four rows has been determined. The aerothermal performances of the cooled vane have been analyzed on the basis of secondary flow effects and laterally averaged effectiveness distributions; this analysis was carried out for different coolant mass flow ratios. It was found that the smaller area ratio provides better results in terms of 3D losses and secondary flow effects; the reason is that the higher momentum of the coolant flow is going to better reduce the secondary flow development. The increase of the fan-shaped hole area ratio gives rise to a better coolant lateral spreading, but appreciable improvements of the adiabatic effectiveness were detected only in some regions and for large injection rates.

A Technique for Quantitative Assessment of Three-Dimensional Motion with Applications to Human Joints

1989 ◽  
Vol 203 (4) ◽  
pp. 207-213 ◽  
Author(s):  
N P Reddy ◽  
M J Askew ◽  
F M Baniewicz ◽  
A Melby ◽  
K A Fuller ◽  
...  
Keyword(s):  
Quantitative Assessment ◽  
Quantitative Measurement ◽  
Three Dimensional ◽  
The Other ◽  
Coordinate Frames ◽  
Orthogonal Components ◽  
Human Joints ◽  
Spatial Locations

A technique is developed for quantitative measurement of general three-dimensional motion, and this technique is applied to the kinematics of anatomical joints. The spatial locations of three orthogonal points representing coordinate frames on each member of the joint are measured during motion of the joint by photo encoders of a three-dimensional mechanical pointer. Kinematic calculations are used to derive, from the experimentally collected data, the six orthogonal components of the motion of one member relative to the other. The accuracy of this technique is presented. Applications to the knee and ankle are discussed.

scholarly journals Three-Dimensional Live Imaging of Bovine Preimplantation Embryos: A New Method for IVF Embryo Evaluation

2021 ◽  
Vol 8 ◽  
Author(s):  
Yasumitsu Masuda ◽  
Ryo Hasebe ◽  
Yasushi Kuromi ◽  
Masayoshi Kobayashi ◽  
Kanako Urataki ◽  
...  
Keyword(s):  
Embryo Transfer ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Three Dimensional ◽  
Preimplantation Embryos ◽  
Infrared Light ◽  
Bovine Embryo ◽  
Bovine Embryos ◽  
Cell Stage ◽  
Developmental Potential

Conception rates for transferred bovine embryos are lower than those for artificial insemination. Embryo transfer (ET) is widely used in cattle but many of the transferred embryos fail to develop, thus, a more effective method for selecting bovine embryos suitable for ET is required. To evaluate the developmental potential of bovine preimplantation embryos (2-cell stage embryos and blastocysts), we have used the non-invasive method of optical coherence tomography (OCT) to obtain live images. The images were used to evaluate 22 parameters of blastocysts, such as the volume of the inner cell mass and the thicknesses of the trophectoderm (TE). Bovine embryos were obtained by in vitro fertilization (IVF) of the cumulus-oocyte complexes aspirated by ovum pick-up from Japanese Black cattle. The quality of the blastocysts was examined under an inverted microscope and all were confirmed to be Code1 according to the International Embryo Transfer Society standards for embryo evaluation. The OCT images of embryos were taken at the 2-cell and blastocyst stages prior to the transfer. In OCT, the embryos were irradiated with near-infrared light for a few minutes to capture three-dimensional images. Nuclei of the 2-cell stage embryos were clearly observed by OCT, and polynuclear cells at the 2-cell stage were also clearly found. With OCT, we were able to observe embryos at the blastocyst stage and evaluate their parameters. The conception rate following OCT (15/30; 50%) is typical for ETs and no newborn calves showed neonatal overgrowth or died, indicating that the OCT did not adversely affect the ET. A principal components analysis was unable to identify the parameters associated with successful pregnancy, while by using hierarchical clustering analysis, TE volume has been suggested to be one of the parameters for the evaluation of bovine embryo. The present results show that OCT imaging can be used to investigate time-dependent changes of IVF embryos. With further improvements, it should be useful for selecting high-quality embryos for transfer.

Size Effect in Germanium Nanostructures Fabricated by Pulsed Laser Deposition

1999 ◽  
Vol 581 ◽  
Author(s):  
K.M. Hassan ◽  
A.K. Sharma ◽  
J. Narayan ◽  
J.F. Muth ◽  
C.W. Teng ◽  
...  
Keyword(s):  
Pulsed Laser Deposition ◽  
Band Gap ◽  
Quantum Confinement ◽  
Three Dimensional ◽  
Pulsed Laser ◽  
Wide Band ◽  
Laser Deposition ◽  
Island Growth ◽  
Wide Band Gap ◽  
Average Size

ABSTRACTWe have fabricated Ge nanostructures buried in AlN and Al2O3 matrices grown on Si(111) and sapphire substrates by pulsed laser deposition. Our approach involved three-dimensional island growth of low band-gap material followed by a layer of wide band-gap material. The nanodots were uniformly distributed in between alternating layers of AlN or Al2O3. It was observed that these nanodots exhibit crystalline structure when grown at 300-500 °C. The average size of Ge islands was determined to be ∼5-15 nm, which could be varied by controlling laser deposition and substrate parameters. The Raman spectrum showed a peak of the Ge-Ge vibrational mode downward shifted upto 295 cm− which is caused by quantum confinement of phonons in the Ge-dots. The photoluminescence of the Ge dots (size ∼15nm) was blue shifted by ∼0.266 eV from the bulk Ge value of 0.73 eV at 77 K, resulting in a distinct peak at ∼1.0 eV. The spectral positions of both E1 and E2 transitions in the absorption spectra at room temperature and 77K shift toward higher energy as the Ge dot size decreases. The interpretation of these behaviors in terms of quantum confinement is discussed in this work, and the importance of pulsed laser deposition in fabricating novel nanostructures is emphasized

Optics, Optical Methods, and Microscopy

2021 ◽  
pp. 345-407
Author(s):  
Kannan M. Krishnan
Keyword(s):  
Optical Microscopy ◽  
Polarization State ◽  
Three Dimensional ◽  
Polarized Light ◽  
Dark Field ◽  
Optical Methods ◽  
Transverse Waves ◽  
Dark Field Imaging ◽  
Propagation Of Light ◽  
Scanning Optical Microscopy

Propagation of light is described as the simple harmonic motion of transverse waves. Combining waves that propagate on orthogonal planes give rise to linear, elliptical, or spherical polarization, depending on their amplitudes and phase differences. Classical experiments of Huygens and Young demonstrated the principle of optical interference and diffraction. Generalization of Fraunhofer diffraction to scattering by a three-dimensional arrangement of atoms in crystals forms the basis of diffraction methods. Fresnel diffraction finds application in the design of zone plates for X-ray microscopy. Optical microscopy, with resolution given by the Rayleigh criterion to be approximately half the wavelength, works best when tailored to the optimal characteristics of the human eye (λ = 550 nm). Lenses suffer from spherical and chromatic aberrations, and astigmatism. Optical microscopes operate in bright-field, oblique, and dark-field imaging conditions, produce interference contrast, and can image with polarized light. Variants include confocal scanning optical microscopy (CSOM). Metallography, widely used to characterize microstructures, requires polished or chemically etched surfaces to provide optimal contrast. Finally, the polarization state of light reflected from the surface of a specimen is utilized in ellipsometry to obtain details of the optical properties and thickness of thin film materials.

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