447 results match your criteria Applied Physics Letters[Journal]


Silicon carbide zipper photonic crystal optomechanical cavities.

Appl Phys Lett 2020 Jun 3;116(22):221104. Epub 2020 Jun 3.

Department of Electrical and Computer Engineering, University of Rochester, Rochester, New York 14627, USA.

We demonstrate a silicon carbide (SiC) zipper photonic crystal optomechanical cavity. The device is on a 3C-SiC-on-silicon platform and has a compact footprint of ∼30 × 1 m. The device shows an optical quality of 2800 at telecom and a mechanical quality of 9700 at 12 MHz with an effective mass of ∼3. Read More

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http://dx.doi.org/10.1063/5.0010078DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7272204PMC

Upper limit for angular compounding speckle reduction.

Appl Phys Lett 2019 May 28;114(21):211101. Epub 2019 May 28.

Angular compounding is a technique for reducing speckle noise in optical coherence tomography that is claimed to significantly improve the signal-to-noise ratio (SNR) of images without impairing their spatial resolution. Here, we examine how focal point movements caused by optical aberrations in an angular compounding system may produce unintended spatial averaging and concomitant loss of spatial resolution. Experimentally, we accounted for such aberrations by aligning our system and measuring distortions in images and found that when the distortions were corrected, the speckle reduction by angular compounding was limited. Read More

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http://dx.doi.org/10.1063/1.5088709DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7195867PMC

Perspectives on high resolution microvascular imaging with contrast ultrasound.

Appl Phys Lett 2020 May;116(21):210501

The Joint Department of Biomedical Engineering, The University of North Carolina at Chapel Hill and North Carolina State University, Campus Box 7575, Chapel Hill, North Carolina 27599, USA.

Recent developments in contrast enhanced ultrasound have demonstrated a potential to visualize small blood vessels , unlike anything possible with traditional grayscale ultrasound. This Perspective article introduces microvascular imaging strategies and their underlying technology. Read More

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http://dx.doi.org/10.1063/5.0012283DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7253217PMC

Changes in microbubble dynamics upon adhesion to a solid surface.

Appl Phys Lett 2020 Mar 24;116(12):123703. Epub 2020 Mar 24.

Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, USA.

The interaction between an acoustically driven microbubble and a surface is of interest for a variety of applications, such as ultrasound imaging and therapy. Prior investigations have mainly focused on acoustic effects of a rigid boundary, where it was generally observed that the wall increases inertia and reduces the microbubble resonance frequency. Here we investigate the response of a lipid-coated microbubble adherent to a rigid wall. Read More

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http://dx.doi.org/10.1063/1.5135017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7093207PMC

Super-shear evanescent waves for non-contact elastography of soft tissues.

Appl Phys Lett 2019 Aug 21;115(8):083701. Epub 2019 Aug 21.

Department of Bioengineering, University of Washington, Seattle, Washington 98195, USA.

We describe surface wave propagation in soft elastic media at speeds exceeding the bulk shear wave speed. By linking these waves to the elastodynamic Green's function, we derive a simple relationship to quantify the elasticity of a soft medium from the speed of this supershear evanescent wave (SEW). We experimentally probe SEW propagation in tissue-mimicking phantoms, human cornea , and skin using a high-speed optical coherence elastography system. Read More

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http://dx.doi.org/10.1063/1.5111952DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7043857PMC

Engineering the gain-bandwidth product of phototransistor diodes.

Appl Phys Lett 2019 Jul 30;115(5):051104. Epub 2019 Jul 30.

Bio-Inspired Sensors and Optoelectronics Laboratory, Northwestern University, 2145 Sheridan Rd, Evanston, Illinois 60208, USA.

In recent years, phototransistors have considerably expanded their field of application, including for instance heterodyne detection and optical interconnects. Unlike in low-light imaging, some of these applications require fast photodetectors that can operate in relatively high light levels. Since the gain and bandwidth of phototransistors are not constant across different optical powers, the devices that have been optimized for operation in low light level cannot effectively be employed in different technological applications. Read More

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http://dx.doi.org/10.1063/1.5095815DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7043828PMC

Viscoelastic second normal stress difference dominated multiple-stream particle focusing in microfluidic channels.

Appl Phys Lett 2019 Dec 24;115(26):263702. Epub 2019 Dec 24.

Center of Excellence for Biomedical Microfluidics, Department of Mechanical Engineering, University of Utah, Salt Lake City, Utah 84112, USA.

Particle focusing in viscoelastic fluid flow is a promising approach for inducing particle separations in microfluidic devices. The results from theoretical studies indicated that multiple stream particle focusing can be realized with a large magnitude of the elastic second normal stress difference (N). For dilute polymer solutions, theoretical and experimental studies show that the magnitude of N is never large, no matter how large the polymer molecular weight nor how high the shear rate. Read More

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http://dx.doi.org/10.1063/1.5129281DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7043827PMC
December 2019

Accurate phase retrieval of complex 3D point spread functions with deep residual neural networks.

Appl Phys Lett 2019 Dec 18;115(25):251106. Epub 2019 Dec 18.

Department of Chemistry, Stanford University, Stanford, California 94305, USA.

Phase retrieval, i.e., the reconstruction of phase information from intensity information, is a central problem in many optical systems. Read More

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http://dx.doi.org/10.1063/1.5125252DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7043838PMC
December 2019
3.302 Impact Factor

Laser-driven semiconductor switch for generating nanosecond pulses from a megawatt gyrotron.

Appl Phys Lett 2019 Apr 24;114(16):164102. Epub 2019 Apr 24.

Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.

A laser-driven semiconductor switch (LDSS) employing silicon (Si) and gallium arsenide (GaAs) wafers has been used to produce nanosecond-scale pulses from a 3 s, 110 GHz gyrotron at the megawatt power level. Photoconductivity was induced in the wafers using a 532 nm laser, which produced 6 ns, 230 mJ pulses. Irradiation of a single Si wafer by the laser produced 110 GHz RF pulses with a 9 ns width and >70% reflectance. Read More

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http://dx.doi.org/10.1063/1.5093639DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7043829PMC

Dual-polarization analog optical phase conjugation for focusing light through scattering media.

Appl Phys Lett 2019 Jun 13;114(23):231104. Epub 2019 Jun 13.

Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, Department of Electrical Engineering, California Institute of Technology, Pasadena, California 91125, USA.

Focusing light through or inside scattering media by the analog optical phase conjugation (AOPC) technique based on photorefractive crystals (PRCs) has been intensively investigated due to its high controlled degrees of freedom and short response time. However, the existing AOPC systems only phase-conjugate the scattered light in one polarization direction, while the polarization state of light scattered through a thick scattering medium is spatially random in general, which means that half of the scattering information is lost. Here, we propose dual-polarization AOPC for focusing light through scattering media to improve the efficiency and fidelity in the phase conjugation. Read More

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http://dx.doi.org/10.1063/1.5097181DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6565428PMC
June 2019
3.302 Impact Factor

Numerical modeling of ultrasound heating for the correction of viscous heating artifacts in soft tissue temperature measurements.

Appl Phys Lett 2019 May 21;114(20):203702. Epub 2019 May 21.

Department of Biomedical Engineering, Columbia University, New York, New York 10032, USA.

Measuring temperature during focused ultrasound (FUS) procedures is critical for characterization, calibration, and monitoring to ultimately ensure safety and efficacy. Despite the low cost and the high spatial and temporal resolutions of temperature measurements using thermocouples, the viscous heating (VH) artifact at the thermocouple-tissue interface requires reading corrections for correct thermometric analysis. In this study, a simulation pipeline is proposed to correct the VH artifact arising from temperature measurements using thermocouples in FUS fields. Read More

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http://dx.doi.org/10.1063/1.5091108DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6530881PMC
May 2019
6 Reads

A directional fibre optic ultrasound transmitter based on a reduced graphene oxide and polydimethylsiloxane composite.

Appl Phys Lett 2019 Mar 21;114(11):113505. Epub 2019 Mar 21.

Strongly directional ultrasound sources are desirable for many minimally invasive applications, as they enable high-quality imaging in the presence of positioning uncertainty. All-optical ultrasound is an emerging paradigm that exhibits high frequencies, large bandwidths, and a strong miniaturisation potential. Here, we report the design, modelling, and fabrication of a highly directional fibre-optic ultrasound transmitter that uses a composite of reduced graphene oxide and polydimethylsiloxane as the optical ultrasound generator. Read More

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http://dx.doi.org/10.1063/1.5089750DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6428661PMC
March 2019
1 Read

The effect of luminescent coupling on modulated photocurrent measurements in multijunction solar cells.

Appl Phys Lett 2019 ;115(8)

Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.

Luminescent coupling in multijunction solar cells has a major impact on device response, and its impact on current-voltage and quantum efficiency measurements is well established. However, the role of luminescent coupling in more advanced characterization techniques such as modulated photocurrent spectroscopy is virtually unknown. Here we present measurements of the frequency-dependent photocurrent of a triple junction solar cell with significant coupling between adjacent junctions. Read More

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http://dx.doi.org/10.1063/1.5115014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7067222PMC
January 2019

Electron Reflectometry for Measuring Nanostructures on Opaque Substrates.

Appl Phys Lett 2019 ;115(2)

National Institute of Standards and Technology, Materials Science and Engineering Division, Gaithersburg, MD 20910, United States of America.

Here, we present a method for measuring dimensions of nanostructures using specular reflection of electrons from an electronically opaque surface. Development of this method has been motivated by measurement needs of the semiconductor industry, and it can also be more broadly applicable to any periodic, pseudo-periodic or statistically stationary nanostructures or nanopattern on an opaque substrate. In prior work, it was demonstrated through the presentation of proof of concept experiments and simulated examples that Reflective Small Angle Electron Scattering (RSAES) can meet certain dimensional metrology requirements of the semiconductor industry. Read More

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http://dx.doi.org/10.1063/1.5113489DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7067307PMC
January 2019

Improved contacts to p-type MoS transistors by charge-transfer doping and contact engineering.

Appl Phys Lett 2019 ;115(7)

Physical Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland 20899, USA.

MoS is known to show stubborn n-type behavior due to its intrinsic band structure and Fermi level pinning. Here, we investigate the combined effects of molecular doping and contact engineering on the transport and contact properties of monolayer (ML) MoS devices. Significant p-type (hole-transport) behavior was only observed for chemically doped MoS devices with high work function palladium (Pd) contacts, while MoS devices with low work function metal contacts made from titanium showed ambipolar behavior with electron transport favored even after prolonged p-doping treatment. Read More

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http://dx.doi.org/10.1063/1.5100154DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7047721PMC
January 2019

Probing drug-DNA interactions using super-resolution force spectroscopy.

Appl Phys Lett 2018 Nov 6;113(19):193702. Epub 2018 Nov 6.

Department of Chemistry, University of Houston, Houston, Texas 77204, USA.

Atomic magnetometry and ultrasound, as individual techniques, have been used extensively in various physical, chemical, and biomedical fields. Their combined application, however, has been rare. We report that super-resolution force spectroscopy, which is based on the integration of the two techniques, can find unique biophysical applications in studying drug-DNA interactions. Read More

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http://dx.doi.org/10.1063/1.5045787DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6219894PMC
November 2018
33 Reads

Synthetic Bessel light needle for extended depth-of-field microscopy.

Appl Phys Lett 2018 Oct 2;113(18):181104. Epub 2018 Nov 2.

Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, Department of Electrical Engineering, California Institute of Technology, Pasadena, California 91125, USA.

An ultra-long light needle is highly desired in optical microscopy for its ability to improve the lateral resolution over a large depth of field (DOF). However, its use in image acquisition usually relies on mechanical raster scanning, which compromises between imaging speed and stability and thereby restricts imaging performance. Here, we propose a synthetic Bessel light needle (SBLN) that can be generated and scanned digitally by complex field modulation using a digital micromirror device. Read More

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http://dx.doi.org/10.1063/1.5058163DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6214810PMC
October 2018
3 Reads
3.302 Impact Factor

Capillary assisted deposition of carbon nanotube film for strain sensing.

Appl Phys Lett 2017 Oct 26;111(17):173105. Epub 2017 Oct 26.

Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.

Advances in stretchable electronics offer the possibility of developing skin-like motion sensors. Carbon nanotubes (CNTs), owing to their superior electrical properties, have great potential for applications in such sensors. In this paper, we report a method for deposition and patterning of CNTs on soft, elastic polydimethylsiloxane (PDMS) substrates using capillary action. Read More

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http://aip.scitation.org/doi/10.1063/1.5001754
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http://dx.doi.org/10.1063/1.5001754DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6207349PMC
October 2017
42 Reads

Direct-coupled micro-magnetometer with Y-Ba-Cu-O nano-slit SQUID fabricated with a focused helium ion beam.

Appl Phys Lett 2018 Oct;113(16):162602

Department of Physics, University of California, San Diego, 9500 Gilman Dr., La Jolla, California 92093, USA.

Direct write patterning of high-transition temperature (high-) superconducting oxide thin films with a focused helium ion beam is a formidable approach for the scaling of high- circuit feature sizes down to the nanoscale. In this letter, we report using this technique to create a sensitive micro superconducting quantum interference device (SQUID) magnetometer with a sensing area of about 100 × 100 m. The device is fabricated from a single 35-nm thick YBaCuO film. Read More

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http://aip.scitation.org/doi/10.1063/1.5048776
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http://dx.doi.org/10.1063/1.5048776DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6188902PMC
October 2018
26 Reads

Automated motion-artifact correction in an OCTA image using tensor voting approach.

Appl Phys Lett 2018 Sep 4;113(10):101102. Epub 2018 Sep 4.

Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York 1194-5281, USA.

Optical coherence tomography angiography (OCTA) is a promising tool for imaging subsurface microvascular networks owing to its micron-level resolution and high sensitivity. However, it is not uncommon that OCTA imaging suffers from strip artifacts induced by tissue motion. Although various algorithms for motion correction have been reported, a method that enables motion correction on a single OCTA image remains a challenge. Read More

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http://dx.doi.org/10.1063/1.5036965DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6123061PMC
September 2018
12 Reads

Pulse inversion enhances the passive mapping of microbubble-based ultrasound therapy.

Appl Phys Lett 2018 Jul 24;113(4):044102. Epub 2018 Jul 24.

Department of Biomedical Engineering, Columbia University, New York City, New York 10032, USA.

Therapeutic ultrasound combined with preformed circulating microbubbles has enabled non-invasive and targeted drug delivery into the brain, tumors, and blood clots. Monitoring the microbubble activity is essential for the success of such therapies; however, skull and tissues limit our ability to detect low acoustic signals. Here, we show that by emitting consecutive therapeutic pulses of inverse polarity, the sensitivity in the detection of weak bubble acoustic signals during blood-brain barrier opening is enhanced compared to therapeutic pulses of the same polarity. Read More

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http://aip.scitation.org/doi/10.1063/1.5036516
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http://dx.doi.org/10.1063/1.5036516DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6057789PMC
July 2018
24 Reads

Imaging the three-dimensional orientation and rotational mobility of fluorescent emitters using the Tri-spot point spread function.

Appl Phys Lett 2018 Jul 17;113(3):031103. Epub 2018 Jul 17.

Electrical and Systems Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, USA.

Fluorescence photons emitted by single molecules contain rich information regarding their rotational motions, but adapting single-molecule localization microscopy (SMLM) to measure their orientations and rotational mobilities with high precision remains a challenge. Inspired by dipole radiation patterns, we design and implement a Tri-spot point spread function (PSF) that simultaneously measures the three-dimensional orientation and the rotational mobility of dipole-like emitters across a large field of view. We show that the orientation measurements done using the Tri-spot PSF are sufficiently accurate to correct the anisotropy-based localization bias, from 30 nm to 7 nm, in SMLM. Read More

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http://dx.doi.org/10.1063/1.5031759DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6050162PMC
July 2018
24 Reads

Deep imaging in highly scattering media by combining reflection matrix measurement with Bessel-like beam based optical coherence tomography.

Appl Phys Lett 2018 Jul 3;113(1):011106. Epub 2018 Jul 3.

Beckman Laser Institute, University of California, Irvine, 1002 Health Sciences Road East, Irvine, California 92612, USA.

Multiple scattering in biomedical tissue limits the imaging depth within a range of 1-2 mm for conventional optical imaging techniques. To extend the imaging depth into the scattering medium, a computational method based on the reflection matrix measurement has been developed to retrieve the singly back-scattered signal light from the dominant detrimental multiple-scattered background. After applying singular value decomposition on the measured matrix in the post-process, the target image underneath the turbid media is clearly recovered. Read More

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http://dx.doi.org/10.1063/1.5036661DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6029932PMC
July 2018
5 Reads
3.300 Impact Factor

Strain-induced modulation of near-field radiative transfer.

Appl Phys Lett 2018 Jun 14;112(24):241104. Epub 2018 Jun 14.

Department of Mechanical, Industrial and Systems Engineering, University of Rhode Island, Kingston, Rhode Island 02881, USA.

In this theoretical study, we present a near-field thermal modulator that exhibits change in radiative heat transfer when subjected to mechanical stress/strain. The device has two terminals at different temperatures separated by vacuum: one fixed and one stretchable. The stretchable side contains one-dimensional grating. Read More

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http://dx.doi.org/10.1063/1.5037468DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6002272PMC
June 2018
5 Reads

Brillouin micro-spectroscopy through aberrations via sensorless adaptive optics.

Appl Phys Lett 2018 Apr;112(16):163701

Fischell Department of Bioengineering, University of Maryland, College Park, Maryland 20742, USA.

Brillouin spectroscopy is a powerful optical technique for non-contact viscoelastic characterizations which has recently found applications in three-dimensional mapping of biological samples. Brillouin spectroscopy performances are rapidly degraded by optical aberrations and have therefore been limited to homogenous transparent samples. In this work, we developed an adaptive optics (AO) configuration designed for Brillouin scattering spectroscopy to engineer the incident wavefront and correct for aberrations. Read More

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http://dx.doi.org/10.1063/1.5027838DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5902333PMC
April 2018
2 Reads

Photoacoustic technique to measure temperature effects on microbubble viscoelastic properties.

Appl Phys Lett 2018 Mar 14;112(11):111905. Epub 2018 Mar 14.

Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, USA.

Phospholipid-coated microbubbles are being developed for several biomedical applications, but little is known about the effect of temperature on the viscoelastic properties of the shell. Here, we report on the use of a photoacoustic technique to study the shell properties of individual microbubbles as a function of temperature. The microbubbles were driven into small-amplitude oscillations by ultrasound waves generated from the absorption of an intensity-modulated infrared laser, and these oscillations were detected by forward-light scattering of a second blue laser. Read More

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http://dx.doi.org/10.1063/1.5005548DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5851782PMC
March 2018
2 Reads

Individually grown cobalt nanowires as magnetic force microscopy probes.

Appl Phys Lett 2018 Feb;112(9):092401

Department of Physics, Morgan State University, 1700 East Cold Spring Lane, Baltimore, Maryland 21215, USA.

AC electric fields were utilized in the growth of individual high-aspect ratio cobalt nanowires from simple salt solutions using the Directed Electrochemical Nanowire Assembly method. Nanowire diameters were tuned from the submicron scale to 40 nm by adjusting the AC voltage frequency and the growth solution concentration. The structural properties of the nanowires, including shape and crystallinity, were identified using electron microscopy. Read More

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http://dx.doi.org/10.1063/1.4997310DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5826737PMC
February 2018
41 Reads

Role of temperature and oxygen content on structural and electrical properties of LaBaCoO thin films.

Appl Phys Lett 2018 Feb 15;112(7):073905. Epub 2018 Feb 15.

Department of Materials Design and Innovation, University at Buffalo-the State University of New York, Buffalo, New York 14260, USA.

The role of temperature and the oxygen content in the structural transformation and electrical conductivity of epitaxial double perovskite LaBaCoO (0≤ δ ≤ 1) thin films was systematically investigated. Reciprocal space mapping and ω-2θ x-ray diffraction performed at different temperatures in vacuum indicate that oxygen vacancies in the films become ordered at high temperature in a reducing environment. The changes of the oxygen content and the degree of oxygen vacancy ordering in the films result in a strong in-plane anisotropic lattice deformation and a large thermal expansion coefficient along the c-axis direction. Read More

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http://dx.doi.org/10.1063/1.5009245DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5814307PMC
February 2018
4 Reads

Plasmonic micropillars for precision cell force measurement across a large field-of-view.

Appl Phys Lett 2018 Jan 17;112(3):033701. Epub 2018 Jan 17.

Department of Bioengineering, University of California at Los Angeles (UCLA), Los Angeles, California 90095, USA.

A plasmonic micropillar platform with self-organized gold nanospheres is reported for the precision cell traction force measurement across a large field-of-view (FOV). Gold nanospheres were implanted into the tips of polymer micropillars by annealing gold microdisks with nanosecond laser pulses. Each gold nanosphere is physically anchored in the center of a pillar tip and serves as a strong, point-source-like light scattering center for each micropillar. Read More

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http://dx.doi.org/10.1063/1.5005525DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5771753PMC
January 2018
5 Reads

Microwave SQUID Multiplexer Demonstration for Cosmic Microwave Background Imagers.

Appl Phys Lett 2017 Dec 14;111(24). Epub 2017 Dec 14.

National Institute of Standards and Technology, Boulder, CO 80305, USA.

Key performance characteristics are demonstrated for the microwave SQUID multiplexer (µmux) coupled to transition edge sensor (TES) bolometers that have been optimized for cosmic microwave background (CMB) observations. In a 64-channel demonstration, we show that the µmux produces a white, input referred current noise level of [Formula: see text] at -77 dB microwave probe tone power, which is well below expected fundamental detector and photon noise sources for a ground-based CMB-optimized bolometer. Operated with negligible photon loading, we measure [Formula: see text] in the TES-coupled channels biased at 65% of the sensor normal resistance. Read More

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http://dx.doi.org/10.1063/1.5008527DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5766014PMC
December 2017
1 Read

Approaching the intrinsic quality factor limit for micromechanical bulk acoustic resonators using phononic crystal tethers.

Appl Phys Lett 2017;111(1). Epub 2017 Jul 5.

National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.

We systematically demonstrate that one-dimensional phononic crystal (1-D PnC) tethers can significantly reduce tether loss in micromechanical resonators to a point where the total energy loss is dominated by intrinsic mechanisms, particularly phonon damping. Multiple silicon resonators are designed, fabricated, and tested to provide comparisons in terms of the number of periods in the PnC and the resonance frequency, as well as a comparison with conventional straight-beam tethers. The product of resonance frequency and measured quality factor () is the critical figure of merit, as it is inversely related to the total energy dissipation in a resonator. Read More

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http://dx.doi.org/10.1063/1.4990960DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5749427PMC
July 2017
5 Reads

Revealing the glass transition in shape memory polymers using Brillouin spectroscopy.

Appl Phys Lett 2017 Dec 13;111(24):241904. Epub 2017 Dec 13.

Texas A&M University, 101 Bizzell St., College Station, Texas 77840, USA.

Emerging medical devices which employ shape memory polymers (SMPs) require precise measurements of the glass transition temperature (T) to ensure highly controlled shape recovery kinetics. Conventional techniques like differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) have limitations that prevent utilization for certain devices, including limited accuracy and the need for sacrificial samples. In this report, we employ an approach based on Brillouin spectroscopy to probe the glass transition of SMPs rapidly, remotely, and nondestructively. Read More

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http://dx.doi.org/10.1063/1.4999803DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5729035PMC
December 2017
4 Reads

Photonic-band-gap gyrotron amplifier with picosecond pulses.

Appl Phys Lett 2017 Dec 5;111(23):233504. Epub 2017 Dec 5.

Plasma Science and Fusion Center, Massachusetts Institute of Technology, 77 Mass. Ave., Cambridge, Massachusetts 02139, USA.

We report the amplification of 250 GHz pulses as short as 260 ps without observation of pulse broadening using a photonic-band-gap circuit gyrotron traveling-wave-amplifier. The gyrotron amplifier operates with a device gain of 38 dB and an instantaneous bandwidth of 8 GHz. The operational bandwidth of the amplifier can be tuned over 16 GHz by adjusting the operating voltage of the electron beam and the magnetic field. Read More

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http://dx.doi.org/10.1063/1.5006348DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5718917PMC
December 2017
4 Reads

High-speed single-shot optical focusing through dynamic scattering media with full-phase wavefront shaping.

Appl Phys Lett 2017 Nov 30;111(22):221109. Epub 2017 Nov 30.

Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, Department of Electrical Engineering, California Institute of Technology, Pasadena, California 91125, USA.

In biological applications, optical focusing is limited by the diffusion of light, which prevents focusing at depths greater than ∼1 mm in soft tissue. Wavefront shaping extends the depth by compensating for phase distortions induced by scattering and thus allows for focusing light through biological tissue beyond the optical diffusion limit by using constructive interference. However, due to physiological motion, light scattering in tissue is deterministic only within a brief speckle correlation time. Read More

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http://dx.doi.org/10.1063/1.5009113DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5709093PMC
November 2017
16 Reads

Reflective Small Angle Electron Scattering to Characterize Nanostructures on Opaque Substrates.

Appl Phys Lett 2017 Sep 22;111(12). Epub 2017 Sep 22.

Center of Measurement Science, Industrial Technology Research Institute, Hsinchu 30011, Taiwan.

Features sizes in integrated circuits (ICs) are often at the scale of 10 nm and are ever shrinking. ICs appearing in today's computers and hand held devices are perhaps the most prominent examples. These smaller feature sizes demand equivalent advances in fast and accurate dimensional metrology for both development and manufacturing. Read More

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http://dx.doi.org/10.1063/1.4991696DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5726286PMC
September 2017
3 Reads

Focusing light through scattering media by polarization modulation based generalized digital optical phase conjugation.

Appl Phys Lett 2017 Nov 16;111(20):201108. Epub 2017 Nov 16.

Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, Department of Electrical Engineering, California Institute of Technology, Pasadena, California 91125, USA.

Optical scattering prevents light from being focused through thick biological tissue at depths greater than ∼1 mm. To break this optical diffusion limit, digital optical phase conjugation (DOPC) based wavefront shaping techniques are being actively developed. Previous DOPC systems employed spatial light modulators that modulated either the phase or the amplitude of the conjugate light field. Read More

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http://dx.doi.org/10.1063/1.5005831DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5690666PMC
November 2017
14 Reads
2 Citations
3.302 Impact Factor

Quantitative angle-insensitive flow measurement using relative standard deviation OCT.

Appl Phys Lett 2017 Oct 31;111(18):181101. Epub 2017 Oct 31.

Beckman Laser Institute, University of California, Irvine, Irvine, California 92612, USA.

Incorporating different data processing methods, optical coherence tomography (OCT) has the ability for high-resolution angiography and quantitative flow velocity measurements. However, OCT angiography cannot provide quantitative information of flow velocities, and the velocity measurement based on Doppler OCT requires the determination of Doppler angles, which is a challenge in a complex vascular network. In this study, we report on a relative standard deviation OCT (RSD-OCT) method which provides both vascular network mapping and quantitative information for flow velocities within a wide range of Doppler angles. Read More

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http://dx.doi.org/10.1063/1.5009200DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5663647PMC
October 2017
21 Reads

Ultra-thin metasurface microwave flat lens for broadband applications.

Appl Phys Lett 2017 May 31;110(22):224101. Epub 2017 May 31.

Center for Integrated Nanotechnologies, Los Alamos National Laboratory, MS K771, Los Alamos, New Mexico 87545, USA.

We demonstrate a metasurface-based ultrathin flat lens operating at microwave frequencies. A series of subwavelength metallic split-ring resonators, which are sandwiched between two cross-polarized metallic gratings, are defined to obtain a radially symmetric parabolic phase distribution, covering relative phase differences ranging from 0 to 2.5π radians to create a lens. Read More

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http://dx.doi.org/10.1063/1.4984219DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5648571PMC
May 2017
7 Reads

Emission enhancement through Nd-Yb energy transfer in multifunctional NaGdF nanocrystals.

Appl Phys Lett 2017 May 31;110(22):223107. Epub 2017 May 31.

Department of Physics and Astronomy, The University of Texas at San Antonio, San Antonio, Texas 78249, USA.

The growing need for biomedical contrast agents has led to the current development of multi-functional materials such as lanthanide-based nanoparticles (NPs). The optical and magnetic properties these nanoparticles (NPs) possess are important to enhance current biomedical imaging techniques. To increase the optical emissions of the nanoparticles, neodymium (Nd) and ytterbium (Yb) were introduced into a magnetic host of NaGdF. Read More

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http://dx.doi.org/10.1063/1.4984140DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5552399PMC
May 2017
47 Reads

A capacitive ultrasonic transducer based on parametric resonance.

Appl Phys Lett 2017 Jul;111(4):043503

G. W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.

A capacitive ultrasonic transducer based on a parametric resonator structure is described and experimentally demonstrated. The transducer structure, which we call capacitive parametric ultrasonic transducer (CPUT), uses a parallel plate capacitor with a movable membrane as part of a degenerate parametric series RLC resonator circuit with a resonance frequency of f. When the capacitor plate is driven with an incident harmonic ultrasonic wave at the pump frequency of 2f with sufficient amplitude, the RLC circuit becomes unstable and ultrasonic energy can be efficiently converted to an electrical signal at f frequency in the RLC circuit. Read More

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http://dx.doi.org/10.1063/1.4995564DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5524589PMC
July 2017
3 Reads

Hybrid tandem quantum dot/organic photovoltaic cells with complementary near infrared absorption.

Appl Phys Lett 2017 May 1;110(22):223903. Epub 2017 Jun 1.

King Abdullah University of Science and Technology (KAUST), KAUST Solar Center (KSC), and Physical Science and Engineering Division, Thuwal 23955-6900, Saudi Arabia.

Monolithically integrated hybrid tandem solar cells that effectively combine solution-processed colloidal quantum dot (CQD) and organic bulk heterojunction subcells to achieve tandem performance that surpasses the individual subcell efficiencies have not been demonstrated to date. In this work, we demonstrate hybrid tandem cells with a low bandgap PbS CQD subcell harvesting the visible and near-infrared photons and a polymer:fullerene-poly (diketopyrrolopyrrole-terthiophene) (PDPP3T):[6,6]-phenyl-C-butyric acid methyl ester (PCBM)-top cell absorbing effectively the red and near-infrared photons of the solar spectrum in a complementary fashion. The two subcells are connected in series via an interconnecting layer (ICL) composed of a metal oxide layer, a conjugated polyelectrolyte, and an ultrathin layer of Au. Read More

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http://dx.doi.org/10.1063/1.4984023DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5453788PMC
May 2017
63 Reads

Optical fiber ultrasound transmitter with electrospun carbon nanotube-polymer composite.

Appl Phys Lett 2017 May 1;110(22):223701. Epub 2017 Jun 1.

Department of Electronic and Electrical Engineering, University College London, London WC1E 7JE, United Kingdom.

All-optical ultrasound transducers are promising for imaging applications in minimally invasive surgery. In these devices, ultrasound is transmitted and received through laser modulation, and they can be readily miniaturized using optical fibers for light delivery. Here, we report optical ultrasound transmitters fabricated by electrospinning an absorbing polymer composite directly onto the end-face of optical fibers. Read More

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http://dx.doi.org/10.1063/1.4984838DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5453807PMC
May 2017
20 Reads

High-precision deformation mapping in finFET transistors with two nanometre spatial resolution by precession electron diffraction.

Appl Phys Lett 2017 May 1;110(22):223109. Epub 2017 Jun 1.

IBM Research, 257 Fuller Road, Albany, New York 12203, USA.

Precession electron diffraction has been used to systematically measure the deformation in Si/SiGe blanket films and patterned finFET test structures grown on silicon-on-insulator type wafers. Deformation maps have been obtained with a spatial resolution of 2.0 nm and a precision of ±0. Read More

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http://dx.doi.org/10.1063/1.4983124DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5453792PMC
May 2017
7 Reads

Texture Evolution during Isothermal, Isostrain and Isobaric Loading of Polycrystalline Shape Memory NiTi.

Appl Phys Lett 2017 Jun 23;110(25). Epub 2017 Jun 23.

Advanced Materials Processing and Analysis Center (AMPAC); Materials Science and Engineering Department; Mechanical and Aerospace Engineering Department; University of Central Florida, 12760 Pegasus Drive, Orlando, FL 32816, USA.

neutron diffraction was used to provide insight into martensite variant microstructures during isothermal, isobaric, and isostrain loading in shape memory NiTi. Results show variant microstructures were equivalent for the corresponding strain and more importantly, the reversibility and equivalency was immediately evident in variant microstructures that were first formed isobarically but then reoriented to a near random self-accommodated microstructure following isothermal deformation. Variant microstructures formed isothermally were not significantly affected by a subsequent thermal cycle under constant strain. Read More

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http://dx.doi.org/10.1063/1.4989523DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6288671PMC
June 2017
1 Read

Athermal synchronization of laser source with WDM filter in a silicon photonics platform.

Appl Phys Lett 2017 May;110(21):211105

Research Laboratory of Electronics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.

In an optical interconnect circuit, microring resonators (MRRs) are commonly used in wavelength division multiplexing systems. To make the MRR and laser synchronized, the resonance wavelength of the MRR needs to be thermally controlled, and the power consumption becomes significant with a high-channel count. Here, we demonstrate an athermally synchronized rare-earth-doped laser and MRR. Read More

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http://dx.doi.org/10.1063/1.4984022DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5440232PMC
May 2017
38 Reads

Quantitative measurements of dielectrophoresis in a nanoscale electrode array with an atomic force microscopy.

Appl Phys Lett 2017 May 17;110(20):203701. Epub 2017 May 17.

Department of Physics, North Dakota State University, Fargo, North Dakota 58108, USA.

Nanoelectronic devices integrated with dielectrophoresis (DEP) have been promoted as promising platforms for trapping, separating, and concentrating target biomarkers and cancer cells from a complex medium. Here, we visualized DEP and DEP gradients in conventional nanoelectronic devices by using multi-pass atomic force microcopy techniques. Our measurements directly demonstrated a short range DEP only at sharp step edges of electrodes, frequency dependent DEP polarity, and separation distance dependent DEP strength. Read More

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http://dx.doi.org/10.1063/1.4983785DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5435496PMC
May 2017
4 Reads

Frequency dependence of the coercive field of 0.71Pb(MgNb)O-0.29PbTiO single crystal from 0.01 Hz to 5 MHz.

Appl Phys Lett 2017 May 17;110(20):202904. Epub 2017 May 17.

College of Mathematics, Physics and Information Engineering, Zhejiang Normal University, Jinhua, Zhejiang 321004, China.

The frequency dependence of the coercive field in [001] poled 0.71Pb(MgNb)O-0.29PbTiO single crystals was investigated as a function of frequency from 0. Read More

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http://aip.scitation.org/doi/10.1063/1.4983712
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http://dx.doi.org/10.1063/1.4983712DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5435517PMC
May 2017
10 Reads

Chemical etching of silicon carbide in pure water by using platinum catalyst.

Appl Phys Lett 2017 May;110(20):201601

Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, Osaka 565-0871, Japan.

Chemical etching of SiC was found to proceed in pure water with the assistance of a Pt catalyst. A 4H-SiC (0001) wafer was placed and slid on a polishing pad in pure water, on which a thin Pt film was deposited to give a catalytic nature. Etching of the wafer surface was observed to remove protrusions preferentially by interacting with the Pt film more frequently, thus flattening the surface. Read More

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http://dx.doi.org/10.1063/1.4983206DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5432371PMC
May 2017
9 Reads

Longitudinal shear wave imaging for elasticity mapping using optical coherence elastography.

Appl Phys Lett 2017 May;110(20):201101

Beckman Laser Institute, University of California, Irvine, Irvine, California 92612, USA.

Shear wave measurements for the determination of tissue elastic properties have been used in clinical diagnosis and soft tissue assessment. A shear wave propagates as a transverse wave where vibration is perpendicular to the wave propagation direction. Previous transverse shear wave measurements could detect the shear modulus in the lateral region of the force; however, they could not provide the elastic information in the axial region of the force. Read More

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http://dx.doi.org/10.1063/1.4983292DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5432373PMC
May 2017
19 Reads

Nonlinear ultrasound imaging of nanoscale acoustic biomolecules.

Appl Phys Lett 2017 Feb 17;110(7):073704. Epub 2017 Feb 17.

Division of Chemistry and Chemical Engineering, California Institute of Technology , Pasadena, California 91125, USA.

Ultrasound imaging is widely used to probe the mechanical structure of tissues and visualize blood flow. However, the ability of ultrasound to observe specific molecular and cellular signals is limited. Recently, a unique class of gas-filled protein nanostructures called gas vesicles (GVs) was introduced as nanoscale (∼250 nm) contrast agents for ultrasound, accompanied by the possibilities of genetic engineering, imaging of targets outside the vasculature and monitoring of cellular signals such as gene expression. Read More

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http://dx.doi.org/10.1063/1.4976105DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5315666PMC
February 2017
3 Reads