bluuebunny/crossref_metadata_2025 huggingface dataset:
A Theoretical Study of Nonlinear Multi-Channel Graphene Components for the Near and Far-Infrared
Authors: Christopoulos Thomas , Tsilipakos Odysseas , Ataloglou Vasileios G. , Kriezis Emmanouil E.
Published: January 2021

Two graphene-based nonlinear multi-channel components are presented. They include a graphene-enhanced silicon disk resonator for all-optical saturable-absorption-induced routing in the NIR together with a high conversion-efficiency graphene standing-wave micro-ribbon resonator for FWM in the FIR.
Sensibility approximation for Bragg gratings structures: An interesting tool for sensing design
Authors: Peyton R , Valdiviezo J H Martnez , Videla F , Torchia G A
Published: January 2021

In this work, we present an approach that provides a fast design method for sensing applications. A linear approximation for the sensibility of Bragg grating structures is described and verified.
Semi-Analytical Effective Layer Model for the Skin in the SWIR Spectral Range
Authors: Salem Abdelrahman M. , Othman Ahmed M. , Sabry Yasser M. , Khalil Diaa A. M.
Published: January 2021

A semi-analytical method for calculating an effective model for skin is proposed showing an error less than 10%. The model can be used to study applications such as glucose and alcohol detection efficiently.
Use of FFT to Increase Measurement Range of a Curvature Sensor Based on a Mach-Zehnder Interferometer
Authors: Marrujo-García S. , Hernández-Romano I. , Torres-Cisneros M. , May-Arrioja D. A. , Minkovich Vladimir P. , Monzón-Hernández D.
Published: January 2021

The output signal of Mach-Zehnder curvature sensor was Fourier transformed to increase its curvature range to high value of 1.69 m-1, relative to the traditional fringe contrast measurement 1.09 m-1.
Optical Polarization Rotation through Spin-Photon Entanglement in a Charged Quantum Dot-Micropillar System
Authors: Koleva M. , Maier O. , Haider M. , Jirauschek C. , Müller K. , Slavcheva G.
Published: January 2021

We calculate the spin-induced optical polarisation rotation of a resonant ul-trashort pulse in intermediate and strongly-coupled dot-micropillar systems, showing good agreement with recent experiments and demonstrating onset of Rabi splitting of the cavity mode.
Optical Properties of Finite Subsets of FIB-Milled 2D Periodic Arrays of Gold Nanoplatelets with Sub-20-nm Gaps
Authors: Kashif Muhammad Fayyaz , Pisano Filippo , Balena Antonio , Pisanello Marco , de Marzo Gaia , Algieri Luciana , Qualtieri Antonio , Sileo Leonardo , Stomeo Tiziana , D’Orazio Antonella , De Vittorio Massimo , Pisanello Ferruccio , Grande Marco
Published: January 2021

We theoretically and experimentally investigate the optical properties arising from the illumination of a subset of elements in FIB-milled 2D-periodic arrays of gold nanoplatelets with sub-20-nm gaps.
Low cost coating of high refractive index multilayer TiO2 film for improved photonic applications
Authors: Lodh Soham , Chakraborty Rajib
Published: January 2021

Sol-gel spin coated multilayer high refractive index TiO2 film developed on glass substrate. The refractive index and band-gap can be altered by change the number of deposited layers.
Reflection-suppressed color filter metasurface optimized by particle swarm method
Authors: Hong Jongwoo , Kim Changhyun , Lee Byoungho
Published: January 2021

Conventional transmission-type color filter metasurfaces have not considered reflection that might cause image quality degradation of practical CMOS image sensors including flare effect. Here, we propose RGB color-optimized tapered hyperbolic metamaterial cavities as absorptive color filters. Since multiple geometry parameters need to be considered for optimization, we design our metasurfaces based on particle swarm optimization through FDTD simulations. Consequently, less than 20 % reflection is achieved over visible wavelength and transmission from each RGB-pixel covers about 78% of sRGB region.
Active near-unity absorption resonances in phase-transition material based all-dielectric nanogratings
Authors: Kim Kyuho , Kim Sun-Je , Lee Byoungho
Published: January 2021

We propose and analyze actively tunable near-unity absorption resonances in simple all-dielectric nanogratings based on phase-transition material, vanadium dioxide (VO2), theoretically and numerically. We focus on enhancement and tunability of resonance spectra according to coating of a dielectric transparent optical film on the VO2 nanogratings.
Entanglement Duality Assisted Secure Key Distribution
Authors: Biswas Ayan , Lal Nijil , Banerji Anindya , Singh R. P.
Published: January 2021

Duality of entanglement, a property of quantum indistinguishable particles, manifests that entanglement in only one variable can be revealed at a time. The concept is used to demonstrate a device independent quantum key distribution protocol.
Estimation of cell volume determination accuracy using digital holographic tomography and microscopy
Authors: Belashov A.V. , Gorbenko D.A. , Zhikhoreva A.A. , Belyaeva T.N. , Kornilova E.S. , Semenova I.V. , Vasyutinskii O.S.
Published: January 2021

Digital holographic microscopy and tomography can be successfully used for investigation of optical and morphological parameters of living cells. In this contribution we estimate the determination accuracy of cells volume using these approaches. Data on cells volume obtained using digital holographic microscopy and tomography was validated by comparison with those obtained using confocal fluorescence microscopy.
A simulation study for characterization of the nanoparticles by exploiting optoacoustic effect
Authors: Kaushik Anuj , Prakash Ravi , Warbal Pankaj
Published: January 2021

The Green’s function approach has been utilized in calculating the amplitude of photoacoustic field for various simple and complex nanoparticle shapes. Each particle represents a unique spectrum corresponding to its structure.
Digital Photonic Half Subtractor
Authors: Uddin M. Rakib , Law F. K. , Hamid Zainidi
Published: January 2021

Microring resonator based digital photonic half subtractor is presented. The data transmission rate of 1Gbps and time window of 10ns have been carried out to demonstrate the operation of the proposed design.
Eye3DVas: three-dimensional reconstruction of retinal vascular structures by integrating fundus image features
Authors: Yao Zhaomin , He Kunlin , Zhou Huahui , Zhang Zhenyu , Zhu Gancheng , Xing Chencong , Zhang Jianyuan , Zhang Zhiruo , Shao Bowen , Tao Yang , Sun Xiaohan , Hou Yilin , Duan Meiyu , Liu Shuai , Huang Lan , Zhou Fengfeng
Published: January 2021

Two-dimensional images of fundus blood vessels are easy to obtain with low diagnostic accuracy. This study realized the reconstruction of three-dimensional vascular structures from two-dimensional fundus images to improve the accuracy to 95%.
Structural characterisation of North-east Indian rice starch using Second Harmonic Generation (SHG) microscopy
Authors: Chakraborty Ishita , Govindaraju Indira , Zhuo Guan-Yu , Baruah Vishwa Jyoti , Sarmah Bhaswati , Mahato K. K. , Banik Soumyabrata , Mazumder Nirmal
Published: January 2021

Ultrastructural characterisation of North east Indian rice starch varieties using SHG microscopy. The SHG signal is generated from the amylopectin molecules in rice starch and is further correlated with results obtained from X- ray diffraction.
Compact waveguide-type optical-see-through varifocal near-eye display using focus-tunable lens
Authors: Choi Myeong-Ho , Min Dabin , Park Jae-Hyeung
Published: January 2021

We propose a concept of waveguide-type optical-see-through near-eye display which can generate multiple display planes. Compact formfactor has been achieved thanks to the focus-tunable lens and volume grating couplers with the optical power.
Effect of external focusing conditions on the acoustic and optical emissions from femtosecond laser filaments
Authors: Nalam Samuel Anurag , Elle Manikanta , Harsha S. Sree , Kiran P. Prem
Published: January 2021

The effect of external focusing conditions on the on-axis plasma electron density generated by the fs laser filament in air via corroborated acoustic and optical spectral emission profile measurements is presented.
All-optical logic gates based on FWM in a symmetric hybrid plasmonic silicon waveguide
Authors: Wu Wei , Sun Qibing , Zhao Wei
Published: January 2021

We propose a symmetric hybrid plasmonic silicon waveguide (SHPWG), which could offer broadband flattened dispersion and high nonlinearity. All-optical logic XOR gates for 100 Gb/s signals is realized via four-wave mixing (FWM) in the C-band.
k-Wave simulation study for the characterization of nanoparticles using optoacoustic effect
Authors: Kaushik Anuj , Prakash Ravi , Warbal Pankaj
Published: January 2021

The k-Wave toolbox is utilized for computing the amplitude of the optoacoustic field for gold, silver, and palladium nanoparticles of various shapes. Each particle represents a unique spectrum corresponding to its shape and metal type.
Computing Band Structures of Randomly-Generated 2D Photonic Crystals with Extreme Learning Machines
Authors: Ferreira Adriano da Silva , Malheiros-Silveira Gilliard Nardel , Hernández-Figueroa Hugo Enrique
Published: January 2021

We designed Extreme Learning Machines (ELM) for calculating band structures (BST) of randomly-generated bi-dimensional (2D) photonic crystals and demonstrated fast-training ELM models able to perform fast and accurate BST computations.
Glioma Tumors Classified using Visible Resonance Raman Spectroscopy and Machine Learning
Authors: Wu Binlin , Zhou Yan , Zhang Liang , Zhang Shengjia , Yu Xinguang , Wang Eric , Zhu Ke , Liu Cheng-hui , Alfano Robert R
Published: January 2021

Machine learning algorithms were used to classify and analyze spectral data collected by visible resonance Raman spectroscopy to distinguish normal human brain tissue and glioma tumor tissues at different grades and show promising results.
Numerical Evaluation of Ponderomotive Entanglement in Realistic Experimental Conditions
Authors: Dixon Kahlil Y. , Cohen Lior , Bhusal Narayan , Wipf Christopher , Dowling Jonathan P. , Corbitt Thomas
Published: January 2021

Utilizing the logarithmic negativity (E
N
) entanglement measure, we present an analysis of (optomechanical) ponderomotive entanglement generation. Results predict a max E
N
of about 0.2 and are highly dependent on temperature, loss, and measurement precision.
High pulse energy, femtosecond fiber laser for two-photon imaging
Authors: Turnali Ahmet , Xu Shutao , Sander Michelle Y.
Published: January 2021

We demonstrate an all-fiber thulium-doped laser system that can generate 105-nJ pulses with a repetition rate of 21 MHz at 1890nm. The amplified pulses can be compressed to a pulse duration of 280 fs.
Shack-Hartmann test using micro-holes for testing a concave optical surface
Authors: Núñez Alberto Jaramillo , Juárez Efrén Santamaría , Rodríguez Alejandro Cornejo
Published: January 2021

In this paper will be presented experimental results for testing concave optical surfaces, by means of the Shack-Hartmann test, where a set of micro-holes are used instead of lenses in the construction of the Shack-Hartmann plate.
Tracking Dual Image Transmission through Dispersive Chiral Thick Lens under Dielictric Losses using Fresnel Coefficients
Authors: Salaheddeen G.Bugoffa , Chatterjee Monish R.
Published: January 2021

Fresnel coefficients are used to track dual image formation for electromagnetic propagation from a 2D object through a chiral thick lens with dielectric losses, and real and virtual imaging conditions investigated based on dispersive material parameters.
Generating-function approach for double freeform lens design
Authors: Romijn L. B. , Anthonissen M. J. H. , ten Thije Boonkkamp J. H. M. , IJzerman W. L.
Published: January 2021

Many LED lighting applications involve the design of multiple optical surfaces. A prime example is a single lens with two refractive surfaces. In this paper, we consider an LED light source approximated as a point and a far-field target intensity. Using Hamilton’s characteristic functions, the design problem is converted into two generalized Monge–Ampère equations by deriving a generating function for each optical surface. The generating function is a generalization of the cost function in optimal transport theory. The generalized Monge–Ampère equations are solved using an iterative least-squares algorithm. To compute the first optical surface, we choose an intermediate far-field target intensity. By choosing different intermediate target intensities based on the source and target intensity, we develop a “knob” to distribute the refractive power over both surfaces of the lens. We apply the algorithm on two example problems and show it is capable of producing complicated target distributions.
Cherenkov radiation from a dielectric ball with a channel
Authors: Tyukhtin Andrey V. , Galyamin Sergey N. , Vorobev Viktor V.
Published: January 2021

Radiation of charged particles moving in the presence of dielectric targets is of essential importance for various applications in accelerator and beam physics. As a rule, the sizes of these targets are much larger than the wavelengths under consideration. This fact gives an obvious small parameter of the problem and allows developing approximate methods for analysis. Here we apply one such method (called the “aperture method” in our preceding papers) to analysis of Cherenkov radiation from a charge flying through a vacuum channel in a dielectric sphere. We present analytical results and describe the main physical effects. Typical angular and radial distributions of the radiation field are also presented. In particular, it is shown that the field has an expressed maximum at a certain distance from the sphere. Special attention is paid to the far-field area where the radiation is formed, and corresponding angular distribution does not depend on the distance from the sphere.
Wave packet shaping for a single-photon source
Authors: Ahmadian Azadeh , Malekfar Rasoul
Published: January 2021

For the realization of a quantum network and efficient transfer of information between its nodes, many challenges should be resolved. One of these challenges is related to controlling photons, in that receiving and resending data in a real-time process should be reliable. The uncontrollable and time asymmetry shape of the photon wave packets emitted by quantum sources creates obstacles for reliable information transfer. In this work, an approach has been introduced to tune the wave packet shape of a single photon as a significant factor for absorbing and resending the same information. Since the wave packet of the photon emitted from spontaneous emission cannot be handled, in this research for the wave packet shaping, two lasers with a phase difference between them are proposed, where Rabi frequency

Ω
(
t
)

is considered as a time-dependent function. Studying the temporal evolution of the system states and using the experimental parameters of a real single photon are two steps employed in this paper to achieve the desired outcome. Furthermore, the fidelity of two distant nodes, between which information is transmitted by the proposed single photon, is examined.
Starting dynamics of a linear-cavity femtosecond Mamyshev oscillator
Authors: Chen Yi-Hao , Sidorenko Pavel , Thorne Robert , Wise Frank
Published: January 2021

Mamyshev oscillators can generate high-power femtosecond pulses, but
starting a mode-locked state has remained a major challenge due to the
suppression of continuous-wave lasing. Here, we study the starting
dynamics of a linear Mamyshev oscillator designed to generate
high-power femtosecond pulses while avoiding component damage.
Reliable starting to stable mode-locking is achieved with a
combination of modulation of the pump power and shifting of a filter
passband. The starting process is automated, with full electronic
control. The laser delivers 21-nJ pulses that are dechirped to 65 fs
in duration outside the cavity.
Quantum-Correlated Photon-Pair Generation via Cascaded Nonlinearity in a Thin-Film Lithium-Niobate Waveguide
Authors: Elkus Bradley S. , Abdelsalam Kamal , Fathpour Sasan , Kumar Prem , Kanter Gregory S.
Published: January 2021

We generate quantum-correlated photon-pairs using traveling-wave cascaded nonlinear interactions in a single periodically-poled thin-film lithium-niobate-on-insulator waveguide with >10 coincidence-to-accidental ratio.
Experimental demonstration of robust quantum steering
Authors: Wollmann Sabine , Uola Roope , Costa Ana C. S.
Published: January 2021

We demonstrate quantum steering based on generalised entropies and criteria with minimal assumptions based on the so-called dimension-bounded steering. Further, we investigate their robustness against experimental imperfections such as misalignment in the shared measurement reference-frame.
Passive-state preparation for continuous-variable quantum key distribution
Authors: Qi Bing , Gunther Hyrum , Evans Philip G. , Williams Brian P. , Camacho Ryan M. , Peters Nicholas A.
Published: January 2021

We conduct an experimental study of continuous-variable quantum key distribution using a passive-state preparation scheme. Using an off-the-shelf amplified spontaneous emission source, we show that a secure key can be generated over metro-area distances.
100-MHz dual-comb spectroscopy by pulsed gain-switching of externally injected semiconductor lasers
Authors: Quevedo-Galán C. , Rosado A. , Durán V. , Pérez-Serrano A. , Tijero J.M.G. , Esquivias I.
Published: January 2021

We combine optical injection and pulsed electrical excitation to generate flat-topped 100-MHz optical frequency combs from gain-switched semiconductor lasers. A highly coherent dual-comb system is tested by conducting high-resolution spectroscopy.
Dual-Comb Spectroscopy based on Single Electro-Optic Modulation
Authors: Huh Jeong Hyun , Chen Zaijun , Vicentini Edoardo , Hänsch Theodor W. , Picqué Nathalie
Published: January 2021

A single electro-optic modulator enables near-infrared dual-comb spectroscopy over a span of 40 GHz with a 150-kHz refresh rate and a 50-s coherence time. The signal-to-noise ratio is 950 at 100-MHz resolution and 100-ms measurement.
Frequency Comb Spectroscopy with Coherent Frequency Combs Generated by Diode Lasers
Authors: Day Matthew W. , Dong Mark , Smith Bradley C. , Owen Rachel C. , Kerber Grace C. , Ma Taigo , Winful Herbert G. , Cundiff Steven T.
Published: January 2021

We demonstrate frequency combs generated with electrically pumped, commercially grown, quantum well laser diodes. We characterize their coherent output, and demonstrate dual comb absorption spectroscopy conducted with two free-running combs.
Frequency Comb for Deployed Quantum Timing and Sensing Applications
Authors: Timmers Henry , Tooley Dylan , Sodergren Bennett , Robinson Ryan , Vogel Kurt , Knabe Kevin
Published: January 2021

A low-volume frequency comb has been designed for quantum timing applications outside the laboratory. Performance metrics include signal-to-noise ratios greater than 40 dB and in-loop Allan Deviations below 1 × 10−16/√. © 2020 Vescent Photonics, Inc.
Decay dynamics of matter-wave quantum emitters in a band structure
Authors: Schneble Dominik
Published: January 2021

We present experiments on radiative decay of quantum emitters in a band structure. Our waveguide-QED simulation, which explored variable vacuum couplings and the interplay of bound states, was performed with ultracold atomic matter waves in an optical lattice.
Bound-state Induced Tunneling in an Array of Matter-wave Quantum Emitters Coupled to Free Space
Authors: Kwon Joonhyuk , Kim Youngshin , Lanuza Alfonso , Stewart Michael , Schneble Dominik
Published: January 2021

Bound states in quantum emitter arrays can induce coherent transport though polariton formation. Here, we investigate effects of bound-state induced hopping on motional coherence in an array of matter-wave emitters realized with ultracold atoms in an optical lattice.
High-Spectral-Resolution Imaging Spectroscopy with a Dual-Comb Interferometer
Authors: Vicentini Edoardo , Chen Zaijun , Huh Jeong Hyun , Galzerano Gianluca , Hänsch Theodor W. , Picqué Nathalie
Published: January 2021

Imaging absorption spectroscopy with laser frequency combs simultaneously measures 64 spectra at 250-MHz resolution over a span of 4 nm, within 3 seconds. At 1000 s averaging, the high signal-to-noise ratio reaches 250 per pixel.
First HPLS Experiments at ELI-NP: Spectral Broadening in Thin Films
Authors: Ursescu Daniel , Matei Dan , Talposi Maria , Iancu Vicentiu , Aleksandrov Veselin , Bleotu Gabriel , Naziru Andrei , Tesileanu Ovidiu , Rosu Madalin , Nakamiya Yoshihide , Cernaianu Mihail , de Boisdeffre Bertrand , Ene Costin , Caragea Mihai , Lazar Alexandru , Kiss Miklos , Masruri Masruri , Caratas Loredana , Toader Adrian , Nistor Dmitrii , Luta Vlad , Tatulea Bogdan , Popa Daniel , Stan Nicu , Jitsuno Takahisa , Banici Romeo , Baleanu Andrei , Gradinariu Andrei , Wheeler Jonathan , Mourou Gerard , Dancus Ioan
Published: January 2021

Following the completion of the installation and testing of the HPLS 2x10PW laser system at ELI-NP, prospective experiments related to spectral broadening in thin films for post-compression were performed at the HPLS 100TW output.
Measurement of the spatiotemporal polarization of ultrafast vector beams
Authors: Alonso Benjamín , Lopez-Quintas Ignacio , Holgado Warein , Drevinskas Rokas , Kazansky Peter G. , Hernández-García Carlos , Sola Íñigo J.
Published: January 2021

We perform a complete measurement of ultrashort pulsed beams where the polarization evolves spatially and temporally. We apply our technique to characterize ultrafast shaped vector beams which combine temporal polarization gating and radial polarization.
Low-power and high-detectivity Ge photodiodes by in-situ heavy As doping during Ge-on-Si seed layer growth
Authors: Lin Yiding , Lee Kwang Hong , Son Bongkwon , Tan Chuan Seng
Published: January 2021

Germanium (Ge)-based photodetectors have become one of the mainstream components in photonic-integrated circuits (PICs). Many emerging PIC applications require the photodetectors to have high detectivity and low power consumption. Herein, we demonstrate high-detectivity Ge vertical p-i-n photodiodes on an in-situ heavily arsenic (As)-doped Ge-on-Si platform. The As doping was incorporated during the initial Ge-on-Si seed layer growth. The grown film exhibits an insignificant up-diffusion of the As dopants. The design results in a ∼45× reduction on the dark current and consequently a ∼5× enhancement on the specific detectivity (D*) at low reverse bias. The improvements are mainly attributed to the improved epi-Ge crystal quality and the narrowing of the device junction depletion width. Furthermore, a significant deviation on the AsH3 flow finds a negligible effect on the D* enhancement. This unconventional but low-cost approach provides an alternative solution for future high-detectivity and low-power photodiodes in PICs. This method can be extended to the use of other n-type dopants (e.g., phosphorus (P) and antimony (Sb)) as well as to the design of other types of photodiodes (e.g., waveguide-integrated).
Atomic vapor filter revisited: a Cabannes scattering temperature/wind lidar at 770 nm
Authors: She Chiao-Yao , Krueger David A. , Yan Zhao-Ai , Hu Xiong
Published: January 2021

Using an atomic/molecular vapor as an aerosol blocking filter for atmospheric temperature measurements with a Cabannes lidar is revisited. Different problems in previously used barium and iodine filters prevented them from delivering the 78 times signal advantage (8.8 times less uncertainty) over rotational Raman lidar. We conclude that, despite the sensitivity optimization in rotational Raman lidar, a proposed Cabannes lidar utilizing potassium vapor filters can have 6.1 times less temperature uncertainty. By tuning the laser frequency cyclically to above and below the potassium D1 transition, the lidar system can measure temperature and wind simultaneously.
Intra-oscillator high harmonic generation in a thin-disk laser operating in the 100-fs regime
Authors: Fischer Julian , Drs Jakub , Labaye François , Modsching Norbert , Wittwer Valentin J. , Südmeyer Thomas
Published: January 2021

We demonstrate that Kerr lens modelocking is well-suited for operating an ultrafast thin-disk laser with intra-oscillator high harmonic generation (HHG) in the 100-fs pulse duration regime. Exploiting nearly the full emission bandwidth of the gain material Yb:YAG, we generate 105-fs pulses with an intracavity peak power of 365 MW and an intracavity average power of 470 W. We drive HHG in argon with a peak intensity of ∼7⋅1013 W/cm2 at a repetition rate of 11 MHz. Extreme-ultraviolet (XUV) light is generated up to the 31st harmonic order (H31) at 37 eV, with an average power of ∼0.4 µW in H25 at 30 eV. This work presents a considerable increase in performance of XUV sources based on intra-oscillator HHG and confirms that this approach is a promising technology for simple and portable XUV sources at MHz repetition rates.
Rainbow trapping and releasing in graded grating graphene plasmonic waveguides
Authors: Ghaderian Peyman , Habibzadeh-Sharif Amir
Published: January 2021

In this paper, a graphene plasmonic waveguide consisting of Si graded gratings and a SiO2 separator has been designed in order to rainbow trap and release in the mid-infrared frequencies. Tunability of the light trapping and releasing in this proposed structure has been realized thanks to the adjustable chemical potential of the graphene. Using this structure, the light velocity has been decreased by a slowdown factor above 1270 with a trapping bandwidth of 3.5 µm. Due to the high tunability of this miniaturized structure, it can be used in a variety of applications including optical switches, buffers, and storages.
Generation of watt-level supercontinuum covering 2-6.5 µm in an all-fiber structured infrared nonlinear transmission system
Authors: Yan Bin , Huang Tao , Zhang Weiwang , Wang Juan , Yang Lingling , Yang Peilong , Xia Kai , Bai Shengchuang , Zhao Ruwei , Wu Duanduan , Liu Yongxing , Li Xing , Dai Shixun , Nie Qiuhua
Published: January 2021

We demonstrate a watt-level mid-infrared supercontinuum source, with the spectrum covering the infrared region from 2 to 6.5 µm, in an all-fiber structured laser transmission system. To further improve the SC spectral bandwidth, power and system compactness in the follow-up As2S3 fiber, we theoretically and experimentally explored some knotty problems that would potentially result in the As2S3 fiber end-facet failure and low SC output power during the high-power butt-coupling process and proposed an optimal coupling distance on the premise of the safety of As2S3 fiber end face. In addition, we also built a multi-pulse pumping model for the first time to more precisely estimate the SC spectral evolution in As2S3 fiber. This work will give an important reference to someone who is working on the all-fiber structured, high-power mid- and far-infrared supercontinuum source.
Absorptive metasurface color filters based on hyperbolic metamaterials for a CMOS image sensor
Authors: Hong Jongwoo , Son Hyunwoo , Kim Changhyun , Mun Sang-Eun , Sung Jangwoon , Lee Byoungho
Published: January 2021

Metasurface color filters (MCFs) have attracted considerable attention thanks to their compactness and functionality as a candidate of an optical element in a miniaturized image sensor. However, conventional dielectric and plasmonic MCFs that have focused on color purity and efficiency cannot avoid reflection in principle, which degrades image quality by optical flare. Here, we introduce absorptive-type MCFs through truncated-cone hyperbolic metamaterial absorbers. By applying a particle swarm optimization method to design multiple parameters simultaneously, the proposed MCF is theoretically and numerically demonstrated in perceptive color on CIELAB and CIEDE2000 with suppressed-reflection. Then, a color filter array is numerically proven in 255 nm of sub-pixel pitch.
Polarization-controlled efficient and unidirectional surface plasmon polariton excitation enabled by metagratings in a generalized Kretschmann configuration
Authors: Liu Zeyang , Feng Weijie , Huang Zhanhua , Jay Guo L.
Published: January 2021

In this paper, we propose a generalized Kretschmann configuration that employs a metagrating to replace the prism, realizing polarization-controlled efficient and unidirectional surface plasmon polariton (SPP) excitation. This dielectric phase gradient metagrating on the top surface of a silica substrate is designed to deflect incident light, which subsequently launches SPP wave by means of momentum matching on the metal film coated on the bottom surface. A series of metagratings is designed to enable the SPP excitation by circularly or linearly polarized incident light. The flexibility and tunability of this design to efficiently control SPPs show potential to find wide applications in diverse integrated optics and SPP devices.
Improved saturation and wide-viewing angle color filters based on multi-twist retarders
Authors: Li Lingshan , Shi Shuojia , Escuti Michael J.
Published: January 2021

Birefringent color filters serve a critical role in next-generation display systems, including augmented-/virtual-/mixed-reality headsets, and many types of optical remote sensing. Most prior polarization interference filters (PIFs) employ many individually aligned plates that enable only relatively thick color filters (≥100s of µm), are usually limited to small clear apertures (few cm), and offer poor off-axis performance. Here, we report on a family of monolithic, thin-film, birefringent PIFs formed using liquid crystal polymer (LCP) network materials, also known as reactive mesogens. These multi-twist retarders (MTRs) are only a few µm thick and have a single alignment surface. They offer high color saturation with a notch-type pass/stopband, analogous to Solc PIFs and stable off-axis performance. Here, we apply simplifying assumptions inspired by Solc PIFs, and develop a design method resulting in MTRs with an alternating achiral/chiral architecture. We theoretically and experimentally presented three types of MTR color filters (blue-yellow, green-magenta, and cyan-red), which manifest strong color filtering behavior and improved angular performance (up to ±20°) with larger color space coverage and high total light efficiency compared to their Solc filters counterparts. Such high-saturated and wide-viewing MTR color filters can be promising elements to maintain the system field of view (FOV) in the next-generation displays or spectral imaging applications.
Service restoration in multi-modal optical transport networks with reinforcement learning
Authors: Zhao Zipiao , Zhao Yongli , Li Yajie , Wang Feng , Li Xinghua , Han Dahai , Zhang Jie
Published: January 2021

Optical transport networks (OTNs), while increasingly popular, can be affected in ways that are challenging to restore efficiently. This study investigates the problem of service restoration under OTNs with an optical channel data unit (ODU)-k switching capability (OTN-OSC) environment. An advantage actor-critic-based service restoration (A2CSR) algorithm is presented with the objective of increasing the service restoration rate. In our experimental setup, A2CSR uses the advanced image recognition model MobileNetV2 and an advantage actor-critic reinforcement learning algorithm. Simulation results show that the proposed A2CSR algorithm can achieve better blocking probability and resource utilisation than the benchmark algorithm (first fit (FF)), and the restoration time is within the acceptable range.
Compact dual band/dual FOV infrared imaging system with freeform prism
Authors: Yu Jun , Shen Zhengxiang , Wang Zhanshan
Published: January 2021

For higher detection capability, dual band/dual field of view (FOV) infrared imaging systems are often used to recognize camouflaged targets. In this Letter, we report a dual band/dual FOV infrared imaging system with freeform prism, in which the optical path is folded drastically. Each spectral band will pass through the same entrance pupil and then is split off by a beam splitter so that each spectral band can match a different FOV. Compared to traditional infrared imaging systems, the proposed system has advantages of less volume, higher integration, and optical efficiency.
Ultra-low frequency dynamic strain detection with laser frequency drifting compensation based on a random fiber grating array
Authors: Wang Yuan , Lu Ping , Mihailov Stephen , Chen Liang , Bao Xiaoyi
Published: January 2021

Dynamic strain sensing over a frequency range from 0.01 to 20 Hz can be used for monitoring earthquakes and volcanoes, charting rock and petroleum formations beneath the earth. However, significant laser frequency drifting (LFD) has limited the detection in this frequency range, especially for distributed frequency detection with phase optical time domain reflectometry (OTDR), where the LFD will introduce a time dependent noise destroying the dynamic strain reconstruction. In this study, a simple and effective method that utilizes the referenced random fiber grating to monitor the variation of laser frequency has been both theoretically analyzed and experimentally demonstrated. During the maximum up to 200 s data acquisition time, the frequency variation of a distributed feedback (DFB) laser with MHz linewidth is obtained from the referenced portion of sensing signal, and then the 1 Hz and 0.01 Hz dynamic strain variations with amplitude of 30 µ

ε

are reconstructed with strain measurement standard deviation of 66 n

ε

. Due to signal-to-noise ratio (SNR) enhanced Rayleigh traces from random fiber gratings, a minimum detectable frequency drifting of 7.28 MHz could be achieved over the optical frequency of

2

×

10

14

H
z

.
Efficient second-harmonic generation in high Q-factor asymmetric lithium niobate metasurfaces
Authors: Kang Lei , Bao Huaguang , Werner Douglas H.
Published: January 2021

Lithium niobate (LN) has been widely used for second-harmonic generation (SHG) from bulk crystals. Recent studies have reported improved SHG efficiency in LN micro-ring resonators and hybrid waveguiding structures, as well as in LN nanostructures supporting anapole modes and plasmon-assisted dipole resonances. Here we numerically demonstrate that high

Q

-factor resonances associated with symmetry-protected bound states in the continuum can lead to highly efficient frequency doubling in LN metasurfaces. Simulations show that the radiative

Q

-factor and on-resonance field enhancement factor observed in the metasurface are closely dependent on the asymmetric parameter

α

of the system. Furthermore, high

Q

-factor resonances boost the SH conversion process in the LN nanostructures. In particular, for a LN metasurface with a

Q

-factor of

∼

8

×

10

4

, a 0.49% peak SH conversion efficiency is achieved at a pump intensity of

3.3

k
W

/

c
m

2

. This suggests that such high

Q

-factor LN metasurfaces may be good candidates for practical blue–ultraviolet light sources. Our work provides insight into the possible implementation of metadevices based on nanoengineering of conventional nonlinear crystals.
Burst-mode dual-comb spectroscopy
Authors: Zhang Yu , Weeks Reagan R. D. , Lecaplain Caroline , Harilal Sivanandan S. , Yeak Jeremy , Phillips Mark C. , Jones R. Jason
Published: January 2021

We introduce a new, to the best of our knowledge, modality of dual-comb spectroscopy (DCS) that enables a simplified and powerful new approach for time-resolved measurements with increased acquisition rates. This “burst mode” form of DCS relies on the multiplexing of each probe pulse into a short train of pulses. With this approach we demonstrate a time-resolved series of absorption-based spectroscopic measurements of a laser-induced plasma using only a single laser ablation shot and identify 22 Nd lines not previously reported in the literature. The transmission spectra spanned 3.1 THz and were acquired at an effective acquisition rate of 25 kHz with 40 µs time resolution. This simple modification to

∼

100

M
H
z

level dual-comb systems provides a flexible approach for studying transient and low-duty-cycle events such as laser-induced plasmas, combustion, and explosive reactions.
Temporal stability of calibration functions in the traditional pure rotational Raman lidar technique
Authors: Gerasimov Vladislav V.
Published: January 2021

Pure rotational Raman (PRR) lidars should be calibrated to measure atmospheric temperature. In the frame of the traditional PRR technique, the lidar calibration represents the determination of calibration function (CF) coefficients using a reference temperature profile from an atmosphere model or radiosonde data. When a measurement campaign lasts several days, the accuracy of temperature retrieval from PRR lidar signals depends on the temporal stability of the selected CF. In this paper, we present a simple way to intercompare different CFs and determine the most stable function in time among them. We study to what extent the CF coefficients determined on one of the measurement campaign days may be used for temperature retrieval on the other days. We also examine the situation when reference radiosonde data are absent on one of the measurement days and, therefore, the CF coefficients need to be determined from reference data over the remaining days. The 1-week and 3-day temporal stabilities of five CFs are studied on the example of nighttime temperature profiles retrieved from PRR lidar measurements of 1, 6, 7, and 8 April 2015. The stability of these CFs is studied for the first time. The measurements were performed in Tomsk (56.48°N, 85.05°E, Western Siberia, Russia) using a PRR lidar of the Institute of Monitoring of Climatic and Ecological Systems (IMCES). The CF retrieving temperature of the troposphere (3–9 km) with the highest accuracy for the considered 1-week and 3-day measurement periods is determined for the IMCES lidar.
Development, validation, and pilot MRI safety study of a high-resolution, open source, whole body pediatric numerical simulation model
Authors: Jeong Hongbae , Ntolkeras Georgios , Alhilani Michel , Atefi Seyed Reza , Zöllei Lilla , Fujimoto Kyoko , Pourvaziri Ali , Lev Michael H. , Grant P. Ellen , Bonmassar Giorgio
Published: January 2021

Numerical body models of children are used for designing medical devices, including but not limited to optical imaging, ultrasound, CT, EEG/MEG, and MRI. These models are used in many clinical and neuroscience research applications, such as radiation safety dosimetric studies and source localization. Although several such adult models have been reported, there are few reports of full-body pediatric models, and those described have several limitations. Some, for example, are either morphed from older children or do not have detailed segmentations. Here, we introduce a 29-month-old male whole-body native numerical model, “MARTIN”, that includes 28 head and 86 body tissue compartments, segmented directly from the high spatial resolution MRI and CT images. An advanced auto-segmentation tool was used for the deep-brain structures, whereas 3D Slicer was used to segment the non-brain structures and to refine the segmentation for all of the tissue compartments. Our MARTIN model was developed and validated using three separate approaches, through an iterative process, as follows. First, the calculated volumes, weights, and dimensions of selected structures were adjusted and confirmed to be within 6% of the literature values for the 2-3-year-old age-range. Second, all structural segmentations were adjusted and confirmed by two experienced, sub-specialty certified neuro-radiologists, also through an interactive process. Third, an additional validation was performed with a Bloch simulator to create synthetic MR image from our MARTIN model and compare the image contrast of the resulting synthetic image with that of the original MRI data; this resulted in a “structural resemblance” index of 0.97. Finally, we used our model to perform pilot MRI safety simulations of an Active Implantable Medical Device (AIMD) using a commercially available software platform (Sim4Life), incorporating the latest International Standards Organization guidelines. This model will be made available on the Athinoula A. Martinos Center for Biomedical Imaging website.
Patient harm associated with serial phlebotomy and blood waste in the intensive care unit: A retrospective cohort study
Authors: Bodley Thomas , Chan Maverick , Levi Olga , Clarfield Lauren , Yip Drake , Smith Orla , Friedrich Jan O. , Hicks Lisa K.
Published: January 2021

Background

Intensive care unit (ICU) patients are at high risk of anemia, and phlebotomy is a potentially modifiable source of blood loss. Our objective was to quantify daily phlebotomy volume for ICU patients, including blood discarded as waste during vascular access, and evaluate the impact of phlebotomy volume on patient outcomes.

Methods

This was a retrospective observational cohort study between September 2014 and August 2015 at a tertiary care academic medical-surgical ICU. A prospective audit of phlebotomy practices in March 2018 was used to estimate blood waste during vascular access. Multivariable logistic regression was used to evaluate phlebotomy volume as a predictor of ICU nadir hemoglobin < 80 g/L, and red blood cell transfusion.

Results

There were 428 index ICU admissions, median age 64.4 yr, 41% female. Forty-four patients (10%) with major bleeding events were excluded. Mean bedside waste per blood draw (144 draws) was: 3.9 mL from arterial lines, 5.5 mL central venous lines, and 6.3 mL from peripherally inserted central catheters. Mean phlebotomy volume per patient day was 48.1 ± 22.2 mL; 33.1 ± 15.0 mL received by the lab and 15.0 ± 8.1 mL discarded as bedside waste. Multivariable regression, including age, sex, admission hemoglobin, sequential organ failure assessment score, and ICU length of stay, showed total daily phlebotomy volume was predictive of hemoglobin <80 g/L (p = 0.002), red blood cell transfusion (p<0.001), and inpatient mortality (p = 0.002). For every 5 mL increase in average daily phlebotomy the odds ratio for nadir hemoglobin <80 g/L was 1.18 (95% CI 1.07–1.31) and for red blood cell transfusion was 1.17 (95% CI 1.07–1.28).

Conclusion

A substantial portion of daily ICU phlebotomy is waste discarded during vascular access. Average ICU phlebotomy volume is independently associated with ICU acquired anemia and red blood cell transfusion which supports the need for phlebotomy stewardship programs.
Exercise modifies glutamate and other metabolic biomarkers in cerebrospinal fluid from Gulf War Illness and Myalgic encephalomyelitis / Chronic Fatigue Syndrome
Authors: Baraniuk James N. , Kern Grant , Narayan Vaishnavi , Cheema Amrita
Published: January 2021

Myalgic encephalomyelitis / Chronic Fatigue Syndrome (ME/CFS) and Gulf War Illness (GWI) share many symptoms of fatigue, pain, and cognitive dysfunction that are not relieved by rest. Patterns of serum metabolites in ME/CFS and GWI are different from control groups and suggest potential dysfunction of energy and lipid metabolism. The metabolomics of cerebrospinal fluid was contrasted between ME/CFS, GWI and sedentary controls in 2 sets of subjects who had lumbar punctures after either (a) rest or (b) submaximal exercise stress tests. Postexercise GWI and control subjects were subdivided according to acquired transient postexertional postural tachycardia. Banked cerebrospinal fluid specimens were assayed using Biocrates AbsoluteIDQ® p180 kits for quantitative targeted metabolomics studies of amino acids, amines, acylcarnitines, sphingolipids, lysophospholipids, alkyl and ether phosphocholines. Glutamate was significantly higher in the subgroup of postexercise GWI subjects who did not develop postural tachycardia after exercise compared to nonexercise and other postexercise groups. The only difference between nonexercise groups was higher lysoPC a C28:0 in GWI than ME/CFS suggesting this biochemical or phospholipase activities may have potential as a biomarker to distinguish between the 2 diseases. Exercise effects were suggested by elevation of short chain acylcarnitine C5-OH (C3-DC-M) in postexercise controls compared to nonexercise ME/CFS. Limitations include small subgroup sample sizes and absence of postexercise ME/CFS specimens. Mechanisms of glutamate neuroexcitotoxicity may contribute to neuropathology and “neuroinflammation” in the GWI subset who did not develop postural tachycardia after exercise. Dysfunctional lipid metabolism may distinguish the predominantly female ME/CFS group from predominantly male GWI subjects.
Farming systems in sheep rearing: Impact on growth and reproductive performance, nutrient digestibility, disease incidence and heat stress indices
Authors: Karthik D. , Suresh J. , Reddy Y. Ravindra , Sharma G. R. K. , Ramana J. V. , Gangaraju G. , Pradeep Kumar Reddy Y. , Yasaswini D. , Adegbeye M. J. , Reddy P. Ravi Kanth
Published: January 2021

The experiment was conducted with an intent to know the effect of different farming systems on the growth performance, nutrient digestibility coefficients, reproductive traits, disease incidence, heat stress indices, and cost economics of Nellore sheep. The study includes two parallel trials to prevent the influence of age on heat stress indices (panting score and erythrocyte osmotic fragility (EOF)). One hundred and twenty lambs (60 ram-lambs and 60 ewe-lambs) were allotted in a randomized block design under extensive, semi-intensive, and intensive systems for trial I, whereas trial II include eighteen rams assigned to the three respective farming systems in a completely randomised design. Both, season (summer) and grazing practice increased the panting score and EOF. The heat stress indices were positively correlated (P<0.01) with dry-bulb temperature and temperature-humidity index (THI) and inversely correlated (P<0.01) to relative humidity. Allotting the sheep to intensive system increased (P<0.001) weight gain and average daily gain with higher effect in males compared to females. The parameters of asymptotic weight (A), integration constant (B), and maturation rate were higher for intensive males. The male Nellore lambs had higher asymptotic weight and lower maturity rate than females, irrespective of the rearing system. Intensive sheep revealed a higher dry matter intake, digestibility coefficients, feed conversion ratio. The instantaneous bite mass (IBM) was higher for Commelina benghalensis, while instantaneous bite frequency (IBF), instantaneous intake rate (IIR) were higher for Cyanodon dactylon and amaranthus viridis, respectively. The proportion of intakes were highest for Stylo hemata followed by Cynodon dactylon and Tridax procumbens species. No differences were observed for the weight at puberty, oestrus cycle length, oestrus duration, conception percent, gestation period, and lambing percent in three rearing systems; however, the age at puberty was lower (P<0.001) and the birth weight was higher (P<0.001) for sheep reared under intensive farming system. Highest disease incidence was observed in rainy and winter seasons, particularly in sheep reared under extensive system. The capital expenditure was same for the three rearing systems, while the recurring expenditure was higher for Intensive farming system. The gross income and net income were higher for intensive system on account of higher weight gains. However, the higher returns per rupee of expenditure project the extensive farming as an ideal rearing system for small farmers and entrepreneurs with a low initial capital.