Ultra-wide Range Research Articles

Core Selective Switch With Low Insertion Loss Over Ultra-Wide Wavelength Range for Spatial Channel Networks

The core selective switch (CSS) is an optical spatial switch that has been recently proposed as a key building block to achieve a scalable and low-insertion-loss spatial cross-connects for use in future spatial channel networks. In this paper, we report on a novel CSS design employing a two dimensionally arranged microlens-based multicore fiber (MCF) collimator array and a micro-electromechanical systems (MEMS) mirror array. The former enables precise alignment between MCFs and collimator lenses, and the latter yields polarization-independent high reflection over a wide wavelength range and a large tilt angle. Based on the design, a compact (∼50 mm) five-core <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$1 \times 8$</tex-math></inline-formula> CSS prototype is fabricated. We experimentally show that the CSS prototype exhibits low insertion loss (1.2∼2.7 dB), low polarization dependent loss (< 0.25 dB), and low crosstalk (< <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$ - 30$</tex-math></inline-formula> dB) characteristics over an ultra-wide wavelength range from 1500 nm to 1630 nm. Bit-error-rate measurements using optical signals in the C-band, S-band, and L-band show that the CSS prototype incurs no optical signal-to-noise ratio penalty in spatial channel routing over an ultra-wide wavelength band.

Extreme mechanical metamaterials with independently adjustable elastic modulus and mass density

The mechanical properties of artificially periodic structures are closely related to the geometric dimensions of the structures. In this letter, we derive analytical expressions for the equivalent elastic parameters of a hexagonal cellular structure with additional counterweight mass blocks, and the accuracy of these analytical expressions is verified by numerical results. By analyzing the analytical expressions, we rigorously demonstrate an approximate decoupling relationship between the elastic modulus and mass density. Finally, we creatively propose a structure that can simultaneously achieve perfect decoupling of elastic modulus and mass density as well as flexible adjustment of material parameters in an ultra-wide range.

Ti3C2Tx MXene/Bamboo Fiber/PDMS Pressure Sensor with Simultaneous Ultrawide Linear Sensing Range, Superb Environmental Stability, and Excellent Biocompatibility

Ti3C2Tx MXene has drawn remarkable attention in electronic sensors. Existing MXene-based pressure sensors generally have a narrow linear sensing range, which limits their wide application. Moreover, previous studies on MXene-based pressure sensors were mainly focused on increasing sensitivity via various microengineering techniques, but little attention has been paid to environmental stability and biocompatibility of these sensors. Herein, a highly flexible, biocompatible, and environmentally stable Ti3C2Tx MXene/bamboo cellulose fiber (BCF)/poly(dimethylsiloxane) (PDMS) composite pressure sensor with an ultrawide working range (up to 2 MPa), a high linearity (R2 = 0.966), and long-term stability is demonstrated. First, the MXene/BCF (MB) foam with well-optimized porosity and connectivity was prepared through an efficient freeze-drying method. Then, the MB-based piezoresistive composite (PMB) was obtained by directly embedding the MB foams into PDMS elastomers. In striking contrast to previous MXene composite-based pressure sensors, the PMB pressure sensor exhibits not only excellent pressure sensing performance and good biocompatibility but also prominent work reliability to resist temperature fluctuation, moisture/water, and UV irradiation. Furthermore, to demonstrate the potential of the PMB pressure sensor, various human movements under both ambient and harsh environmental conditions were monitored. Finally, the PMB pressure sensor was also successfully integrated with soft robotic hands to show its great potential in robotic tactile sensation.

Screen-printing of core-shell Mn3O4@C nanocubes based sensing microchip performing ultrasensitive recognition of allura red

Allura red (AR) is a member of azo dyes is commonly used as an additive in foods and soft drinks. However, due to the special harm of the azo structure to the human body, the dosage control of AR becomes particularly necessary. The present detection methods are time-consuming, expensive and complicated. In order to address the above issues, a core-shell nanocubes constructed sensor has been developed to determine the ultrawide detection range and selective recognition of AR with a long-term reusability. The core-shell architecture is composed of carbon material of 12.64 nm thickness covering 600 nm Mn3O4 nanocube. This nanocomposite combines the advantages of Mn3O4@C, possessing high electrocatalysis and chemical stability. As confirmed in using sports drinks as real samples, the as-prepared AR sensor exhibites excellent selectivity with an ultra-wide linear range from 0.1 to 1748.4 μM, and meanwhile, this sensor can also meet the requirements of remarkable anti-interference and reusability over 30 days.

Ultrawide-Angle and High-Scanning-Rate Leaky Wave Antenna Based on Spoof Surface Plasmon Polaritons

An ultrawide-angle frequency beam scanning leaky-wave antenna (LWA) with a high scanning rate based on spoof surface plasmon polaritons (SSPPs) waveguide is proposed in this communication. A row of elliptical patches is placed periodically near the SSPPs waveguide, which can shift the fundamental mode of SSPPs waveguide to the fast-wave region and radiate electromagnetic (EM) waves. The simulated results show that the proposed LWA achieves an ultrawide scanning angle range of 172° over a narrow operation bandwidth of 9.8–12.28 GHz, which implies a high scanning rate. The simulated average gain of the proposed LWA is 10.13 dBi and its average total efficiency is 75.35%. The proposed LWA is fabricated and measured. The measured scanning angle range is 167° in the frequency band of 9.9–12.25 GHz, and the measured average gain is 9.73 dBi. Good agreements between the simulated and measured results are obtained, validating the proposed design.

Single-sideband microwave-to-optical conversion in high-Q ferrimagnetic microspheres

Coherent conversion of microwave and optical photons can significantly expand the capabilities of information processing and communications systems. Here, we experimentally demonstrate the microwave-to-optical frequency conversion in a magneto-optical whispering gallery mode microcavity. By applying a magnetic field parallel to the microsphere equator, the intracavity optical field will be modulated when the magnon is excited by the microwave drive, leading to a microwave-to-optical conversion via the magnetic Stokes and anti-Stokes scattering processes. The observed single-sideband conversion phenomenon indicates a nontrivial optical photon–magnon interaction mechanism derived from the magnon that induced both the frequency shift and modulated coupling rate of optical modes. In addition, we demonstrate the single-sideband frequency conversion with an ultrawide tuning range up to 2.5 GHz, showing its great potential in microwave-to-optical conversion.

High-entropy (Ca0.5Ce0.5)(Nb0.25Ta0.25Mo0.25W0.25)O4 scheelite ceramics with high-temperature negative temperature coefficient (NTC) property for thermistor materials

(Ca0.5Ce0.5)(Nb0.25Ta0.25Mo0.25W0.25)O4 high-entropy ceramics with single scheelite phase structure were synthesized by solid-state reactions under a reducing atmosphere of argon, and their high-temperature electrical properties were investigated. The single scheelite phase of high-entropy ceramics is fabricated at a sintering temperature of 1300 °C, and grain sizes as well as relative densities of high-entropy ceramics increase with the increase of sintering temperature. High-entropy ceramics sintered at 1300 °C and 1400 °C exhibit excellent negative temperature coefficient (NTC) property within an ultrawide temperature range of 150 °C-1200 °C. Ceramic samples sintered under Ar tend to have lower activation energy, for the higher Ce3+ contents they possess than those sintered under air are in favor of increasing their polaron concentration. In comparison with conventional scheelite ceramics, high-entropy scheelite ceramics have a unitary NTC mechanism within a wider temperature range and a better aging property, for their crystal structure is stabilized by high-entropy effect at higher temperature.

Analysis of a bidirectional metamaterial perfect absorber with band-switchability for multifunctional optical applications

Metamaterial perfect absorbers (MPAs) have been widely studied due to their distinctive tunable electromagnetic properties. Conventional MPAs mostly focus on realizing perfect absorption in a single direction, which leads to their limitations for various practical applications. We propose a bidirectional MPA with the ability of switching the ultra-wideband and dual-narrowband absorption. An inversion algorithm is applied to extract the normalized impedance of the absorber for explaining the physical mechanism. Simulation results clearly manifest that the average absorptivity of 93.8% and 99.5% could be achieved both over an ultra-wide spectral range of 1200 nm and at the specific wavelengths of 589 nm and 1097 nm with polarization independence and angle insensitiveness, which are led by the multiple excitations of different resonance modes induced by the metal–insulator-metal (MIM) Fabry-Perot (F-P) cavities. Our results are desirable for the integration of multiple optical applications such as energy harvesting, thermal emission, perfect cloaking and nanoparticle detecting.

Periodic and aperiodic 3-D composite metastructures with ultrawide bandgap for vibration and noise control

Periodic composite structures as acoustic metamaterials have caught enormous research interest for the inherent peculiar dynamics characteristics, effective medium properties, and fantastic mechanical features to control vibration and noises at deep subwavelength scales. A 3-D composite metastructure design endowed with ultrawide three-dimensional bandgap is highly desirable for low frequency broadband vibration and noise control. In that context, the present study proposes two types of 3-D composite mechanical metastructure unit cell designs that are capable enough to induce low frequency ultrawide bandgaps by principle of mode separation. A 3-D polymeric casing is designed and spherical/cylindrical steel masses are embedded to enhance the dynamical characteristics and mechanical properties of the resonant systems. By a numerical study on wave dispersion, the presence of ultrawide bandgap and governing physical mechanism resulting in such broadband bandgap are discussed. An asymptotic parametric study is performed to investigate the effect of metastructure geometric parameters on the reported bandgaps. We performed numerical and experimental frequency response study on the periodic and aperiodic arrangements of the composite metastructures to envisage wave attenuation inside the bandgaps. Both periodic and aperiodic arrays of metastructures yield vibration attenuation over ultrawide frequency range that is promising for low frequency broadband vibration and noise control applications. The proposed composite metastructure design morphology and manufacturing/fabrication processes are also explained for practical design and applications. The proposed mechanical metastructure designs, our modelling technique, research methodology, and the reported findings may contribute to the design and application of metadevices where low frequency broadband vibration and noise control are desirable.

Low-power RF signal detection with wideband range based on an optically injected optoelectronic oscillator.

A novel method to detect a low-power radio-frequency (RF) signal with ultra-wide frequency range based on an optically injected optoelectronic oscillator (OEO) is proposed and experimentally demonstrated. The optical injection to a distributed feedback (DFB) laser has the advantages of amplifying one sideband of the modulated optical signal selectively and a wide tunable frequency range. The detection upper range that reaches up to 26 GHz and can be improved theoretically. To the best of the authors' knowledge, this is the widest detection range based on an OEO. At the same time, the detection characteristics are good. The sensitivity of the system is -92 dBm and the maximum gain is 12.18 dB at 15.047 GHz. Considering the real application of the detection system, the properties such as dynamic range and performance for detecting a modulated RF signal are also investigated.

Ultrawide Range and High‐precision Temperature Monitoring based on NiO/Polyimide Hybrid Nanomaterials

AbstractThe need for temperature observation appears in all aspects of our lives. With the development of science and technology, higher requirements are put forward for the combination of high‐accuracy and wide detection range of the sensor. In this study, a facile strategy method was developed to prepare a NiO slurry and realize a wide‐range and high‐precision thermistor based on NiO. By dispersing NiO nanoparticles in polyimide (PI) to afford the NiO slurry, a thermistor was obtained by spin coating, thermal curing, and electrode preparation, which can operate in a very wide range from 220 K to 470 K, as well as exhibited an outstanding thermal sensitivity (B) with a value exceeding 5400 K. Moreover, the sensor shows very high detection accuracy and can detect small temperature differences up to 0.05 K. Notably, through brushing the mixture onto the PI substrate or peeling off from the substrate, a flexible, or free‐stand sensor was obtained, which displayed great mechanical properties and stabilities. This allows the sensor to be used on various curved surfaces and other objects with complex shapes, which greatly increases potential applications and the scope of the temperature sensor.

Design of a Sub-6 GHz Dielectric Resonator Antenna with Novel Temperature-Stabilized (Sm1-xBix)NbO4 (x = 0-0.15) Microwave Dielectric Ceramics.

Microwave dielectric ceramics exhibiting a low dielectric constant (εr), high quality factor (Q × f), and thermal stability, specifically in an ultrawide temperature range (from -40 to +120 °C), have attracted much attention. In addition, the development of 5G communication has caused an urgent demand for electronic devices, such as dielectric resonant antennas. Hence, the feasibility of optimizing the dielectric properties of the SmNbO4 (SN) ceramics by substituting Bi3+ ions at the A site was studied. The permittivity principally hinges on the contribution of Sm/Bi-O to phonon absorption in the microwave range, while the reduced sintering temperature results in a smaller grain size and slightly lower Q × f value. The expanded and distorted crystal cell indicates that Bi3+ doping effectively regulates the temperature coefficient of resonant frequency (TCF) by adjusting the strains (causing the distorted monoclinic structure) of monoclinic fergusonite besides correlating with the permittivity. Moreover, a larger A-site radius facilitates the acquisition of near-zero TCF values. Notably, the (Sm0.875Bi0.125)NbO4 (SB0.125N) ceramic with εr ≈ 21.9, Q × f ≈ 38 300 GHz (at ∼8.0 GHz), and two different near-zero TCF values of -9.0 (from -40 to +60 °C) and -6.6 ppm/°C (from +60 to +120 °C), respectively, were obtained in the microwave band. A simultaneous increase in the phase transition temperature (Tc) and coefficients of thermal expansion (CTEs) by A-site substitution provides the possibility for promising thermal barrier coating (TBC) materials. Then, a cylindrical dielectric resonator antenna (CDRA) with a resonance at 4.86 GHz and bandwidth of 870 MHz was fabricated by the SB0.125N specimen. The exceptional performance shows that the SB0.125N material is a possible candidate for the sub-6 GHz antenna owing to the advantages of low loss and stable temperature.

Bioinspired Self-Powered Piezoresistive Sensors for Simultaneous Monitoring of Human Health and Outdoor UV Light Intensity.

The exact fabrication of precise three-dimensional structures for piezoresistive sensors necessitates superior manufacturing methods or tooling, which are accompanied by time-consuming processes and the potential for environmental harm. Herein, we demonstrated a method for in situ synthesis of zinc oxide nanorod (ZnO NR) arrays on graphene-treated cotton and paper substrates and constructed highly sensitive, flexible, wearable, and chemically stable strain sensors. Based on the structure of pine trees and needles in nature, the hybrid sensing layer consisted of graphene-attached cotton or paper fibers and ZnO NRs, and the results showed a high sensitivity of 0.389, 0.095, and 0.029 kPa-1 and an ultra-wide linear range of 0-100 kPa of this sensor under optimal conditions. Our study found that water absorption and swelling of graphene fibers and the associated reduction of pore size and growth of zinc oxide were detrimental to pressure sensor performance. A random line model was developed to examine the effects of different hydrothermal times on sensor performance. Meanwhile, pulse detection, respiration detection, speech recognition, and motion detection, including finger movements, walking, and throat movements, were used to show their practical application in human health activity monitoring. In addition, monolithically grown ZnO NRs on graphene cotton sheets had been integrated into a flexible sensing platform for outdoor UV photo-indication, which is, to our knowledge, the first successful case of an integrated UV photo-detector and motion sensor. Due to its excellent strain detection and UV detection abilities, these strategies are a step forward in developing wearable sensors that are cost-controllable and high-performance.

Tailoring microstructures in (Ni/NiO)@C composites via facile route for broadband microwave absorption

The pollution of microwave radiation has gradually become a serious problem at the current stage. In the accepted method of material absorption, the rational regulation of electromagnetic parameters in composites via adjustment of their microstructures is an effective strategy to enhance their microwave absorbing ability. Herein, a kind of (Ni/NiO)@C composite with radial structure was obtained by co-hydrothermal and annealing method. The results show that the microstructure of composite could be regulated by adjusting the additional content of PTA, thus the commendable interface and dipole polarization, eddy current and exchange resonance loss, multiple reflection and scattering loss can be gathered together to absorb incident microwave. The optimal effective absorption bandwidth of as-prepared composite can reach an ultra-wide frequency range of 9.07 GHz for a great application at the thickness of only 1.79 mm, although the maximal reflected loss is −18.45 dB at 14.58 GHz for 1.5 mm thickness. The work reported here provides a facile route to modulate the self-organizing microstructure in composite and realize the wider band of microwave absorption.

Giant and bidirectionally tunable thermopower in nonaqueous ionogels enabled by selective ion doping.

Ionic thermoelectrics show great potential in thermal sensing owing to their ultrahigh thermopower, low cost, and ease in production. However, the lack of effective n-type ionic thermoelectric materials seriously hinders their applications. Here, we report giant and bidirectionally tunable thermopowers within an ultrawide range from −15 to +17 mV K−1 in solid ionic liquid–based ionogels. Particularly, a record high negative thermopower of −15 mV K−1 is achieved in the ternary ionogel, rendering it among the best n-type ionic thermoelectric materials under the same condition. A thermopower regulation strategy through ion doping to selectively induce ion aggregates to enhance ion-ion interactions is proposed. These selective ion interactions are found to be decisive in modulating the sign and magnitude of the thermopower in the ionogels. A prototype wearable device integrated with 12 p-n pairs is demonstrated with a total thermopower of 0.358 V K−1, showing promise for ultrasensitive thermal detection.

Ultra-Wideband and Lightweight Electromagnetic Polarization Converter Based on Multiresonant Metasurface

Polarization-control devices have attracted considerable interest, however, most of the polarization converters operating at lower frequencies have a heavy design and narrow bandwidth which limits their practical applications. Here we report a simple design of an ultra-wideband and lightweight polarization converter for applications in the S- and C-bands. The proposed converter is designed based on a metasurface structure with the dielectric layer modified to hollow structure to obtain a lightweight design even working at such low frequency. Theoretical analysis and simulation results indicate that the converter can convert the orthogonal polarization transformation of reflected wave. Furthermore, the measurement results show good agreement with the simulation results. The proposed polarization converter can achieve a polarization conversion ratio above 90% in an ultra-wide frequency range from 2 to 8.45 GHz due to multi-resonance modes. These performances are going beyond state of the art in terms of bandwidth and lightweight design, thus it can be applied in various applications in the operating bands.

Ultrahigh-temperature film capacitors via homo/heterogeneous interfaces

Ultra-high temperature performances are achieved by introducing and engineering homogeneous/heterogeneous interfaces within the capacitors. The ultra-wide working temperature range from −100 to 400 °C is suitable for extreme environments.

Diamond spin quantum sensing under extreme conditions

Extreme conditions, such as ultra-low temperatures, high pressures, and strong magnetic fields, are critical to producing and studying exotic states of matter. To measure physical properties under extreme conditions, the advanced sensing schemes are required. As a promising quantum sensor, the diamond nitrogen-vacancy (NV) center can detect magnetic field, electronic field, pressure, and temperature with high sensitivity. Considering its nanoscale spatial resolution and ultra-wide working range, the diamond quantum sensing can play an important role in frontier studies involving extreme conditions. This paper reviews the spin and optical properties of diamond NV center under extreme conditions, including low temperature, high temperature, zero field, strong magnetic fields, and high pressures. The opportunities and challenges of diamond quantum sensing under extreme conditions are discussed. The basic knowledge of spin-based quantum sensing and its applications under extreme conditions are also covered.

Ascorbic acid functionalized anti-aggregated Au nanoparticles for ultrafast MEF and SERS detection of tartrazine: an ultra-wide piecewise linear range study.

Tartrazine, as a synthetic food colorant, is harmful to health upon excessive intake. In this study, we developed a simple, sensitive and ultrafast method to detect tartrazine effectively. Specifically, we successfully used ascorbic acid-functionalized anti-aggregated Au nanoparticles (AuNPs) as enhanced substrates to detect tartrazine in drinks using metal enhanced fluorescence (MEF) and surface-enhanced Raman scattering (SERS) piecewise linearly. The fluorescence intensity and Raman signals of the tartrazine solution enhanced after the addition of AuNPs. There was a good linear correlation between the fluorescence intensity and the concentration of tartrazine from 2.0 μM to 40.0 μM, and the limit of detection (LoD) was 15.4 nM. In addition, the Raman intensity also increased linearly with an increase in the concentration of tartrazine in a wide range (1.0 × 10-5 μM to 1.0 × 10-1 μM) and a lower LoD (0.8 pM) was achieved compared with the results from the fluorescence technique. Both fluorescence and SERS can immediately detect tartrazine in drinks after the substrate was mixed with analytes. Hence, the as-prepared anti-aggregated AuNPs as substrate material achieved a highly sensitive, selective and ultrafast detection of tartrazine via fluorescence and Raman techniques in a wide detection range, providing a novel strategy for the detection of food additives.

Photoacoustic simultaneous detection of multiple trace gases for industrial park application

The determination of toxic or harmful gases in industrial parks is a challenge to monitoring exhaust contaminants due to the features of complex compositions and ubiquity. Blackbody sources play an important role in simultaneously detecting the multiple gas species in the presence of cross-interfering absorption lines due to their effective ultra-wide wavelength range. Nevertheless, the problem of lower intensity per wavelength and less stability persists as an obstacle for highly sensitive trace gas detection. In this study, a dual optical path (DOP) enhanced differential photoacoustic and spectral detection mode is developed for simultaneously detecting the multiple toxic or harmful gas through augmenting the weak effective absorption signals and suppressing the spurious coherent background noise. Two identical T-type photoacoustic resonators are introduced to enable the differential mode. Neverthelss, the pure optical approach cannot distinguish the absorption characteristics of acetylene (C&lt;sub&gt;2&lt;/sub&gt;H&lt;sub&gt;2&lt;/sub&gt;) with volume fraction 5 × 10&lt;sup&gt;–5&lt;/sup&gt; even with the DOP enhancement, whereas emerging peaks in the differential photoacoustic (PA) mode reveal the capability of PA spectroscopy to suppress coherent noise. The results demonstrate that the differential PA signal is improved by 1.91 times that obtained by the DOP design. Methane (NH&lt;sub&gt;3&lt;/sub&gt;), acetylene (C&lt;sub&gt;2&lt;/sub&gt;H&lt;sub&gt;2&lt;/sub&gt;) and carbon dioxide (CO&lt;sub&gt;2&lt;/sub&gt;) are used to verify the performance of this DOP enhanced differential PA gas sensor, and the volume fraction of the sensitivity is found to be 7.25 × 10&lt;sup&gt;–7&lt;/sup&gt; for CO&lt;sub&gt;2&lt;/sub&gt;, 1.84 × 10&lt;sup&gt;–6&lt;/sup&gt; for C&lt;sub&gt;2&lt;/sub&gt;H&lt;sub&gt;2&lt;/sub&gt;, and 1.43 × 10&lt;sup&gt;–6&lt;/sup&gt; for NH&lt;sub&gt;3&lt;/sub&gt; at standard temperature and pressure, which is an order of magnitude higher than the original single mode PA value. Linear PA amplitude responses ranging from 0 to 3 × 10&lt;sup&gt;–3&lt;/sup&gt; in volume fraction with respect to the three target gases are observed, and the correction coefficients are all greater than 0.995. The DOP enhanced differential PA detection mode compensates for the weakness of the limited sensitivity associated with broadband spectroscopic methods based on blackbody radiator. Thus, the broadband DOP enhanced differential photoacoustic modality is demonstrated to be an effective approach to simultaneous, highly sensitive and selective detection of multiple trace gases.