Continuous Range Research Articles

A Widely and Continuously Tunable Single-Mode Transmitter Based on a Hybrid Microcavity Laser

A method for achieving the single-mode and efficient unidirectional emission of a whispering gallery mode (WGM) semiconductor laser is presented herein. Hybrid square-rectangular lasers (HSRLs) and hybrid square/rhombus-rectangular lasers (HSRRLs) consisting of a Fabry–Pérot (FP) cavity and a square or rhombus cavity microcavity are described. In addition, a transmitter optical subassembly (TOSA) based on an HSRRL chip was fabricated, which has a wide and continuous wavelength tuning range. Wavelength channels from 1555.75 nm to 1568.15 nm with a spacing of 50 GHz were demonstrated with a good side mode suppression ratio (SMSR) and good output power. These devices have the potential to meet the typical requirements of optical communication networks.

Wavelength-Switchable 2 μm Single-Longitudinal-Mode Thulium-Doped Fiber Laser Based on Dual-Active Cavity and DLTCTR

A thulium-doped fiber laser (TDFL) with a dual-active cavity and a directly linked three-coupler triple-ring filter is designed and demonstrated. Its operational principle is analyzed, and a corresponding experimental setup is built. Eleven single-wavelength laser outputs with a single-longitudinal-mode (SLM) output near 2 μm are obtained. The laser output covers a wavelength range from 1933.95 nm to 1971.76 nm, with a continuous switchable output range of 37.81 nm and a minimum center wavelength interval of 0.22 nm. The optical signal-to-noise ratio (OSNR) of the output laser within the tuning range is >48.53 dB, and its maximum OSNR is 70.24 dB. The minimum wavelength fluctuation is 0.03 nm, and the power fluctuation is between 0.15 and 2.61 dB. A single wavelength with a center wavelength of 1933.95 nm is monitored for 75 min, and the radio-frequency spectrum is scanned 27 times within the frequency range of 0 to 400 MHz. The results demonstrate that the TDFL can operate continuously and stably in an SLM state. The linewidth and linewidth fluctuation of the TDFL are measured, and the minimum linewidth, corresponding to a measurement time of 0.001 s, is 65.14 kHz. The experimental results show that the proposed TDFL has a high OSNR and excellent wavelength-switching ability, and its SLM operation is very stable.

Monopoly and Quality Omission

This study delves into a market characterized by vertical product differentiation. Product qualities are represented on a one-dimensional interval scale. The research investigates the equilibrium within a monopoly scenario, considering a production cost that is strictly convex. The monopoly offers a strategy comprising various quality–price combinations, with consumer choices determining profits. The analysis involves a comparison between two analogous models: one with a continuous range of consumers and the other with a finite number of consumers. The study explores disparities in the potential for market failure between these two settings. Notably, numerical illustrations underscore these divergences in both market contexts.

A framework for rapid seismic performance and fragility analysis of earth slopes considering uncertainties

It is acknowledged that various sources of uncertainties play a vital role in the seismic vulnerability of slope systems, while many studies ignore these sources in seismic assessments. This is because seismic performance and fragility evaluation of large soil-structure systems is challenging and computationally intensive by conventional nonlinear dynamic analysis methods, especially when the modeling uncertainties are considered. To address this challenge, this paper proposes a new framework for addressing uncertainties in the seismic evaluation of earth slopes using the Endurance Time Analysis (ETA) method. The ETA method is a dynamic pushover procedure in which the slope is subjected to a limited number of artificial intensifying records, and seismic responses are obtained over a continuous range of seismic intensities. For the purpose of this study, probabilistic two-dimensional numerical simulations of earth slopes are created using the FLAC software by considering the soil parameters uncertainty. Latine Hypercube Sampling is employed to generate random simulations. The models are then subjected to the intensifying prefabricated excitations based on the ETA method, and the fragility curves of the slope are obtained in three damage states by considering and not considering uncertainties. The results indicate that as the endurance time, which is a kind of intensity measure, increases, the uncertainties of seismic responses also increase. This shows that the effects of uncertainties become more significant when the slope is subjected to strong ground motions. Additionally, the influence of modeling uncertainty is negligible in the slight damage state, but significant in the extensive damage state. The proposed framework provides an effective and rapid way for performing the fragility and associated risk analysis of earth slopes considering uncertainties.

Three-dimensional computer holography with phase space tailoring

Computer holography is a prominent technique for reconstructing customized three-dimensional (3D) diffraction fields. However, the quality of optical reconstruction remains a fundamental challenge in 3D computer holography, especially for the 3D diffraction fields with physically continuous and extensive depth range. Here, we propose a 3D computer-generated hologram (CGH) optimization framework with phase space tailoring. Based on phase space analysis of the space and frequency properties in both lateral and axial directions, the intensity of the 3D diffraction field is adequately sampled across a large depth range. This sampling ensures the reconstructed intensity distribution to be comprehensively constrained with physical consistency. A physics-informed loss function is constructed based on the phase space tailoring to optimize the CGH with suppression of vortex stagnation. Numerical and optical experiments demonstrate the proposed method significantly enhances the 3D optical reconstructions with suppressed speckle noise across a continuous and extensive depth range.

Recycled crystal population proving complex plumbing systems: an archetypal example from Cretaceous alkaline magmatism in SE Brazil

Porphyritic alkaline dykes from the Serra do Mar province (SE Brazil) carry clinopyroxene macrocrysts with a complex magmatic history. Clinopyroxene is the main macrocryst phase from the Bom Repouso dyke, representing different populations. Based on petrographical features, mineral chemistry and equilibrium relationships, the clinopyroxene populations are classified as antecrysts (green cores and colourless cores and mantles) and phenocrysts (Ti-augite mantle/rims). Calculated compositions for the liquid in equilibrium with the macrocryst cores indicate mafic (colourless cores) and felsic (green cores) alkaline melts. These were used as poles for mixing-model curves, revealing a hybrid origin for the host matrix. Clinopyroxene barometry reveals key insights into the plumbing systems of the Serra do Mar province, with the Bom Repouso dyke as an archetypal example of these transcrustal systems. All target bodies record a crystallization history over a continuous range of pressures (>8 kbar up to the surface). Some preferred levels for magma storage are observed: c. 0–0.5, 1–2.5, 3–4 and 5.5–7 kbar. Our work highlights the complex magmatic history of the Serra do Mar alkaline occurrences, encompassing several open-system effects. A thorough petrographical examination is necessary to enhance our comprehension of these magmas, while petrogenetic models based on whole-rock compositions may lead to biased interpretations.

Rationalising spin relaxation during slice-selective refocusing pulses

Slice-selective refocusing pulses are powerful building blocks in contemporary magnetic resonance experiments, but their use in quantitative applications is complicated by the site-dependent signal loss they introduce. One source of this attenuation is the spin relaxation that occurs during such pulses, which causes losses that depend on the specific longitudinal and transverse relaxation time constants for a given resonance. This dependence is complicated both by any amplitude shaping of the radiofrequency pulse, and by the presence of the spatial encoding pulsed field gradient. The latter causes the net signal measured to be the weighted sum of signal contributions from a continuous range of offsets from resonance. In general, each offset will make a different contribution to the overall signal, and will be attenuated by a different mixture of longitudinal and transverse relaxation that is dictated by the different trajectories that the nuclear magnetisations take during experiments. Despite this complex behaviour, we present evidence from experiments and numerical simulations showing that in practical experimental applications a relatively simple empirical function can be used to accurately predict relaxational attenuation during slice-selective refocusing pulses. This approach may be of practical use in correcting for relaxational losses in quantitative applications of slice-selective pulse methods such as Zangger–Sterk pure shift NMR.

Microhabitat preferences in the European green lizard (Lacerta viridis): implications for conservation management of isolated populations

The European green lizard (Lacerta viridis) populations in Bohemia, Czech Republic, are isolated by more than 150 km from the northern border of the continuous range of the species. These populations are fragmented and further isolated from each other. In this landscape mosaic, they are tied to specific habitats located in deeply incised river valleys (the so-called river phenomenon) and thus may be viewed as stenotopic. The research site is located on the northern edge of the city of Prague. Since 1998, this site has been the subject of long-term conservation management aimed at strengthening and maintaining the abundance of the local L. viridis population. To formulate recommendations for the management of other isolated L. viridis populations, we performed a spatial analysis of the localities with observed individuals to determine and evaluate the significance of the chosen biotic and abiotic factors for habitat discrimination. We applied principal components and discriminant function analyses and examined the effect of 24 variables on the species’ presence. The results revealed the principal role of the presence of rock debris and hiding places for lizard occurrence. The strongest negative predictors were the presence of tall grass and high vegetation coverage. We discuss the applicability of our findings in both the theory and practice of species conservation and population management.

Efficient and widely tunable mid-infrared sources using GaAs and AlGaAs integrated platforms for second-order frequency conversion

Integrated coherent mid-infrared (mid-IR) sources are crucial for spectroscopy and quantum frequency conversion (QFC) to facilitate scalable fiber-based application of single photons. Direct mid-IR emission with broad tunability poses fundamental challenges from the gain media and mirror components. This paper presents a characterization of a second-order nonlinear platform. It showcases a mid-IR parametric coherent source with a continuous tuning range exceeding 230 nm centered around 2425 nm, achieved through difference-frequency generation (DFG). The nonlinear coefficient d14 of gallium arsenide (GaAs) and aluminum gallium arsenide (AlGaAs) on insulator is experimentally determined via second-harmonic generation (SHG) in waveguides of various lengths, and the tolerance of the process is investigated. These materials are explored for their high conversion efficiency, utilizing monolithic epitaxial quantum dots and integrated waveguides for QFC. The results demonstrate efficient and tunable mid-IR emission suitable for compact, scalable quantum emitters, with applications in environmental and health monitoring.

Flow-based Generative Emulation of Grids of Stellar Evolutionary Models

We present a flow-based generative approach to emulate grids of stellar evolutionary models. By interpreting the input parameters and output properties of these models as multidimensional probability distributions, we train conditional normalizing flows to learn and predict the complex relationships between grid inputs and outputs in the form of conditional joint distributions. Leveraging the expressive power and versatility of these flows, we showcase their ability to emulate a variety of evolutionary tracks and isochrones across a continuous range of input parameters. In addition, we describe a simple Bayesian approach for estimating stellar parameters using these flows and demonstrate its application to asteroseismic data sets of red giants observed by the Kepler mission. By applying this approach to red giants in open clusters NGC 6791 and NGC 6819, we illustrate how large age uncertainties can arise when fitting only to global asteroseismic and spectroscopic parameters without prior information on initial helium abundances and mixing length parameter values. We also conduct inference using the flow at a large scale by determining revised estimates of masses and radii for 15,388 field red giants. These estimates show improved agreement with results from existing grid-based modeling, reveal distinct population-level features in the red clump, and suggest that the masses of Kepler red giants previously determined using the corrected asteroseismic scaling relations have been overestimated by 5%–10%.

Enhanced mechanical and damping properties of Cu-Modified Al-Ni eutectic alloys: Solid-solution and precipitation hardening effects

The study aimed to analyze the mechanical properties, precipitation strengthening, and microstructure of Al-Ni-Cu alloys to understand their enhanced characteristics. Additionally, the damping behavior was examined using a dynamic mechanical analyzer across a continuous heating temperature range with frequencies from 0.5 to 15 Hz. The experimental results indicate that the Al-Ni eutectic alloy, which exhibits an ultrafine Al3Ni intermetallic fiber-reinforced Al matrix, transitions to a dendritic-ultrafine eutectic composite structure. The Cu-containing alloys exhibit two distinct primary phases: α-Al and Al-Ni-Cu ternary intermetallic compounds. The eutectic matrix transforms from Al-Al3Ni to Al-Al7Cu4Ni, and subsequently to Al-Al2Cu. These microstructural evolutions result in an enhancement of the tensile yield strength from 170 MPa to 440 MPa, with additional hardening achieved through aging-induced precipitation. Moreover, the damping capacity improves with the addition of Cu at elevated temperatures, and there is an increase in frequency dependence. This paper will discuss the microstructural features, mechanical properties, deformation behaviors, and damping properties in detail.

Research on sensing characteristics of high Q-factor all-dielectric metasurfaces based on geometric breaking

The bound states in the continuum (BIC) are widely used in designing metamaterials with high quality factor (Q-factor) resonances due to their perfect localization in the continuous spectral range coexisting with expanding waves. In this study, a T-shaped nanohole all-dielectric metasurface structure is proposed based on the unique electromagnetic properties of all-dielectric metasurfaces, and the fundamental reason of its coupled state and the theoretical basis of BIC excitation are deeply investigated based on the theory of group theory, and the geometric symmetry is broken from multiple angles, and the coupling relationship between discrete eigenmodes and the external continuum is specifically analyzed during the change of symmetry, its spectral response and near-field distribution are numerically calculated. In addition, based on the modulation mechanism of the incident light polarization angle, the three-channel resonance tuning with two resonances of the same frequency and one of a different frequency is realized under the condition that the resonance position and the Q-factor are not affected. This study not only provides a theoretical basis for the excitation conditions and evolution regularity of symmetry-protected BIC, but also solves the problem in the traditional analysis of resonance phenomena without taking the high Q-factor and stability into account, which can provide new designing methods for optical metasurface devices with multi-channel resonance.

CSQUiD: an index and non-probability framework for constrained skyline query processing over uncertain data

Uncertainty of data, the degree to which data are inaccurate, imprecise, untrusted, and undetermined, is inherent in many contemporary database applications, and numerous research endeavours have been devoted to efficiently answer skyline queries over uncertain data. The literature discussed two different methods that could be used to handle the data uncertainty in which objects having continuous range values. The first method employs a probability-based approach, while the second assumes that the uncertain values are represented by their median values. Nevertheless, neither of these methods seem to be suitable for the modern high-dimensional uncertain databases due to the following reasons. The first method requires an intensive probability calculations while the second is impractical. Therefore, this work introduces an index, non-probability framework named Constrained Skyline Query processing on Uncertain Data (CSQUiD) aiming at reducing the computational time in processing constrained skyline queries over uncertain high-dimensional data. Given a collection of objects with uncertain data, the CSQUiD framework constructs the minimum bounding rectangles (MBRs) by employing the X-tree indexing structure. Instead of scanning the whole collection of objects, only objects within the dominant MBRs are analyzed in determining the final skylines. In addition, CSQUiD makes use of the Fuzzification approach where the exact value of each continuous range value of those dominant MBRs’ objects is identified. The proposed CSQUiD framework is validated using real and synthetic data sets through extensive experimentations. Based on the performance analysis conducted, by varying the sizes of the constrained query, the CSQUiD framework outperformed the most recent methods (CIS algorithm and SkyQUD-T framework) with an average improvement of 44.07% and 57.15% with regards to the number of pairwise comparisons, while the average improvement of CPU processing time over CIS and SkyQUD-T stood at 27.17% and 18.62%, respectively.

Designing sparse extended nested arrays with high degrees of freedom and low coupling

The coupling effect significantly impacts Direction of Arrival (DOA) estimation. Employing coupling models to reduce this impact can be costly and sensitive to model fitting. Sparse arrays offer an effective means to mitigate coupling errors. Classical nested arrays in sparse arrays harbor numerous closely spaced sensor pairs, resulting in significant coupling errors. Traditional sparse arrays struggle to synchronize freedom degrees with coupling optimizations. Addressing these issues, this paper introduces Sparse Extended Nested Arrays (SENA). Comprising five subarrays, SENA effectively minimizes inter-element coupling by constraining sensor spacing within and between subarrays, maintaining freedom degrees. The paper derives and proves physical structure, continuous range of difference coarrays, and optimal choices for sensor count for SENA. Compared to traditional and improved sparse arrays with the same sensor count, SENA ensures higher freedom degrees with lower coupling errors, a superiority validated through experimental simulations.

An experimental study on the wettability of nanofluids

The wettability of nanofluid is a key factor affecting oil recovery and fluid heat transfer. However, the traditional wettability measurement method consisting in determining the contact angle enables to assess the wettability at a solid–liquid contact point only and not within the continuous detection range. Therefore, in this work, a lateral friction detection system is used to continuously measure the wettability of hydroxylated multi-walled carbon nanotubes/deionized water (MWCNT-OH/DIW) nanofluids on polydimethylsiloxane surfaces. Specifically, MWCNT-OH/DIW nanofluids with various mass fractions are configured, and different surfactants are introduced to regulate the dispersion in deionized water. The results reveal that the surface tension and contact angle decrease simultaneously with the increase in MWCNT-OH/DIW mass fraction. Meanwhile, this change also causes an increase in the lateral friction at the nanofluid/PDMS interface. Furthermore, both sodium dodecyl sulfate and cetyltrimethylammonium bromide (CTAB) as surfactants can effectively reduce its surface tension. Notably, when CTAB is added, the maximum static friction (132.62 μN) exceeds that of SDS (113.13 μN). Therefore, the proposed method opens up new prospects in wettability detection of nanofluids.

Wavelength-tunable mode-locked fiber laser based on a bending strain-controlled filter

Wavelength-tunable mode-locked fiber lasers are highly versatile and find applications in pump–probe measurement, optical communications, optical parametric oscillation, among others. Herein, we introduce a novel approach for tuning carbon nanotube-based passively mode-locked fiber laser using a bending-based mechanism. Our method involves a bending strain controlled multimode interference all-fiber filter. This filter consists of a hybrid structure built from a cascaded seven-core fiber (SCF)-twin-hole twin-core fiber (THDCF)-SCF. It achieves a continuous wavelength tuning range of 25 nm from 1558 nm to 1583 nm with a tuning efficiency of −3.38 nm/m−1. By increasing the pump power, the dual-wavelength locked modes are also achieved at specific curvature. Owing to advantages of simple structure, low cost, and high bending sensitivity, our tunable filter shows promise for efficient wavelength tuning in ultrafast fiber laser.

Design of near-infrared solid-state tunable Fabry-Perot filters based on VO2/P4VP films

The significant refractive index change of VO2 during phase transition makes it attractive for the design of optical switches and filters, but high absorption of VO2 limits its development in the field of filter. In this paper, we firstly design near-infrared solid-state tunable/switchable single-/dual-band bandpass Fabry-Perot (F-P) filters based on VO2/P4VP composite films using COMSOL software. The simulation results show that the single-passband tunable filter can achieve a continuous thermal tuning range of 19 nm at 1064 nm, the full width at half maxima (FWHM) is 28.8 nm, and the peak transmittance is >30%. On this basis, we simulated a tunable dual-band bandpass filter, the left peak can be heated to achieve a tuning range of 15 nm (945 nm), the right peak is 24 nm (1168 nm), the peak transmittances of both the two peaks are >35%. When boosting the VO2 fraction, the continuous tunability of the above-mentioned single-/dual-band filters will be switchable due to the high absorption of VO2, and then switchable single-/dual-band bandpass filters are designed. This work has guiding significance for the design of novel filter structures and optical tunable devices based on phase change materials such as VO2 in the future.

Incorrectly Focused Neodymium:Yttrium-Aluminum-Garnet (Nd:YAG) Laser Beam Leads to Massive Destructive Effects in Small-Aperture (Pinhole) Intraocular Lenses.

Pinhole intraocular lenses (IOLs) were developed to improve reading by compensating for loss of accommodative function. The IC-8® Apthera™ is a small-aperture presbyopia-correcting IOL that combines the proven principle of small-aperture optics with an aspheric monofocal lens to deliver a continuous range of vision for patients withcataractsfrom distance to near vision. Posterior capsule opacification is the most common sequela after cataract surgery. It is effectively treated by laser capsulotomy. However, if the laser beam is incorrectly focused, the IOL can be permanently damaged (pits/shots). In this experimental study, yttrium-aluminum-garnet (YAG) pits were purposefully created. Defects were analyzed and compared between the periphery of the ring in the clear area of the hydrophobic acrylic lens and at the carbon black (CB)-polyvinylidene fluoride (PVDF) filtering component (FilterRing™) of the pinhole lens. All defects were made using identical settings/energy levels (2.6mJ). The damage induced to the IC-8® Apthera™ IOL was examined by low-magnification images, light microscopy, scanning electron microscopy, and micro-computed tomography (micro-CT). YAG defects in the carbon black filter ring were much more severe than those in the clear zone due to the high absorption of the carbon black. Massive defects and destruction of the lens with tearing out of fragments and particles were observed. The missing volume calculated from the micro-CT reconstruction was 0.266 mm3, which is 1.6% of the entire IOL volume, or more than 1000 times the volume damaged in the largest shot in the periphery. Based on the results, we highly recommend using the lowest possible energy levels, posterior offset setting, and circular pattern for maximum safety when performing laser capsulotomy with pinhole implants. Care should be taken to avoid creating irreversible iatrogenic defects that may affect overall quality. The safest area for performing capsulotomy seems to be the periphery of the ring segment. Video available for this article.

Enhancing low-temperature lithium-ion battery performance under high-rate conditions with niobium oxides

Low-temperature operation (−20 °C and below) under high-rate conditions is a critical deficiency for lithium-ion batteries. To achieve size, weight, and power requirements tailored for demanding applications, novel materials are needed to sustain high performance. In the present study, we synthesize a series of niobate anode materials (Nb2O5, Nb2O5–x, and Nb12O29) and tailor their particle size, defect nature, and electrical/ionic conductivity to enable high-performance operation at −20 °C under high-rate conditions (1.2C–2C). When paired with lithium manganese oxide (LMO) in a full-cell configuration, the Nb2O5–x-based full-cells achieve high-rate capability (∼90 mAh/g up to 2C cycling rate at −20 °C) and great long-term stability (>98% retention up to 50 cycles at −20 °C). During a simulated 30 min duty cycling test synthesized from measured data from an actual drone flight (continuous range of 1.2C–2C cycling rates), the Nb2O5–x||LMO cell enables full discharge at −20 °C, with only a 0.3 V voltage drop when compared to duty cycling at room temperature. The work presented herein demonstrates the future possibilities of expanding the operational capabilities of lithium-ion batteries.

Consonance in the carillon.

Previous psychological studies have shown that musical consonance is not only determined by the frequency ratios between tones, but also by the frequency spectra of those tones. However, these prior studies used artificial tones, specifically tones built from a small number of pure tones, which do not match the acoustic complexity of real musical instruments. The present experiment therefore investigates tones recorded from a real musical instrument, the Westerkerk Carillon, conducting a "dense rating" experiment where participants (N = 113) rated musical intervals drawn from the continuous range 0-15 semitones. Results show that the traditional consonances of the major third and the minor sixth become dissonances in the carillon and that small intervals (in particular 0.5-2.5 semitones) also become particularly dissonant. Computational modelling shows that these effects are primarily caused by interference between partials (e.g., beating), but that preference for harmonicity is also necessary to produce an accurate overall account of participants' preferences. The results support musicians' writings about the carillon and contribute to ongoing debates about the psychological mechanisms underpinning consonance perception, in particular disputing the recent claim that interference is largely irrelevant to consonance perception.