Multimode System Research Articles

Enhanced mechanical squeezing in an optomechanical system via backward stimulated Brillouin scattering

Abstract We investigate theoretically the enhancement of mechanical squeezing in a multimode optomechanical system by introducing a coherent phonon-photon interaction via the backward stimulated Brillouin scattering (BSBS) process. The coherent photon-phonon interaction where two optical modes couple to a Brillouin acoustic mode with a large decay rate provides an extra channel for the cooling of a Duffing mechanical oscillator. The squeezing degree and the robustness to the thermal noises of the Duffing mechanical mode can be enhanced greatly. When the Duffing nonlinearity is weak, the squeezing degree of the mechanical mode in the presence of BSBS can be improved more than one order of magnitude compared with the absence of BSBS. Our scheme may be extended to other quantum systems to study novel quantum effects

Design theory for section model tests considering multimode coupling and imperfect modeshape similarity of full bridges

Section model tests are the most fundamental wind-tunnel technique widely employed in the design of flexible cable-supported bridges. To guarantee the accuracy of aeroelastic stability assessment, the dynamic behavior of a section model test should reflect the aeroelastic characteristics of the full bridge. Conventional method only employs the fundamental vertical and torsional modes for the design of dynamic parameters, typically ignoring multimode coupling effect and assuming perfect modeshape similarity. This paper introduces a novel theoretical framework that integrates multimode coupling and imperfect modeshape similarity into the design of a section model test. The framework establishes a direct equivalence between the complex modal parameters of the unstable mode in the multimode coupling system and the two degrees-of-freedom coupling system of the section model. It quantifies each mode's contribution to coupled flutter through a single parameter denoted as mode participation factor. Validation of this improved design theory is performed using numerical models of four representative cable-supported bridges, highlighting its effectiveness. The study also sheds light on the complexities of multimode aeroelastic coupling and the limitations of section model tests.

Nonreciprocal Photon Transport in a Chiral Optomechanical System

AbstractChiral interaction between light and quantum emitters leads to emergence development of chiral quantum optics and stimulates a wide range of practical applications in quantum regime, such as single‐photon isolation and photon unidirectional emission. Cavity optomechanics studying the interaction between optical and mechanical resonators plays an important role in the field of quantum optics. However, how to achieve the chiral interaction between light and mechanical oscillators and explore the applications of the chiral optomechanical systems are still difficult encountered in cavity optomechanics. Here, a method is proposed to achieve chiral optomechanical interaction by exploiting directional squeezed light in a multimode optomechanical system. Based on the chiral interaction between photon and phonon, the nonreciprocal photon transport at a single‐photon level can be realized. An isolation ratio of and a negligible insertion loss for the photonic isolator are obtained. This method paves the way to realize chiral optomechanical interaction for conducting chiral optomechanics and opens up the prospect of exploring and utilizing chiral photon–phonon manipulation in the quantum regime.

Improving the catchment area identification for suburban railway stations by incorporating whole-journey-based mode choices and unevenly distributed population

Suburban railways have emerged as a predominant transport mode for suburbanization development in megacities. Enhancing transit-oriented development (TOD) in the catchment area of suburban railway stations is an essential strategy. To improve the catchment area identification, we proposed a method for delineating the catchment areas of suburban railway stations from the whole journey perspective and under a multi-mode access travel system. The grey distance delay (GDD) model was constructed to determine the catchment area. A case study was used to illustrate the applicability and advantages of our proposed method in metropolitan areas worldwide. The results indicated that the acceptable access distances vary greatly across access travel modes and are affected by the main travel in the suburban railway at the same time. The range of the catchment areas of bicycle and bus is larger than that of urban rail transit, and the strength of attraction of bicycle and bus shows a trend of increasing at first and then decreasing. Each access travel mode has its competitive advantage area, and these travel modes jointly serve the access trip within the suburban rail catchment area through a competition and cooperation relationship. These findings are able to enhance the identification of the catchment area and provide insights for suburban TOD and transport planning.

A Multimode Fusion-Based Aviation Communication System

This paper presents a new design for a multimode fusion communication system, aimed at tackling the complexities of modern aeronautical communication. The system integrates multiple communication technologies, such as ad hoc networking, 5G, BeiDou satellite, RTK positioning, and ADS-B broadcasting. This integration effectively solves the problem of increasing the size and weight of aviation communication equipment while also improving the efficiency and security of data communication. The study demonstrates that the implementation of this fusion communication system can lead to the development of more efficient and intelligent avionics equipment in the future, thereby offering robust technical support for flight safety.

Slow light in loop-coupled multimode optomechanical system

We theoretically propose a loop-coupled multimode optomechanical system (OMS) with a single-mode cavity, a two-level system (TLS), and a mechanical resonator, which are coupled to each other. With controlled coupling parameters, the loop-coupled multimode OMS can flexibly transform into different OMSs (e.g. cavity OMSs, cavity quantum electrodynamic systems). By simultaneously driving the single-mode cavity using pump and probe fields, we investigate the coherent optical response and transmission spectra for the transparent window and absorption dips. Additionally, the transparent window and absorption dips that induce coherent light propagation were demonstrated. Our findings demonstrate that the transparent window and absorption dips can generate slow (fast) light, and that the control of coupling parameters can modulate optical fields in different OMSs. With further weaving of these coupling parameters, the loop-coupled multimode OMS can be a quantum information processing platform for chip-scale applications.

Research on fault diagnosis of multi-mode electromechanical compound transmission system for hybrid electric vehicle based on global analytical redundancy relations

In order to effectively monitor the operational status and detect faults within a hybrid electric vehicle during mode transitions, this study focuses on a specific power-split hybrid electric vehicle model known as the multimode electromechanical composite transmission system (MM-EMCTS HEV). Taking into account the actual occurrence frequency and simulatability of faults in MM-EMCTS HEV, key faults are extracted. Based on the distinctive characteristics and properties of critical system faults, a fault diagnosis framework is constructed by leveraging global analytical redundancy relations (GARRs). This framework encompasses strategies for residual generation across sensors, actuators, and controlled components, alongside residual evaluation techniques employing mode-dependent adaptive thresholds. The detectability and isolatability of the MM-EMCTS are thoroughly analyzed. Subsequently, simulation and verification of the residual responses under typical faults in the MM-EMCTS are implemented in Matlab/Simulink and Simscape. The results demonstrate the efficacy of the fault diagnosis method, rooted in global analytical redundancy relations and mode-dependent adaptive thresholds, in successfully detecting and isolating faults within multimode electromechanical composite transmission systems. Furthermore, compared to conventional fixed threshold residual evaluation approaches, this method significantly mitigates the occurrence of missed detections, thus verifying the effectiveness and superiority of the proposed method.

Enhancing the efficiency of chemical vapor generation of zinc in a multimode sample introduction system

Enhancing the efficiency of chemical vapor generation of zinc in a multimode sample introduction system

Proximity-encirclement of exceptional points in a multimode optomechanical system

Dynamic encirclement of second-order exceptional points (EPs) exhibits chiral state transfer; however, investigations into the dynamics involving multiple and higher-order EPs remain sparse. Here, we study the proximity-encirclement of EPs within a multimode optomechanical system to elucidate the closed-path evolution in high-order non-Hermitian systems. Our optomechanical framework presents three distinct EP scenarios: absence of EPs, presence of a pair of second-order EPs, and the existence of a third-order EP. We meticulously analyze the system’s dynamic behavior, considering variables such as initial state, loop orientation and velocity, loop starting point variance, and the number and order of encircled EPs during state transfer processes. The findings reveal that chiral or non-reciprocal state transfer can be achieved when a loop encircles a second-order EP with varying radii. Encircling two second-order EPs results exclusively in chiral state transfer. Furthermore, both chiral and non-reciprocal state transfers are observed within a single loop encircling a third-order EP. These phenomena in the context of multimode optomechanical systems provide a new approach for manipulating state transfer in higher-order non-Hermitian systems.

Spatial accessibility and equity of community healthcare: unraveling the impact of varying time and transport mode.

Achieving a higher level of accessibility and equity to community healthcare services has become a major concern for health service delivery from the perspectives of health planners and policy makers in China. In this study, we introduced a comprehensive door-to-door (D2D) model, integrating it with the open OD API results for precise computation of accessibility to community hospitals over different transport modes. For the D2D public transit mode, we computed the temporal variation and standard deviation of accessibility at different times of the day. Additionally, accessibility values for D2D riding mode, D2D driving mode, and simple driving mode were also computed for comparison. Moreover, we introduced Lorenz curve and Gini index to assess the differences in equity of community healthcare across different times and transport modes. The D2D public transit mode exhibits noticeable fluctuations in accessibility and equity based on the time of day. Accessibility and equity were notably influenced by traffic flow between 8 AM and 11 AM, while during the period from 12 PM to 10 PM, the open hours of community hospitals became a more significant determinant in Nanjing. The moments with the most equitable and inequitable overall spatial layouts were 10 AM and 10 PM, respectively. Among the four transport modes, the traditional simple driving mode exhibited the smallest equity index, with a Gini value of only 0.243. In contrast, the D2D riding mode, while widely preferred for accessing community healthcare services, had the highest Gini value, reaching 0.472. The proposed method combined the D2D model with the open OD API results is effective for accessibility computation of real transport modes. Spatial accessibility and equity of community healthcare experience significant fluctuations influenced by time variations. The transportation mode is also a significant factor affecting accessibility and equity level. These results are helpful to both planners and scholars that aim to build comprehensive spatial accessibility and equity models and optimize the location of public service facilities from the perspective of different temporal scales and a multi-mode transport system.

Monitoring of three-dimensional live-cell cultures using a multimode, multiscale imaging system combining confocal fluorescence microscopy and optical coherence microscopy

Live-cell monitoring involves long-term observation and analysis of living cells in tissue cultures, which develop cells or tissues in an artificial environment and are essential for tissue engineering. Fluorescence microscopy (FM) is widely used as a monitoring tool owing to its powerful ability to visualize protein distribution within cells and tissues, thereby providing information on their functions in biological processes. To reduce the photobleaching effect, which is a major limiting factor in FM, FM is generally combined with other imaging modalities, such as phase contrast and differential interference contrast microscopy, which are nondestructive to fluorochromes, to selectively use fluorescence signals only in specific areas of interest within a sample. However, these methods are restricted to thin samples and cannot produce depth-resolved images. Here, we propose a method to determine three-dimensional (3D) positions in volumetric samples for application in high-resolution 3D fluorescence imaging using a multimode and multiscale imaging system that combines optical coherence microscopy (OCM) and line confocal FM (LC–FM). We also demonstrate the benefits of multimodal imaging in 3D cell culture monitoring. To evaluate the performance of the proposed system and method, we rapidly and accurately located the regions of interest in 3D tissue culture models, such as tumor spheroids and microvascular bed, and instantaneously acquired volumetric high-resolution fluorescence images. We also used an integrated system to monitor tumor spheroids mixed with extracellular matrix (ECM) over five days of the culture process, and the FM–OCM integrated technique successfully imaged the overall 3D structures, such as the distribution and boundaries of the spheroids and ECM as well as stained tumor cells. This complementary information is useful for understanding the relationship between cellular behaviors, such as the proliferation and migration of tumor cells, and microenvironments, such as the ECM.

MoSe2-based magnetic nanosystem for clinical enrichment, retrieval and elimination of circulating tumor cells

The detection, analysis and clearing of circulating tumor cells (CTCs) from patients’ bloodstream at an early stage are important to diagnose the primary tumor progression and decrease cancer metastasis-related mortality. Herein, we developed a molybdenum diselenide nanosheet (MoSe2 NS) based magnetic nanosystem, which was surface functionalized with the anti-epithelial cell adhesion molecule (anti-EpCAM) antibody. CTCs were successfully isolated by the magnetic nanosystem from blood samples of clinical cancer patients. Highly efficient CTCs enrichment was achieved when the nanosystem was applied with a concentration down to 25 µg ml−1 in both static and biomimetic circulating conditions. The nanosystem was demonstrated biocompatible without obvious cytotoxicity, allowing in vitro culture of the captured cells for downstream analysis. Further, the magnetic nanosystem presented a reinforced photothermal effect due to the integration of several photothermal agents including MoSe2 NS, ferroferric oxide (Fe3O4) nanoparticles, and polydopamine (pDA), allowing fast in-situ elimination of the captured cells under NIR laser (808 nm) irradiation. This work represents a multimode system that enables highly efficient enrichment of rare CTCs from patients’ blood for either retrieval or clearing, with great promise for early cancer diagnosis and possible treatment screening.

Working mode division and shift schedule extraction of a parallel hybrid power system

Abstract For hybrid electric vehicles, working mode division and shift schedule are two decisive factors affecting vehicle fuel economy. This paper introduces a method for vehicle working mode division and shift schedule determination on the basis of optimal system efficiency. The key index named ‘fuel-electricity conversion efficiency’ is defined and calculated. Via this method, unreasonable gear modes in specific working modes are excluded and the mode transition map and upshifting curves in each working mode are extracted. The simulation results demonstrate that, with the application of the single-motor multi-mode parallel hybrid power system, the proposed mode transition and shifting strategy can increase vehicle fuel economy by 12.99%.

Single wavelength MDM-PDM 800-Gb/s net data rate transmission over a standard multimode fiber employing a Kramers-Kronig receiver.

We propose a high-speed multimode fiber short-reach optical interconnect system based on a Kramers-Kronig (KK) field reconstruction with the mode division multiplexing (MDM) and polarization division multiplexing (PDM) technology. In this work, the LP01, LP21a, LP21b, and LP02 modes are selected as independent channels to carry information. The demonstration achieved the 800 Gb/s net data rate per wavelength with a bit-rate-distance-product (BDP) of 8 Tb/s·km. To the best of our knowledge, this is the highest experimental record of a single wavelength BDP over the SMMF with KK detection. In addition, we discuss the system performance after all multiple-input multiple-output (MIMO) and partial MIMO processing and give guidance on the trade-off between system performance and computational resource.

Development of a novel laboratory photodynamic therapy device: automated multi-mode LED system for optimum well-plate irradiation

HighlightsMulti-mode Automated Well-plate PDT LED Laboratory Irradiation System described.Automates and standardizes time-consuming experiments.LED wavelength and temperature stabilized for highly reproducible irradiations.Efficacy demonstrated in 5-aminolevulinic acid (5-ALA) treatments of HT-29 colon cancer cells and WI-38 human lung fibroblasts.

Performance analysis of a novel multimode electricity-cooling cogeneration system (ECCS) driven by exhaust from a marine engine

Multiple operating modes and flexible outputs are typical characteristics of multimode electricity-cooling cogeneration systems (ECCS). The present study proposes an innovative multimode ECCS driven by exhaust gas from marine engines and presents a corresponding thermodynamic system model. The thermodynamic performance, distribution region of operating modes, and exergoeconomic performance of the system are comprehensively investigated under various operational conditions. A novel comprehensive evaluation index, namely, the system net output per unit total mass flow rate (NOPF), is introduced to ensure that the analysis of system performance remains unaffected by the variations in the mass flow rate of the working fluid. The findings indicate that the operational modes exhibit diverse responses to influencing variables, while the distribution region of the operational modes is more sensitive to the separation ratio of the working fluid flow rate (X). Under the electricity-cooling generation mode of the system, the maximum NOPF reaches 156.01 kJ⋅kg−1. Furthermore, the proposed system achieves a peak exergy efficiency (ηex) of 13.83 %, concurrently decreasing the energy production cost (EPC) to a mere 0.0981 Dollar·kWh−1. Finally, this study offers new research insights that can inform future regional analyses of other multimodal and multigeneration systems.

A Multi-Mode SPAD-Based Ranging System Integrated Nonlinear Histogram and FIR With Adaptive Coefficient Adjustment

A Multi-Mode SPAD-Based Ranging System Integrated Nonlinear Histogram and FIR With Adaptive Coefficient Adjustment

Calorimetry of Photon Gases in Nonlinear Multimode Optical Fibers

Recent studies have shown that light propagating in a nonlinear, highly multimode system can thermalize in a manner totally analogous to that encountered in traditional statistical mechanics. At thermal equilibrium, the system’s entropy is at a maximum, in full accord with the second law of thermodynamics. In such arrangements, the entropy is extremized once the statistical power allocation among modes associated with this photon gas attains a Rayleigh-Jeans distribution that is fully characterized by an optical temperature T and a chemical potential μ. However, it has been theoretically argued that the variables T and μ represent actual thermodynamic forces that control the exchange of the respective conjugate quantities between two subsystems. In this work, we report, for the first time, optical calorimetric measurements in nonlinear multimode fibers, which unambiguously demonstrate that both the temperature T and the chemical potential μ dictate the flow of their associated extensive quantities, i.e., the energy and the optical power. Specifically, we study the process of light thermalization associated with two orthogonally polarized laser beams. Our observations are enabled by recently developed techniques that allow one to judiciously multiplex/demultiplex the optical power within various mode groups. Our results indicate that because of photon-photon collisions, “heat” only flows from a hot to a cold photon gas subsystem—thus providing an unequivocal demonstration of the second law in such all-optical thermodynamic arrangements. In addition to being fundamental, our findings provide a new approach to manipulate laser beams using thermodynamic principles. Published by the American Physical Society 2024

Lightweight super-resolution multimode fiber imaging with regularized linear regression

Super-resolution multimode fiber imaging provides the means to image samples quickly with compact and flexible setups finding many applications from biology and medicine to material science and nanolithography. Typically, fiber-based imaging systems suffer from low spatial resolution and long measurement times. State-of-the-art computational approaches can achieve fast super-resolution imaging through a multimode fiber probe but currently rely on either per-sample optimised priors or large data sets with subsequent long training and image reconstruction times. This unfortunately hinders any real-time imaging applications. Here we present an ultimately fast non-iterative algorithm for compressive image reconstruction through a multimode fiber. The proposed approach helps to avoid many constraints by determining the prior of the target distribution from a simulated set and solving the under-determined inverse matrix problem with a mathematical closed-form solution. We have demonstrated theoretical and experimental evidence for enhanced image quality and sub-diffraction spatial resolution of the multimode fiber optical system.

Multimode thermoacoustic system for heating and cooling

Thermoacoustic technology emerges as a sustainable and low-carbon method for energy conversion, leveraging environmentally friendly working mediums and independence from electricity. This study presents the development of a multimode heat-driven thermoacoustic system designed to utilize medium/low-grade heat sources for room-temperature cooling and heating. We constructed both a simulation model and an experimental prototype for a single-unit direct-coupled thermoacoustic system, exploring its performance in heating-only, cooling-only, and hybrid heating and cooling modes. Internal characteristic analysis including an examination of internal exergy loss and a distribution analysis of key parameters was first conducted in the hybrid cooling and heating mode. The results indicated a positive-focused traveling-wave-dominant acoustic field within the thermoacoustic core unit, enhancing energy conversion efficiency. The output system performance was subsequently tested under different working conditions in the heating-only and cooling-only modes. A maximum output heating power of 2.3 kW and a maximum COPh of 1.41 were observed in the heating-only mode. Meanwhile, a cooling power of 748 W and a COPc of 0.4 were obtained in the typical cooling condition at 7 °C when operating in cooling-only mode. These findings underscore the promising potential of thermoacoustic systems for efficiently utilizing medium/low-grade heat sources for cooling and/or heating applications in the future.