Single-mode Systems Research Articles

A simplified approach to assist process development for microwave assisted pasteurization of packaged food products

The purpose of this study was to develop a convenient method to assist the food industry in developing process schedules for production of ready-to-eat meals using microwave assisted pasteurization system (MAPS). An analytical model was applied to estimate the temperature increase in the cold zone in packaged foods during heating in a 915 MHz single-mode microwave system. This model was validated in a pilot-scale four-cavity MAPS using mashed potato-gellan gum model food with different thicknesses (22 to 36 mm) and salt contents (0.0 to 1.0%). Mobile sensors were placed in the packages to measure temperature at the pre-determined cold spots. For 2.48 min of microwave heating with 5, 5, and 8.7 kW 915 MHz microwave powers, the highest temperature increase at the cold spot during microwave heating was 33.2 °C in the 22 mm thick model food with 0.6% salt content, whereas the lowest temperature increase was 10.3 °C in the 36 mm thick model food with 1.0% salt content. There was a deviation of 1.9 ± 1.2 °C between experimental and predicted data with an R2 of 0.89. A simplified chart was developed based on the validated analytical results to allow rapid prediction of temperature increases in MAPS as influenced by food dielectric properties and package thickness. Examples were used to illustrate how the chart could assist in process scheduling. The chart can help assess the heating rates of various pre-packaged food products in a specific industrial MAPS or guide product development for desired heating uniformity.

Dissipative solitons in photonic molecules

Many physical systems display quantized energy states. In optics, interacting resonant cavities show a transmission spectrum with split eigenfrequencies, similar to the split energy levels that result from interacting states in bonded multi-atomic, i.e. molecular, systems. Here, we study the nonlinear dynamics of photonic diatomic molecules in linearly coupled microresonators and demonstrate that the system supports the formation of self-enforcing solitary waves when a laser is tuned across a split energy level. The output corresponds to a frequency comb (microcomb) whose characteristics in terms of power spectral distribution are unattainable in single-mode (atomic) systems. Photonic molecule microcombs are coherent, reproducible, and reach high conversion efficiency and spectral flatness whilst operated with a laser power of a few milliwatts. These properties can favor the heterogeneous integration of microcombs with semiconductor laser technology and facilitate applications in optical communications, spectroscopy and astronomy.

Research on modelling and simulation of single-mode power split hybrid system

Aiming at an optimised single-mode compound power split hybrid system, the main operating mode of the hybrid system and the torque control strategy were developed in this paper. LMS/AMESim was used to establish the plant model of the vehicle as well as the key components of the hybrid system, while the vehicle control model was established in Matlab/Simulink. In addition, the fuel economy of a certain SUV under the NEDC road spectrum was simulated by the co-simulation model, and the simulation results were compared with the experimental results on the auto chassis dynamometer. The results demonstrated that the established simulation model is an accurate reflection of the physical reality under different road spectrum conditions. Application of the model can greatly reduce the difficulty of control strategy design and improve the efficiency of vehicle development.

An Adaptive Multi-Mode Underwater Acoustic Communication System Using OSDM and Direct Sequence Spread Spectrum Modulation

Dynamic underwater acoustic network is a research hotspot. Due to the complexity and time-varying of underwater acoustic channel, the performance of single-mode underwater acoustic communication system is often limited by the worst channel situation. Orthogonal signal division multiplexing (OSDM) is a new signal modulation technology, which can be regarded as a bridge between single carrier modulation and orthogonal frequency division multiplexing (OFDM) modulation. In order to improve the channel adaptive ability of underwater acoustic communication system and obtain a unified architecture of different carrier modulation, an adaptive multi-mode underwater acoustic communication system based on OSDM and direct sequence spread spectrum modulation (AMMUAC/OS) is proposed in this paper. Combined with spread spectrum modulation, the system can realize single carrier time domain spread spectrum (SC-TDSS), single carrier system with cyclic prefix (SC-CP), OSDM, multicarrier frequency domain spread spectrum (MC-FDSS), and OFDM communication system by adjusting the vector length M of OSDM. The addition of a variety of digital mapping methods enables the system to achieve multi-mode communication with a unified architecture. Based on the relationship between the OSDM vector length M and the underwater acoustic channel delay, a joint adaptive decision criterion based on the maximum channel delay and the channel signal-to-noise ratio (SNR) is proposed. Firstly, the OSDM vector length M is determined according to the maximum channel delay, and then the system communication mode is selected according to the channel SNR. Orthogonal matching pursuit (OMP) channel estimation algorithm is used to obtain channel information and minimum mean square error (MMSE) channel equalization algorithm is used for channel compensation. An adaptive multi-mode data frame structure is designed for the interaction between the sender and the receiver. The simulation results show that the proposed AMMUAC/OS can adapt to underwater acoustic channels with different channel delay and SNR.

Research on modelling and simulation of singlemode power split hybrid system

Aiming at an optimised single-mode compound power split hybrid system, the main operating mode of the hybrid system and the torque control strategy were developed in this paper. LMS/AMESim was used...

Applications of representation transformation and secular perturbation theory to coupled Duffing equations

In physics, the non-linear mode coupling is an important strategy to manipulate the mechanical properties of a vibrational system. Compared with the single-mode nonlinear system, the complex systems with two- or multi-mode nonlinear coupling have garnered considerable attention, among which the analytical solutions to the coupled Duffing equations are widely studied to solve nonlinear coupling. The fact is that the solving of the Duffing coupling equations generally starts with the eigenmodes solution of the linear equations. The trial solution of the coupled equations is the linear superposition of the eigenmodes. Under the secular perturbation theory and similar conditions, the Duffing coupling equation degenerates into two decoupled equations. However, thus far most of the solution methodologies are too complicated to unravel the underlying physical essence clearly. In this paper, first, by applying the representational transformation to the linear terms of the first-order coupled Duffing equations and the secular perturbation theory for the nonlinear terms, a decoupled expression of the first-order Duffing equations is derived, which can be solved more straightforwardly. Subsequently, in order to verify the correctness of the method, we design a coupled tuning fork mechanical vibration system, which consists of two experimental instruments to provide driving force and receive signals, two tuning forks and springs. The amplitude spectra are measured by an experimental instrument of forced vibration and resonance (HZDH4615), which provides a periodic driving signal for the tuning fork. The numerical fitting by software is employed to clarify the mechanism of the spectrum. Theoretically, the obtained fitting parameters can also evaluate some important attributes of the system. Most strikingly, due to the nonlinear coupling the splitting of the resonant peak and the phenomenon of “hysteresis loop” are clearly observed in the experiment. The research shows that the experimental results perfectly match the theoretical results obtained before. The method of solving coupled nonlinear equations in this article provides a solution and improvement of flexible adoption of nonlinear theory. On the other hand, it can be extended to coupled light and electricity systems, offer certain guidance for understanding the dynamic behavior of coupled systems, and will be conductive to the quantitative examination of numerous nonlinear coupling devices.

Single-mode fiber auto-coupling system with wedges

Efficiently coupling Gaussian beams into single-mode fibers (SMF) plays an important role in scientific experiments. However, the optical misalignment will decrease the coupling efficiency dramatically. In this paper, we proposed and investigated a SMF auto-coupling system consisting of two wedges driven by stepper motors. We simulated and analysed the dual-wedge system’s ability of correcting optical misalignment and experimentally demonstrated the feasibility of this proposal. The results show that when the optical path is misaligned within a certain range, by automatically rotating the two wedges, the system can restore the efficiency to near the manually optimal coupling efficiency. The system inherits the stability of the stepper motors and will be beneficial for space applications and other unmanned scientific experiments.

Finite Element Modeling for Fluorescence Molecular Tomography

Non-contact Fluorescence Molecular Tomography (FMT) and Bioluminescence Tomography (BLT) has attracted more and more attention due to its unique advantages. For real experiments, how to obtain the 3D model of an object and the surface fluorescence distribution is one of the main obstacles. In this paper, an effective method to obtain the Finite Element Model is presented. We discuss the geometric and mathematical principles in detail. We prove that the FEM model generated by the method has enough quality for reconstruction. We demonstrate the quality of the model through a series of examples. This method can realize the whole process only by using a single-mode optical system. Firstly, a series of white light and fluorescence images are collected along the object in white light flat field illumination mode and excitation fluorescence mode respectively. The white light illumination images are used to reconstruct the 3D model contour of the object. After voxelization with appropriate resolution, we use the Delaunay algorithm to divide the model into tetrahedral finite elements. For the fluorescence image, we proposed a method based on vertex normal vector to realize the photon flux density mapping from 2D fluorescence image to 3D Finite Element Method (FEM) mesh nodes of the surface. The experimental results prove the accuracy of the model and the mapping, and the FEM obtained can meet the needs of FMT/ BLT reconstruction.

Yb3+ doped single-mode silica fibre laser system for high peak power applications

We present ytterbium doped silica single-mode fibre components for high power and high energy laser applications. We developed in-house the fibre laser with high efficiency of 65% according to the launched power, the threshold of 1.16W and the fibre length of 20 m. We also elaborated the fibre with 20 µm in diameter core suitable for amplifying the beam generated in oscillator. We implemented made in-house endcaps to prove the utility of the fibre towards high peak power applications. Full Text: PDF ReferencesStrategies Unlimited, The Worldwide Market for Lasers: Market Review and Forecast, 2020 DirectLink J. Zhu, P. Zhou, Y. Ma, X. Xu, and Z. Liu, "Power scaling analysis of tandem-pumped Yb-doped fiber lasers and amplifiers", Opt. Express 19, 18645 (2011) CrossRef IPG Photonics, Product information, accessed: October, 2020. DirectLink J.W. Dawson, M. J. Messerly, R. J. Beach, M. Y. Shverdin, E. A. Stappaerts, A. K. Sridharan, P. H. Pax, J. E. Heebner, C. W. Siders, and C. P. J. Barty, "Analysis of the scalability of diffraction-limited fiber lasers and amplifiers to high average power", Opt. Express 16, 13240 (2008) CrossRef W. Koechner, "Solid-State Laser Engineering", Springer Series in Optical Science, Berlin 1999 CrossRef A. V. Smith, and B. T. Do, "Bulk and surface laser damage of silica by picosecond and nanosecond pulses at 1064 nm", Appl. Opt. 47, 4812 (2008), CrossRef M. N. Zervas, C. Codemard, "High Power Fiber Lasers: A Review", IEEE J. Sel. Top. Quantum Electron. 20, 1, 2014 CrossRef D.J. Richardson, J. Nilsson, and W.A. Clarkson, "High power fiber lasers: current status and future perspectives [Invited]", J. Opt. Soc. Am. B, 27, 63, 2010, CrossRef M. Li, X. Chen, A. Liu, S. Gray, J. Wang, D. T. Walton; L. A. Zenteno, "Limit of Effective Area for Single-Mode Operation in Step-Index Large Mode Area Laser Fibers", J. Lightw. Technol., 27, 3010, 2009, CrossRef J. Limpert, S. Hofer, A. Liem, H. Zellmer, A. Tunnermann., S. Knoke, and H. Voelckel, "100-W average-power, high-energy nanosecond fiber amplifier", App.Phys.B 75, 477, 2002, CrossRef

Single-mode nonclassicality criteria via Holstein–Primakoff transformation

We study different representations of a many-particle system. We reveal the connections among the nonclassicalities of many-particle, single-mode and two-mode systems in the infinite particle number limit. First, we demonstrate that (separable) atomic coherent states, of a many-particle system, mimic the coherent states of single-mode light as the number of particles goes to infinity. This enables the utilization of a many-particle entanglement (MPE) criterion as a single-mode nonclassicality (SMNc) condition via Holstein–Primakoff transformation in this limit. As an example, we show that spin-squeezing criterion, for MPE, can be transformed into quadrature-squeezing, a nonclassicality condition for a single-mode system. Second, we demonstrate a similar connection between the two-mode separable states and separable atomic coherent states of a many-particle system for the infinite particle number limit. The second connection makes us be able to obtain an SMNc condition from a two-mode entanglement (TME) criterion, using the many-particle system as a bridge. As an example, we obtain Mandel’s Q-parameter from the TME criterion of Hillery and Zubairy.

Doubly resonant SFG and DFG spectroscopies: An analytic model for data analysis including distorted and rotated vibronic levels. II. Applications.

The influence of vibration mode distortion and mode mixing in the vibronic structure of molecules on the doubly resonant sum (SFG) and difference frequency generation spectroscopies is systematically studied in several examples. These phenomena modify the spectral overlap function at the heart of the modeling of the doubly resonant processes. When the visible beam is tuned, under the Franck-Condon approximation, each vibration mode generates two main peaks corresponding to the resonance of the molecular electronic transition with the visible and SFG energies, together with higher order ones driven by the amplitudes of the vibronic displacements. For a single mode system, mode distortion modifies the positions of the main peaks and the excitations of the higher order ones. For a two-mode system, mode mixing induces in addition a deep change in the balance between the intensities of the mixed modes. It also changes the phases of the vibrations, which makes curve fitting difficult. For multimode systems, mode mixing may greatly enhance intensity of a poorly active mode. For all these reasons, it seems mandatory to take mode distortion and mode mixing into account for an accurate analysis of second-order nonlinear spectroscopic experimental data.

Controlling light absorption of graphene at critical coupling through magnetic dipole quasi-bound states in the continuum resonance

Enhancing the light-matter interaction in two-dimensional (2D) materials with high-$Q$ resonances in photonic structures has boosted the development of optical and photonic devices. Herein, we intend to build a bridge between the radiation engineering and the bound states in the continuum (BIC), and present a general method to control light absorption at critical coupling through the quasi-BIC resonance. In a single-mode two-port system composed of graphene coupled with silicon nanodisk metasurfaces, the maximum absorption of 0.5 can be achieved when the radiation rate of the magnetic dipole resonance equals to the dissipate loss rate of graphene. Furthermore, the absorption bandwidth can be adjusted more than two orders of magnitude from 0.9 nm to 94 nm by simultaneously changing the asymmetric parameter of metasurfaces, the Fermi level and the layer number of graphene. This work reveals out the essential role of BIC in radiation engineering and provides promising strategies in controlling light absorption of 2D materials for the next-generation optical and photonic devices, e.g., light emitters, detectors, modulators, and sensors.

Solving quantum trajectories for systems with linear Heisenberg-picture dynamics and Gaussian measurement noise

We study solutions to the quantum trajectory evolution of $N$-mode open quantum systems possessing a time-independent Hamiltonian, linear Heisenberg-picture dynamics, and Gaussian measurement noise. In terms of the mode annihilation and creation operators, a system will have linear Heisenberg-picture dynamics under two conditions. First, the Hamiltonian must be quadratic. Second, the Lindblad operators describing the coupling to the environment (including those corresponding to the measurement) must be linear. In cases where we can solve the $2N$-degree polynomials that arise in our calculations, we provide an analytical solution for initial states that are arbitrary (i.e. they are not required to have Gaussian Wigner functions). The solution takes the form of an evolution operator, with the measurement-result dependence captured in $2N$ stochastic integrals over these classical random signals. The solutions also allow the POVM, which generates the probabilities of obtaining measurement outcomes, to be determined. To illustrate our results, we solve some single-mode example systems, with the POVMs being of practical relevance to the inference of an initial state, via quantum state tomography. Our key tool is the representation of mixed states of quantum mechanical oscillators as state vectors rather than state matrices (albeit in a larger Hilbert space). Together with methods from Lie algebra, this allows a more straightforward manipulation of the exponential operators comprising the system evolution than is possible in the original Hilbert space.

High‐order moment multi‐sensor fusion filter design of Markov jump linear systems

To solve the problem of high-order moment Gaussian distribution (HGD) noise in state estimation, a fusion filter for Markov jump linear systems (MJLSs) with high-order moment information obtained from sensor data is designed. To obtain high-order moment information, the multi-sensor MJLS is converted to a single-mode system composed of high-order moment components by using a cumulant generating function. Next, a filter design based on Bayesian theory is established to achieve state estimation with a high-order moment information form according to the transformed single-mode deterministic system. Subsequently, a high-order moment fusion technique based on entropy theory is proposed to obtain a more accurate estimation result of the state by using the high-order moment information obtained from various sensors. Comparing the first- and second-order moment information obtained by traditional Gaussian distribution, the HGD introduces higher-order moment information and makes the fusion process more reasonable. In this way, a more precise and reasonable performance of the state estimation is achieved, depending on the sensor fusion technique. To confirm the effectiveness and advantages of the proposed method, a numerical simulation example is provided with various fusion methods. Thus, the performance of the proposed fusion filter design is verified.

Adiabaticity engineering in optical waveguides.

The fast quasi-adiabatic dynamics (FAQUAD) protocol has proven to be an effective approach to provide shortcuts to adiabatic light evolution in optical waveguides, resulting in short and robust devices. However, the FAQUAD approach of homogeneously distributing device adiabaticity only works for a single mode (polarization, wavelength, or spatial mode group) system. We propose an adiabaticity engineering approach to redistribute the adiabaticity of optical waveguides in multi-mode systems. By engineering the adiabaticity distribution using a single control parameter, we obtain shortcuts to adiabaticity in optical waveguides for multi-mode systems. The concept is applied to the design of a compact polarization-independent adiabatic 3-dB coupler on silicon.

Non-thermal effects of microwave processing on inactivation of Clostridium Sporogenes inoculated in salmon fillets

Microwave processing has been a promising technology in improving quality and ensuring microbial safety of food products, while non-thermal effects of microwave is in controversy. The objective of this study was to investigate the non-thermal effects of microwave electromagnetic (EM) fields on Clostridium Sporogenes (surrogate of Clostridium botulinum) inoculated in salmon fillets using same time-temperature profiles method. The inoculated salmon fillets were processed by a single-mode pilot microwave processing system with different radiation time (2, 3 and 4 min) and holding time (0, 2 and 4 min). Corresponding water bath treatments were designed for each microwave processing to obtain matching time-temperature profiles. Results showed that the same time-temperature profiles method was successfully achieved to evaluate the microwave non-thermal effects in salmon fillets. With equal or lower thermal lethality value, microwave processing brought significantly higher (P < 0.05) reduction values than water bath treatment. This determined the non-thermal effects of microwave EM fields. And the non-thermal effects increased with longer microwave radiation time and was intensified by higher temperature. However, the following holding section will weaken the additional inactivation efficiency of microwave non-thermal effects. Results suggested that microwave processing could provide better bacteria control with lower thermal processing level.

Multimodal Integrated Technique for Wrist Fracture Identification

Medical image processing is one of the fastest growing fields in Computer Science. It is a technique used to obtain the images of various parts of the body for clinical analysis to identify and treat diseases. Medical Imaging helps in detecting fractures, lesions present in the images like X-ray, CT-scan, and MRI. Fracture detections are difficult and sometimes may lead to the misjudgment. Existing fracture detection system is complex and accuracy of the detection is low. Hence, the proposed paper focuses on single and multi-modal system that helps radiologists in detecting the wrist fractures. The proposed system uses the multimodal system to detect the fracture in the wrist bone. It uses the combination of the Hierarchical centroid, Principal Component Analysis and Connected components analysis technique to identify the fracture in the wrist bones. This paper also elaborates on the various segmentation techniques used in the multimodal and single modal system.

Partially inscribed Bragg gratings suppressing high-order modes in high-power large-mode-area fiber oscillators

In this paper, we present the principle and design of a novel type of fiber Bragg gratings (FBGs) that are only partially inscribed into the large-mode-area fibers for high-power laser systems. The partial Bragg gratings can induce extra losses for high-order modes to suppress laser emission in direct fiber oscillators. Numerical modeling indicates these partial FBGs can very effectively limit the high-order LP11 mode from lasing and maintain the fundamental LP01 mode operation under up to 5 kW pump power, even for fibers of extremely large mode areas with core diameters up to 50 μm. Therefore, such partial FBGs can be excellent modal quality control components for single-mode high-power laser systems constructed with fibers of very large mode areas.

Measuring nonclassicality of single-mode systems

Nonclassicality of a single-mode state can be quantified by the entanglement (potential) the state creates at the output of a beam splitter. Thus, beam splitter transformation can be utilized for obtaining single-mode nonclassicality conditions (quantifications) from two-mode entanglement criteria (measures). Here, (i) we employ this relation to quantify the single-mode nonclassicality (SMNc) of a nonlinear crystal field generating second harmonic signals. (ii) We also manage to witness the SMNc of superradiant emission, a non-Gaussian state, in a Dicke phase transition. Entanglement potential, at the beam splitter output, is obtained in terms of measurable single-mode quantities. Thus, presence of a beam splitter in an experiment is not necessary. Employing the beam splitter method, one can also utilize hybrid entanglement criteria as SMNc conditions working well in different classes of single-mode states. (iii) We also work on essentials of the entanglement-SMNc relation: one obtains the generalized squeezing condition ⟨â†â⟩ < |⟨â2⟩| as the SMNc condition when an optimized form of Duan–Giedke–Cirac–Zoller criterion [PRL 84, 2722] is used at the output of the beam splitter.

Sinterability of Silicon Carbide and Boron Carbide under Single-Mode Microwave Fields

The feasibility of processing silicon carbide (SiC) and boron carbide (B4C) using a 2.45 GHz single-mode microwave system has been investigated. In order to determine the appropriate sintering conditions, samples were processed under various electric/magnetic (E/H) field ratios. Proportional 50% E/H-field ratios and 100% H-field conditions resulted in higher sample temperatures up to 1500 °C under equivalent microwave power. Sinterability was improved by adding B4C and carbon to SiC, but limited to a thin outer layer of the pellet. While partial densification was observed under all conditions, isolated regions of full densification in microwave-processed B4C samples were observed under 100% H-field mode. Microstructural analysis of microwave-processed SiC with and without additives indicated non-uniform sintering, while B4C showed evidence of relatively homogeneous microstructures.