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The Rotary-Motion Extended Array Synthesis spacecraft is a dual-spin spacecraft with long tethers held in tension by the spin. This paper derives the free-space (not considering orbital effects) dy...

In this study, an equivalent multi-body dynamics model of a rotary compressor for a household air-conditioner is established to predict its vibration responses when eccentric masses on the cranksha...

Cold plasma is a novel nonthermal technology that has been used for preserving and maintaining the quality of food materials. Researchers developed numerous cold plasma equipment to study the effect of plasma on food materials; however, the degree of processing such as flow of plasma species from the source of plasma to the food material and their interaction/diffusion into the food, differs with respect to the equipment. The computational study can simulate the flow dynamics of plasma which in turn can improve the efficiency of processing and design aspects. Computational fluid dynamics (CFD) is the most reliable, cost-effective, and robust numerical tool used for simulating various high-end food processing technologies. In cold plasma processing, computational study aids in revealing the distribution of reactive species and their flow dynamics on the target surface. As CFD studies on plasma interaction with food materials are not available, this review is focused on covering the basics of using CFD in cold plasma simulation. It also explores the significant use of CFD in cold plasma simulation in various sectors along with its possible and futuristic applications in food processing.

The effect of the optical feedback on the polarization flipping point and hysteresis loop was studied. The polarization flipping occurred at all angles between the polarizer axis and the laser polarization. The polarization flipping point changed by an optical feedback occurred at angles from 0° to 90°. Ability of choosing or controlling the laser polarization was determined by changing the direction of vertical and horizontal polarization by polarizer rotation in the external cavity from 0° to 90°.

BACKGROUND Visualization of aortic valve dynamics is important in diagnosing valvular diseases but is challenging to perform with magnetic resonance imaging (MRI) due to the limited temporal resolution. PURPOSE To develop an MRI technique with sub-millisecond temporal resolution and demonstrate its application in visualizing rapid aortic valve opening and closing in human subjects in comparison with echocardiography and conventional MRI techniques. STUDY TYPE Prospective. POPULATION Twelve healthy subjects. FIELD STRENGTH/SEQUENCE 3 T; gradient-echo-train-based sub-millisecond periodic event encoded imaging (get-SPEEDI) and balanced steady-state free precession (bSSFP). ASSESSMENT Images were acquired using get-SPEEDI with a temporal resolution of 0.6 msec. get-SPEEDI was triggered by an electrocardiogram so that each echo in the gradient echo train corresponded to an image at a specific time point, providing a time-resolved characterization of aortic valve dynamics. For comparison, bSSFP was also employed with 12 msec and 24 msec temporal resolutions, respectively. The durations of the aortic valve rapid opening (Tro ), rapid closing (Trc ), and the maximal aortic valve area (AVA) normalized to height were measured with all three temporal resolutions. M-mode echocardiograms with a temporal resolution of 0.8 msec were obtained for further comparison. STATISTICAL TEST Parameters were compared between the three sequences, together with the echocardiography results, with a Mann-Whitney U test. RESULTS Significantly shorter Tro (mean ± SD: 27.5 ± 6.7 msec) and Trc (43.8 ± 11.6 msec) and larger maximal AVA/height (2.01 ± 0.29 cm2 /m) were measured with get-SPEEDI compared to either bSSFP sequence (Tro of 56.3 ± 18.8 and 63.8 ± 20.2 msec; Trc of 68.2 ± 16.6 and 72.8 ± 18.2 msec; maximal AVA/height of 1.63 ± 0.28 and 1.65 ± 0.32 cm2 /m for 12 msec and 24 msec temporal resolutions, respectively, P

This paper deals with the attitude motion of LEO satellites with deployable side panels designed for passive aerodynamic stabilization in a rarefied atmosphere. The influence of the aerodynamic and gravitational torques on the planar attitude motion near the unstable and stable equilibrium positions is studied. The presence of the unstable equilibrium position and small perturbations such as the oscillations of the flexible panels is the cause of chaos. A critical altitude is found above which the chaos is possible. The equations of planar attitude motion of the satellite with deployed flexible panels are obtained. The chaotic behavior of the system is demonstrated through numerical simulations of the attitude motion of a 3U CubeSat. The results of this paper can be used to analyze the applicability of passive aerodynamic stabilization for LEO satellites.

An efficient comprehensive vibration analysis method for a helicopter rotor–fuselage coupling system is presented. This loose computational fluid dynamics (CFD)/computational structural dynamics (CSD) coupling approach with a free wake–panel coupled model is used for system vibration response analysis. The CSD model of the helicopter consists of a fuselage model using a refined three dimensional (3 D) finite element model (FEM) and a rotor model consisting of nonlinear moderate deflection beam elements with 15 degrees of freedom. The unsteady Euler CFD solver is used for the flow field analysis of the entire vehicle. The induced inflow of the quasi-steady aerodynamic force is calculated with the free wake–panel coupled model, which is used to simulate rotor–fuselage aerodynamic interference. Using a full-scale helicopter as an example, the vibration responses of the typical fuselage position in hovering and level flights are analysed. When compared with the literature results and flight test data, the predictions of the proposed method are closer to the test data than those of the traditional method in hovering and low forward ratio flights, and the difference between the two methods is minimal in high forward ratio flight.

This paper investigates the dynamics of an orbital siphon anchored to a rotating ellipsoidal asteroid. The siphon is a chain of tether-connected payload masses arranged vertically from the asteroid surface, envisaged for propellantless delivery of payloads (e.g., mined material) from the asteroid surface to a collecting spacecraft. If the structure is long enough, the centrifugal-induced force can overcome the gravitational force on the payloads, eventually allowing resource payloads to escape. By connecting new payloads at the bottom of this chain while removing upper payloads a net orbital siphon effect is established, which provides a net continuous flow of resources from the asteroid surface to a collecting spacecraft, attached at the top of the siphon. The dynamics of the siphon is investigated in detail by varying a set of relevant parameters, in particular, chain length, anchor location and asteroid shape. It is shown that the system exhibits oscillatory behaviour in the equatorial plane, with decreasing oscillation amplitude over time and that the longest equatorial end is the best anchor location to guarantee proper siphon operation while minimizing the chain length. Eventually, a method is proposed to exploit the equatorial Coriolis-induced oscillations of the siphon to transfer payload masses from the collecting spacecraft to the stable equilibrium points associated with the effective potential of the ellipsoidal asteroid, where a catcher would collect the material.

Dynamical systems with position varying mass are archetypal examples of classical mechanical systems with rocket engine being a typical realistic model. In the present study, we extend the classical Newtonian mechanics by replacing the kinetic energy by a nonlocal-in-time kinetic energy and the standard velocity by a fractional velocity. These replacements lead to an extension of Newton’s second law of motion which has interesting implications in incompressible fluid dynamics. As an application, we discuss the rotating fluid problem subject to a position varying fluid mass which occurs in rocket dynamics. Several features were observed, mainly the transition from order to disorder in rotating fluids in rockets.

The attitude dynamics of a nanosatellite (NS) with one movable unit changing its angular position relative to a main body of the nanosatellite is considered. This relative movability of the unit can be implemented with the help of flexible rods of variable length connecting the unit with the main body. Change of the relative position of the movable unit shifts the center of mass of the entire mechanical system. The NS has a single jet engine rigidly mounted into the NS main body. The shift of the mass center creates an arm of the jet-engine thrust and a corresponding control torque. Schemes to control the attitude dynamics of the satellite using the movability of its unit are developed, using both the torque from the engine and inertia change.

Quantum dot (QD) is slated to play a significant role in quantum technologies through its usage as a single-photon source. It also has promising applications as efficient light emitters through str...

With large eddy simulations (LES) and/or cloud-resolving models (CRMs), it is now possible to simultaneously simulate shallow and deep convection. However, using traditional methods, the computational expense is typically very large, due to the small grid spacings needed to resolve shallow clouds. Here, the main purpose is to present a method that is computationally less expensive by a factor of roughly 10 to 50. Unlike traditional grid stretching of only the vertical z grid spacing, the present method involves expansion of the grid spacing in all coordinate directions (x,y,z) and time t. A ˝ne grid spacing of O(10)-O(100) m can be used near the surface to resolve boundary layer turbulence, and the grid spacing expands to be O(1000) m at higher altitudes, which reduces computational cost while still resolving deep convection. Example simulations are conducted with a simpli˝ed LES/CRM in 2D to verify the theoretical cost savings.

We consider optical pulse propagation in cubic-quintic nonlinear media and analyze the dynamics of pulse compression within the framework of variational approach. Based on a potential model we find...

Dynamics evaluation is one of the core research contents of robotics, especially for the parallel manipulators, which are usually working with high acceleration. The general dynamics evaluation methods mainly deal with the acceleration of end-effector and magnitude of driving force based on the general inertia/mass matrix, and ignore the gravity. However, with the change of the placement mode of a parallel manipulator, the gravity would have a great effect on the dynamics of a heavy parallel manipulator. On the other hand, there still some other properties should be evaluated, such as the acceleration sensitivity of each driving shaft caused by gravity, the driving force uniformity when driving force achieves its maximum value. For these reasons, this paper investigates a dynamics evaluation method considering gravity and driving force uniformity. First, the limitations of general evaluation methods are described; next, the proposed dynamics evaluation method is given, including acceleration sensitivity analysis and the driving force uniformity; finally, by taking a typical horizontal parallel tool head as an example of study, a complete dynamics evaluation work is performed by using the proposed method.

A general methodology for the dynamics of spacecraft with rigid–liquid–flexible body coupling is established by using Kane’s equations, whereby the combined sloshing in multiple tanks and the dynam...

We investigate the transport of excitons and trions in monolayer semiconductor WS$_2$ subjected to controlled non-uniform mechanical strain. We actively control and tune the strain profiles with an AFM-based setup in which the monolayer is indented by an AFM tip. Optical spectroscopy is used to reveal the dynamics of the excited carriers. The non-uniform strain configuration locally changes the valence and conduction bands of WS$_2$, giving rise to effective forces attracting excitons and trions towards the point of maximum strain underneath the AFM tip. We observe large changes in the photoluminescence spectra of WS$_2$ under strain, which we interpret using a drift-diffusion model. We show that the transport of neutral excitons, a process that was previously thought to be efficient in non-uniformly strained 2D semiconductors and termed as "funneling", is negligible at room temperature in contrast to previous observations. Conversely, we discover that redistribution of free carriers under non-uniform strain profiles leads to highly efficient conversion of excitons to trions. Conversion efficiency reaches $\simeq 100\%$ even without electrical gating. Our results explain inconsistencies in previous experiments and pave the way towards new types of optoelectronic devices., 6 pages, 4 figures

Nonlinear dynamic modeling methods for a flower-like clustered deployable space telescope (DST) with laminated composite material experiencing large deployment and attitude adjustment motions is pr...

This article deals with the finite element (FE) modeling and dynamics analysis of bidirectional functionally graded (2D-FG) rotating shaft system considering temperature-independent (TID) and tempe...

We propose and demonstrate a two-dimensional 4-bit fully optical nonvolatile memory using Ge2Sb2Te5 (GST) phase change materials, with encoding via a 1550 nm laser. Using the telecom-band laser, we...

Investigations on solitons have been carried out for decades in various areas of physics, such as nonlinear photonics, magnetic matter and superconductors. However, producing multidimensional solitary states and manipulation of their motion are still big challenges. In this work, we describe the formation of dynamic multidimensional solitons in a nematic and a cholesteric liquid crystal (LC). These solitons are self-confined director perturbations that propagate rapidly through the LC bulk and preserve their identities after collisions. We tune the velocity of the solitons by electric fields and control their trajectories through alignment layers. We find that the chirality of the cholesteric LC endows the solitons a wave-particle duality, and leads to a variety of fascinating interactions between solitons which cannot be observed in the achiral nematic LC. Furthermore, we also show that these solitons can be used as vehicles for 2D delivery of micro-cargos. Generating and manipulating solitons in more than one dimension is a major challenge in nonlinear matter physics. This paper reports an experimental investigation of the structure, generation, dynamic behaviour, and manipulation of multidimensional solitons in cholesteric liquid crystals

Tensegrity structures have unique features such as low mass to payload ratio, strength, and robustness. Therefore, they present great potential in robotics, aerospace, and civil engineering. The dynamics of tensegrity robots is highly nonlinear and constrained. As a result, their modeling, simulation, state estimation, and control are non-trivial. Strings in tensegrity structures are usually modeled as linear springs. Utilization of nonlinear elastic/damping elements in tensegrities would further enrich their dynamics and endow them with additional properties, such as multiple equilibrium configurations. In this paper, our preliminary work on the dynamics of actuated tensegrities with strings containing nonlinear elastic and/or damping elements is presented. At first, the formulation of tensegrity dynamics with general nonlinear elastic/damping elements is explored. Later dynamics of tensegrities with negative stiffness honeycombs incorporated into strings are considered. Simulations are performed on three tensegrity systems: two-bar, three-bar, and six-bar structures. Results demonstrate that negative stiffness honeycombs result in nonlinear steady-state response to constant external force, reduced force magnitudes in strings and bars, and increased range of motion.

A mathematical model for synchronization of two single-mode semiconductor lasers is built within the framework of the rate equations approximation. The model has the form of a system of nonlinear ordinary differential equations for electron concentrations and photon densities in both lasers. The lasers are coupled in such a way that the cavity losses of each device are proportional to the light intensity emitted by the other. Besides, the equations take into account the nonlinear (quadratic) losses. The system is analyzed by the methods of bifurcation theory and multiple scale techniques. It is shown that the model exhibits different behavior at strong and weak coupling between the lasers. At strong coupling, there is no oscillation in the system, though the phenomena of bistability and hysteresis are possible. At weak coupling, a stable limit cycle and spiky relaxation oscillations may emerge. It is found that synchronous oscillations of the photon density in lasers occur in antiphase. The proposed synchronization scheme could be useful in obtaining long-period pulsations.

In this paper, numerical investigation is carried out on two-dimensional Ahmed body model using Computational Fluid Dynamics in ANSYS Fluent 19.1. The 2-D model is designed in Catia v5 for 25°, 35° and 45° slant angles. The turbulent model used to analyze the flow dynamics is Realizable k-ε model. The drag coefficient variation with respect to slant angle is computed. The skin friction coefficient, wall shear stress and frictional velocity are also calculated.

A family of configuration spaces in the description of the internal dynamics of a rigid molecule has been considered. It has been shown that the requirement of the physical correctness of the description leads to serious restrictions for such spaces. In particular, only spaces satisfying the Eckart condition are allowed for a nonlinear rigid molecule.

The problem of modeling the attitude-control modes of small spacecraft with the use of electromagnetic systems, interacting with the Earths magnetic field is considered. A small spacecraft angular motion mathematical model is developed. A control law for magnetic attitude control system of small spacecraft is formulated. Results of satellite with magnetic attitude control system movement numerical modelling are presented.

The problem of modeling the attitude control modes of small spacecraft using electromagnetic systems interacting with the Earth’s magnetic field is considered. A mathematical model for the angular motion dynamics of small spacecraft has been developed. The control law for linear magnetic attitude control systems of small spacecraft is formulated. The results of our numerical modeling of the motion of a satellite with a magnetic attitude control system are presented.

The Hamiltonian for a system of two two-level atoms separately located in two cavities coupled through the overlap of the evanescent cavity fields in presence of an external classical fields is introduced. It is simplified by using unitary canonical transformations for both the atomic and photonic modes. The atomic population inversion and the degree of entanglement are considered. Different interactions are addressed within a temporal evolution of the system in correspondence with three dispersive regimes limits. Analytical expressions of the coefficients of the time dependent wavefunctions of the different Hamiltonians are derived. The influences of the photon hopping strength, detuning and the couplings of the external classical fields on the behavior of the atomic population inversion and the atomic entropies and degree of entanglement are investigated. The interrelation between the 1st-atom entanglement and the atomic population inversion is noted. General conclusions reached are illustrated through numerical results.

BackgroundResting state beta band (13 – 30 Hz) oscillations represent pathological neural activity in Parkinson’s disease (PD). It is unknown how the peak frequency or dynamics of beta oscillations may change among fine, limb and axial movements and different disease phenotypes. This will be critical for the development of personalized closed loop deep brain stimulation (DBS) algorithms during different activity states.MethodsSubthalamic (STN) local field potentials (LFPs) were recorded from a sensing neurostimulator (Activa® PC+S, Medtronic PLC.,) in fourteen PD participants (six tremor-dominant, 8 akinetic-rigid) off medication/off STN DBS during thirty seconds of repetitive alternating finger tapping, wrist-flexion extension, stepping in place, and free walking. Beta power peaks and beta burst dynamics were identified by custom algorithms and were compared among movement tasks and between tremor-dominant and akinetic-rigid groups.ResultsBeta power peaks were evident during fine, limb, and axial movements in 98% of movement trials; the peak frequencies were similar during each type of movement. Burst power and duration were significantly larger in the high beta band, but not in the low beta band, in the akinetic-rigid group compared to the tremor-dominant group.ConclusionsThe conservation of beta peak frequency during different activity states supports the feasibility of patient-specific closed loop DBS algorithms driven by the dynamics of the same beta band during different activities. Akinetic-rigid participants had greater power and longer burst durations in the high beta band than tremor-dominant participants during movement, which may relate to the difference in underlying pathophysiology between phenotypes.

The snap of a finger has been used as a form of communication and music for millennia across human cultures. However, a systematic analysis of the dynamics of this rapid motion has not yet been performed. Using high-speed imaging and force sensors, we analyse the dynamics of the finger snap. We discover that the finger snap achieves peak angular accelerations of 1.6 × 10 6 ° s −2 in 7 ms, making it one of the fastest recorded angular accelerations the human body produces (exceeding professional baseball pitches). Our analysis reveals the central role of skin friction in mediating the snap dynamics by acting as a latch to control the resulting high velocities and accelerations. We evaluate the role of this frictional latch experimentally, by covering the thumb and middle finger with different materials to produce different friction coefficients and varying compressibility. In doing so, we reveal that the compressible, frictional latch of the finger pads likely operates in a regime optimally tuned for both friction and compression. We also develop a soft, compressible friction-based latch-mediated spring actuated model to further elucidate the key role of friction and how it interacts with a compressible latch. Our mathematical model reveals that friction plays a dual role in the finger snap, both aiding in force loading and energy storage while hindering energy release. Our work reveals how friction between surfaces can be harnessed as a tunable latch system and provides design insight towards the frictional complexity in many robotic and ultra-fast energy-release structures.

Psychophysics has long focused on measuring the stimulus intensity that reaches the threshold for conscious report. However, variability in the neural activity evoked by the stimulus results in variable perceptual sensitivity for the same level of stimulus intensity. These variable fluctuations in neural activity have therefore been regarded as a source of noise, impairing the threshold for conscious perception estimated from signal detection theory. Recently we have found that variable fluctuations in cortical responses are due, in part, to the state of traveling waves of spontaneous cortical activity (Davis et al., Nature, 2020). These waves modulate stimulus-evoked spiking activity and perceptual sensitivity in marmosets trained to detect faint visual targets. Thus, in contrast to the traditional view of fluctuations as harmful noise, traveling waves improve perceptual thresholds. To gain insight into the mechanisms underlying traveling waves, we study a large-scale spiking network model with conductance-based synapses, biologically realistic topographic connectivity, and action potential propagation speeds consistent with those observed in unmyelinated horizontal fibers. We found that these properties were sufficient to generate spontaneous waves across the entire range of network parameters that produced asynchronous-irregular spiking dynamics (Brunel, J Comput Neurosci, 2000; Renart et al., Science, 2010). Further, we found that neuronal participation in these waves was sparse, enabling traveling waves to coexist with asynchronous-irregular spiking activity without necessarily inducing correlations, which have been found to impair perception (Nandy et al., eLife, 2019). This sparse-wave network regime remained sensitive to feed-forward input and modulated the strength of stimulus-evoked responses as observed in the cortex. This was in contrast to networks that produced dense spiking waves, which drove strong correlations and rendered the network insensitive to feed-forward input. Traveling waves appear to be an intrinsic feature of cortical dynamics, and they therefore likely impact the moment-to-moment processing of information throughout the brain.

Understanding and optimising the mechanisms of generation and extraction of hot carriers in plasmonic heterostructures is important for applications in new types of photodetectors, photochemistry and photocatalysis, as well as nonlinear optics. Here, we show using transient dynamic measurements that the relaxation of the excited hot-carriers in Au/Pt hetero-nanostructures is accelerated through the transfer pathway from Au, where they are generated, to Pt nanoparticles, which act as a hot-electron sink. The influence of the environment on the dynamics was also demonstrated. The time-resolved photoluminescence measurements confirm the modified hot-electron dynamics, revealing quenching of the photoluminescence signal from Au nanoparticles in the presence of Pt and an increased photoluminescence lifetime. These observations are signatures of the improved extraction efficiency of hot-carriers by the Au/Pt heterostructures. The results give insight into the time-dependent behaviour of excited compound nanoscale systems and provide a way of controlling the relaxation mechanisms involved, with important consequences for engineering nonlinear optical response and hot-carrier-assisted photochemistry.

Spacecraft attitude describes the rotational motion of a spacecraft around its center of mass, often by the orientation or direction of its fixed body frame with respect to a reference frame.

Deep learning (DL) is applied to simulate non-adiabatic molecular dynamics of phenanthrene, using the time-dependent density functional based tight binding (TD-DFTB) approach for excited states combined with mixed quantum–classical propagation. Reference calculations rely on Tully’s fewest-switches surface hopping (FSSH) algorithm coupled to TD-DFTB, which provides electronic relaxation dynamics in fair agreement with various available experimental results. Aiming at describing the coupled electron-nuclei dynamics in large molecular systems, we then examine the combination of DL for excited-state potential energy surfaces (PESs) with a simplified trajectory surface hopping propagation based on the Belyaev–Lebedev (BL) scheme. We start to assess the accuracy of the TD-DFTB approach upon comparison of the optical spectrum with experimental and higher-level theoretical results. Using the recently developed SchNetPack (Schütt et al 2019 J. Chem. Theory Comput. 15 448–55) for DL applications, we train several models and evaluate their performance in predicting excited-state energies and forces. Then, the main focus is given to the analysis of the electronic population of low-lying excited states computed with the aforementioned methods. We determine the relaxation timescales and compare them with experimental data. Our results show that DL demonstrates its ability to describe the excited-state PESs. When coupled to the simplified BL scheme considered in this study, it provides reliable description of the electronic relaxation in phenanthrene as compared with either the experimental data or the higher-level FSSH/TD-DFTB theoretical results. Furthermore, the DL performance allows high-throughput analysis at a negligible cost.

We experimentally investigate the complex dynamics of a multi-mode quantum-dot semiconductor laser with time-delayed optical feedback. We examine a two-dimensional bifurcation diagram of the quantum-dot laser as a comprehensive dynamical map by changing the injection current and feedback strength. We found that the bifurcation diagram contains two different parameter regions of low-frequency fluctuations. The power-dropout dynamics of the low-frequency fluctuations are observed in the sub-GHz region, which is considerably faster than the conventional low-frequency fluctuations in the MHz region. Comparing the dynamics of quantum-dot laser with those of single- and multi-mode quantum-well semiconductor lasers reveals that the fast low-frequency fluctuation dynamics are unique characteristics of quantum-dot lasers with time-delayed optical feedback.

High speed volumetric optical microscopy is an important tool for observing rapid processes in living cells or for real-time tracking of sub-cellular components. However, the 3D imaging capability often comes at the price of a high technical complexity of the imaging system and/or the requirement of demanding image analysis. Here, we propose a combination of conventional phase-contrast imaging with a customized multi-plane beam-splitter for enabling simultaneous acquisition of images in eight different focal planes. Our method is technically straightforward and does not require complex post-processing image analysis. We apply our multi-plane phase-contrast microscope to the real-time observation of the fast motion of reactivated Chlamydomonas axonemes with sub-µm spatial and 4 ms temporal resolution. Our system allows us to observe not only bending but also the three-dimensional torsional dynamics of these micro-swimmers.

We report an Aubrey-Andre-Harper (AAH) model based quasi-periodic lossless evanescently coupled waveguide lattice to study the unconventional physics of light localization. We find an exclusively new way to establish localization phase transition in a 1D-AAH lattice by observing the slope variation of the band and accordingly study the modal characteristics to reveal the fact that a higher value of quasi-periodic modulation strength is imperative for observing a signature of fully localized light states having higher eigenenergy. This analytical concept has numerically been implemented in the proposed quasi-periodic lattice to achieve light localization, where we have shown that the supported states not only depend on localization phase transition parameter, but also on the specific location of excitation which is due to quasi-periodic nature of lattice. Furthermore, we have investigated a unique effect of the presence of disorder on light localization phenomenon, where it has been reported that the presence of off-diagonal disorder, which is otherwise detrimental, favours light localization in the proposed structure due to its quasi-periodic nature. The findings indeed have the potential to open up a fertile platform to manipulate light in passive photonic devices.