Realization of Polymeric Electro-Optic Modulators with Less Than One Volt Drive Voltage Requirement

1999 ◽  
Vol 598 ◽  
Author(s):  
Cheng Zhang ◽  
Michael Lee ◽  
Adam Winklemann ◽  
Heidi Northcroft ◽  
Christopher Lindsey ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Field Strength ◽  
Electrostatic Interactions ◽  
Theoretical Calculations ◽  
Polymer Materials ◽  
Poling Field ◽  
New Paradigm ◽  
Electro Optic ◽  
Synthetic Approaches ◽  
Theoretical Results

ABSTRACTThe roles played by spatially anisotropic intermolecular electrostatic interactions, chromophore shape, host dielectric constant, and poling field strength in defining maximum achievable electro-optic activity for electrically poled chromophore/polymer materials are investigated by equilibrium and Monte-Carlo quantum statistical mechanical calculations. Even simple Hamiltonians reproduce critical qualitative features such as the existence of a maximum in plots of electro-optic activity versus chromophore number density in a polymer matrix. Comparison of theoretical results for various methods provides a useful check on the validity of approximations employed with individual methods. The most significant conclusion to derive from a comparison of experimental and theoretical results is the dependence of maximum achievable electro-optic activity upon chromophore shape. Theoretical calculations suggest a new paradigm for the design of optimum electro-optic chromophores; realization of the desired shapes may be facilitated by dendritic synthetic approaches. In the presence of intermolecular electrostatic interactions, the dependence of electro-optic activity upon material dielectric permittivity and electric poling field strength is more complex than in the absence of such interactions. Of particularly, interest are conditions that lead to second order phase transitions to lattices containing centrically (antiferroelectricallly) ordered chromophore domains. Such phase transitions can lead to further complications in the attempted preparation of device quality materials but can be effectively avoided by utilization of theoretically derived phase diagrams.

MANUFACTURE INVESTIGATION OF CARTRIDGE WITH BOTTOM-MOST PART FLANGE BY DIRECT EXTRUSION WITH COUNTERPUNCH. REPORT 18. EXPERIMENTAL CHECK OF THEORETICAL RESULTS FOR DIFFERENT HOLLOW RADIUSES AND BOTTOM-MOST PART THICKNESSES

2020 ◽  
Vol 0 (9) ◽  
pp. 16-23
Author(s):  
A. L. Vorontsov ◽  
◽  
I. A. Nikiforov ◽  
Keyword(s):  
Strain Hardening ◽  
Theoretical Calculations ◽  
High Accuracy ◽  
Geometric Parameters ◽  
Strength Characteristics ◽  
Experimental Check ◽  
Hardening Material ◽  
Direct Extrusion ◽  
Theoretical Results

The results of an experimental check of the obtained theoretical formulae allowing us to determine the most important parameters of extrusion cartridges with a counterpunch for different hollow radiuses and bottom-most part thicknesses are presented. Characteristics of used tools, geometric parameters of extrusion experiments, strength characteristics of deformed materials and lubricants are described in detail. Both strain-hardening material and strain-unhardening material were studied. Methodology of the theoretical calculations is demonstrated in detail. High accuracy of the obtained design formulae was confirmed.

scholarly journals Figures of merit for stellarators near the magnetic axis

2021 ◽  
Vol 87 (1) ◽  
Author(s):  
Matt Landreman
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Axis ◽  
Configuration Design ◽  
New Paradigm ◽  
First Order ◽  
Figures Of Merit ◽  
Minor Radius ◽  
Error Field ◽  
Quantities Of Interest

A new paradigm for rapid stellarator configuration design has been recently demonstrated, in which the shapes of quasisymmetric or omnigenous flux surfaces are computed directly using an expansion in small distance from the magnetic axis. To further develop this approach, here we derive several other quantities of interest that can be rapidly computed from this near-axis expansion. First, the $\boldsymbol {\nabla }\boldsymbol {B}$ and $\boldsymbol {\nabla }\boldsymbol {\nabla }\boldsymbol {B}$ tensors are computed, which can be used for direct derivative-based optimization of electromagnetic coil shapes to achieve the desired magnetic configuration. Moreover, if the norm of these tensors is large compared with the field strength for a given magnetic field, the field must have a short length scale, suggesting it may be hard to produce with coils that are suitably far away. Second, we evaluate the minor radius at which the flux surface shapes would become singular, providing a lower bound on the achievable aspect ratio. This bound is also shown to be related to an equilibrium beta limit. Finally, for configurations that are constructed to achieve a desired magnetic field strength to first order in the expansion, we compute the error field that arises due to second-order terms.

scholarly journals Private and rateless adaptive coded matrix-vector multiplication

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Rawad Bitar ◽  
Yuxuan Xing ◽  
Yasaman Keshtkarjahromi ◽  
Venkat Dasari ◽  
Salim El Rouayheb ◽  
...  
Keyword(s):  
Computing Methods ◽  
Erasure Codes ◽  
Time Varying ◽  
New Paradigm ◽  
Matrix Vector Multiplication ◽  
Processing Data ◽  
Computationally Intensive ◽  
Matrix Vector ◽  
Monitoring Devices ◽  
Theoretical Results

AbstractEdge computing is emerging as a new paradigm to allow processing data near the edge of the network, where the data is typically generated and collected. This enables critical computations at the edge in applications such as Internet of Things (IoT), in which an increasing number of devices (sensors, cameras, health monitoring devices, etc.) collect data that needs to be processed through computationally intensive algorithms with stringent reliability, security and latency constraints. Our key tool is the theory of coded computation, which advocates mixing data in computationally intensive tasks by employing erasure codes and offloading these tasks to other devices for computation. Coded computation is recently gaining interest, thanks to its higher reliability, smaller delay, and lower communication costs. In this paper, we develop a private and rateless adaptive coded computation (PRAC) algorithm for distributed matrix-vector multiplication by taking into account (1) the privacy requirements of IoT applications and devices, and (2) the heterogeneous and time-varying resources of edge devices. We show that PRAC outperforms known secure coded computing methods when resources are heterogeneous. We provide theoretical guarantees on the performance of PRAC and its comparison to baselines. Moreover, we confirm our theoretical results through simulations and implementations on Android-based smartphones.

scholarly journals Nonreciprocal charge transport up to room temperature in bulk Rashba semiconductor α-GeTe

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yan Li ◽  
Yang Li ◽  
Peng Li ◽  
Bin Fang ◽  
Xu Yang ◽  
...  
Keyword(s):  
Charge Transport ◽  
Room Temperature ◽  
Theoretical Calculations ◽  
Ferromagnetic Layer ◽  
Spin Splitting ◽  
New Paradigm ◽  
Rashba Spin ◽  
Rashba Spin Splitting ◽  
Fundamental Insight ◽  
Insight Into

AbstractNonmagnetic Rashba systems with broken inversion symmetry are expected to exhibit nonreciprocal charge transport, a new paradigm of unidirectional magnetoresistance in the absence of ferromagnetic layer. So far, most work on nonreciprocal transport has been solely limited to cryogenic temperatures, which is a major obstacle for exploiting the room-temperature two-terminal devices based on such a nonreciprocal response. Here, we report a nonreciprocal charge transport behavior up to room temperature in semiconductor α-GeTe with coexisting the surface and bulk Rashba states. The combination of the band structure measurements and theoretical calculations strongly suggest that the nonreciprocal response is ascribed to the giant bulk Rashba spin splitting rather than the surface Rashba states. Remarkably, we find that the magnitude of the nonreciprocal response shows an unexpected non-monotonical dependence on temperature. The extended theoretical model based on the second-order spin–orbit coupled magnetotransport enables us to establish the correlation between the nonlinear magnetoresistance and the spin textures in the Rashba system. Our findings offer significant fundamental insight into the physics underlying the nonreciprocity and may pave a route for future rectification devices.

scholarly journals IV. On the dynamical theory of incompressible viscous fluids and the determination of the criterion

1895 ◽  
Vol 186 ◽  
pp. 123-164 ◽  
Keyword(s):  
Singular Solution ◽  
Physical State ◽  
Theoretical Calculations ◽  
Equations Of Motion ◽  
Dynamical Theory ◽  
Viscous Fluids ◽  
Linear Functions ◽  
Incompressible Viscous Fluids ◽  
Theoretical Results

1. The equations of motion of viscous fluid (obtained by grafting on certain terms to the abstract equations of the Eulerian form so as to adapt these equations to the case of fluids subject to stresses depending in some hypothetical manner on the rates of distortion, which equations Navier seems to have first introduced in 1822, and which were much studied by Cauchy and Poisson) were finally shown by St. Venant and Sir Gabriel Stokes, in 1845, to involve no other assumption than that the stresses, other than that of pressure uniform in all directions, are linear functions of the rates of distortion, with a co-efficient depending on the physical state of the fluid. By obtaining a singular solution of these equations as applied to the case of pendulums in steady periodic motion, Sir G. Stokes was able to compare the theoretical results with the numerous experiments that had been recorded, with the result that the theoretical calculations agreed so closely with the experimental determinations as seemingly to prove the truth of the assumption involved. This was also the result of comparing the flow of water through uniform tubes with the flow calculated from a singular solution of the equations so long as the tubes were small and the velocities slow. On the other hand, these results, both theoretical and practical, were directly at variance with common experience as to the resistance encountered by larger bodies moving with higher velocities through water, or by water moving with greater velocities through larger tubes. This discrepancy Sir G. Stokes considered as probably resulting from eddies which rendered the actual motion other than that to which the singular solution referred and not as disproving the assumption.

Electro-optic polymer materials and devices: fundamental limits

1993 ◽  
Author(s):  
Richard S. Lytel ◽  
George F. Lipscomb ◽  
Anthony J. Ticknor
Keyword(s):  
Polymer Materials ◽  
Fundamental Limits ◽  
Electro Optic

Macroscopic Order and Electro-Optic Response of Dipolar Chromophore-Polymer Materials

ChemPhysChem ◽  
2004 ◽  
Vol 5 (12) ◽  
pp. 1821-1830 ◽  
Author(s):  
Yuriy V. Pereverzev ◽  
Oleg V. Prezhdo ◽  
Larry R. Dalton
Keyword(s):  
Polymer Materials ◽  
Electro Optic

Rational Design of Organic Electro-Optic Materials

2001 ◽  
Vol 708 ◽  
Author(s):  
Alex Jen ◽  
Robert Neilsen ◽  
Bruce Robinson ◽  
William H. Steier ◽  
Larry Dalton
Keyword(s):  
Wavelength Division Multiplexing ◽  
Material Properties ◽  
Electrostatic Interactions ◽  
Rational Design ◽  
Elevated Temperatures ◽  
Optical Loss ◽  
Quality Factors ◽  
Electro Optic ◽  
Lattice Hardening

ABSTRACTA number of material properties must be optimized before organic electro-optic materials can be used for practical device applications. These include electro-optic activity, optical transparency, and stability including both thermal and photochemical stability. Exploiting an improved understanding of the structure/function relationships, we have recently prepared materials exhibiting electro-optic coefficients of greater than 50 pm/V and optical loss values of less than 0.7 dB/cm at the telecommunication wavelengths of 1.3 and 1.55 microns. When oxygen is excluded to a reasonable extent, long-term photostability to optical power levels of 20 mW has been observed. Photostability is further improved by addition of scavengers and by lattice hardening. Long-term (greater than 1000 hours) thermal stability of poling-induced electro-optic activity is also observed at elevated temperatures (greater than 80°C) when appropriate lattice hardening is used. The successful improvement of organic electro-optic materials rests upon (1) attention to the design of chromophore structure including design to inhibit unwanted intermolecular electrostatic interactions and to improve chromophore instability and (2) attention to processing conditions including those involved in spin casting, electric field poling, and lattice hardening. A particularly attractive new direction has been the exploitation of dendrimer structures and particularly of multi-chromophore containing dendrimer structures. This approach has permitted the simultaneous improvement of all material properties. Development of new materials has facilitated the fabrication of a number of prototype devices and most recently has permitted investigation of the incorporation of electro-optic materials into photonic bandgap and microresonator structures. The latter are relevant to active wavelength division multiplexing (WDM). Significant quality factors (greater than 10,000) have been realized for such devices permitting wavelength discrimination at telecommunication wavelengths of 0.01 nm.

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