Dr. Arje Nachman presents an overview of his program, Electromagnetics, at the AFOSR 2013 Spring Review. At this review, Program Officers from AFOSR Technical Divisions will present briefings that highlight basic research programs beneficial to the Air Force.

Published on: **Mar 3, 2016**

Published in:
Technology

- 1. 1DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution15 February 2013 Integrity Service Excellence Dr. Arje Nachman Program Officer AFOSR/RTB Air Force Research Laboratory ELECTROMAGNETICS 5 March 2013
- 2. 2DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution 2013 AFOSR SPRING REVIEW 3001K PORTFOLIO OVERVIEW NAME: Dr. Arje Nachman BRIEF DESCRIPTION OF PORTFOLIO: Interrogation (Modeling/Simulation) of Linear/Nonlinear Maxwell’s Equations LIST SUB-AREAS IN PORTFOLIO: Theoretical Nonlinear Optics Wave Propagation Through Complex Media Fundamentals of Antenna Design/Operation Fundamentals of Effects of EM Exposure on Circuitry
- 3. 3DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Scientific Challenges • Nonlinear Optics Fundamental modeling/simulation research which addresses concerns with femtosecond filament arrangements and plasma channel characteristics. Advances in modeling/simulation of fiber and solid state lasers (with new BRI emphasis on nonequilibrium carrier distributions) to guide the development of compact, high energy systems. • RF Effects on Circuitry Identification of waveforms which produce various realizations of circuit upset (includes chaos)—See front page of 17 Dec 2012 Defense News. Complicated by the fact that effects are likely to be dictated by the activity of the circuit (eg, routines being run by laptop).
- 4. 4DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Scientific Challenges • Wave Propagation Through Complex Media Increased emphasis on imaging through Random/Turbulent media Also ongoing research provides optimism regarding a class of composite magnetic materials displaying significantly reduced losses • Antenna Design/Operation Suitable PARTNERSHIPS of MATERIALS and GEOMETRY can deliver man-made composites which exhibit novel EM attributes. Such METAMATERIALS include: NIMs, PBGs, “Unidirectional” composites, and P-T Symmetric media (new MURI). Growing reliance on small UAVs drives the need to miniaturize antennas and make them more responsive.
- 5. 5DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution MURIs This portfolio has an existing MURI called “Ultrashort Laser Pulses” (co-managed with Dr. Riq Parra) at the 2.5 year mark Dr Moloney (MURI PI) organized/hosted biannual int’l USLP conference (COFIL) A second MURI (co-managed with Dr. John Luginsland) called “High Power, Low-Loss, Artificial Materials for Transformational Electromagnetics” began September 2012 A third MURI (co-managed with Dr. Charles Lee) on “Photonic Synthetic Matter” emphasizes P-T Symmetry
- 6. 6DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Optimization of the number & configuration of the multi-static measuring array is a subject for future investigation The dots represent the positions of the transmitters and receivers on the measurement array. Section of canopy (a dielectric) Due to parts of the canopy being exposed to different amounts of ultraviolet radiation, the electric permittivity in general depends on position. Transmission Eigenvalues Drs. Colton, Cakoni and Monk – Math/Univ. of Delaware
- 7. 7DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution An incident wave Ei with wave number k>0 is scattered by an anisotropic dielectric with support D, with relative electric permittivity , 3<|N(x)|<10 and constant magnetic permeability . is the frequency Transmission Eigenvalues The Scattering Problem
- 8. 8DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Assume Ei(x) given and the far field pattern of the scattered field is defined by Assume that D known: want to obtain information about N(x). To this end we solve the far field equation for g where z ϵ D and q is a vector for the polarization of the rhs dipole in R3. Transmission Eigenvalue Solution d is the direction of incident field
- 9. 9DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution If k isn’t a transmission eigenvalue, a bounded solution g of the far field equation can be found. At a transmission eigenvalue, the solution g of the far field equation is very large. By plotting the L2-norm of g vs the wave number k, we can determine the transmission eigenvalues. Since transmission eigenvalues defined via a system of PDEs involve the permittivity tensor N(x), the eigenvalues contain information on this tensor. Transmission Eigenvalues Determination of Transmission Eigenvalues
- 10. 10DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Red dots indicate exact transmission eigenvalues. Peaks in the norm of g indicate transmission eigenvalues from measured data. Solving far-field equation gives peaks at the transmission eigenvalues N=16 N=5 Transmission Eigenvalues Determination of Transmission Eigenvalues
- 11. 11DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution It was shown by Cakoni-Gintides-Haddar that transmission eigenvalues depend monotonically on the lowest eigenvalue of the relative permittivity tensor as well as on the volume of possible cavities. In 2012 Drs. Jeremy Knopp and Adam Cooney from AFRL/RX (the Materials Directorate) awarded a contract to my PIs at the University of Delaware to investigate the use of transmission eigenvalues for the nondestructive testing of airplane canopies. Transmission Eigenvalues Applications to Nondestructive Testing
- 12. 12DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Traditional Scattering Problem of an Internal Defect Conducting Half-Space Problem of an Internal Defect Transmit & Receive object Buried mechanical or electromagnetic “defects” The standard problem of a transmissive object conductor Transmit & Receive object Buried mechanical or electromagnetic “defects” Object is transmissive but backed by conductor. Energy that would have been transmitted is reflected back to the single side. Think of something similar to thermal protection foam/tiles on (now retired) space shuttle. Goal of inspections: determine if protective foams/tiles are damaged or compromised. Rather than surround the entire (very large) system, localized measurements taken at each location so problem is essentially as shown above on the right. local measurement zone Future Transmission Eigenvalue Research
- 13. 13DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Localized cavity field more intense than incident field High sensitivity to parameters (e.g. incidence angle) CEM for Enclosures Dr Oscar Bruno (Math/Caltech and MathSys)
- 14. 14DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Incidence: 0 degrees
- 15. 15DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Incidence: 60 degrees
- 16. 16DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Cavity-Field Issues – Dr Bruno’s numerical solvers produce extremely accurate solutions for geometries that contain singularities (edges, corners) at all frequencies for three-dimensional problems involving non-trivial geometries. This is a unique capability: not aware of other solvers capable of producing such quality solutions. 6.1 progress being captured in user-friendly code (Phase II STTR) within AFOSR T&E program (Dr Michael Johnson/Seek Eagle) – Geometrical complexity; corner/edge resolution – Models of subsystems within enclosures – Printed circuits – Other structures and substructures (e.g., metal coated dielectrics) – Wire arrays
- 17. 17DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution OPSL Breaks 100W Milestone 0 20 40 60 80 100 120 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 OutputPower(W) Net Pump Power (W) 750um 880 um 1170 um 1170 um(0 ⁰C) Pump Diameter Cool down to 0⁰C • Quantum design enables breakthrough • Many-body theory plus thermal analysis • Fast track iteration with grower Temperature Dependent Reflectivity (Semiconductor Chip Quality Control) Output Power for Different Pump Spots HeatFlow 6 OPSL Cavity Schematic Dr Jerome Moloney - Optical Sciences and Mathematics - University of Arizona
- 18. 18DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution USPL MURI Optical filament dynamics Dr Demetrios Christodoulides/UCF An optical filament establishes itself through a balance of Kerr self-focusing and defocusing processes caused by multi-photon produced plasma. To maintain this balance the filament must expend its own energy, and as expected once its power dips below a certain threshold it eventually vanishes. Are there ways by which the longevity of a filament can be extended? Are there ways by which the longevity of a filament can be extended?
- 19. 19DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Dressed Optical Filaments Energy from the dress flows inwards to aid the filament. Filament • Power is spread over large area • Dressing beam maintains a low intensity profile: dress beam itself does not induce lasting nonlinear effects and therefore does not develop a filament during propagation Dress
- 20. 20DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution A Gaussian Dressed Filament -40 -30 -20 -10 0 10 20 30 40 0 0.2 0.4 0.6 0.8 1 1.2 1.4 I/I0 X (mm) 𝐸𝑡𝑡𝑡𝑡𝑡 𝑟, 𝑡, 𝑧 = 0 = 𝐸𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓 + 𝐸 𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺 𝑑𝑑𝑑𝑑𝑑 𝑷 𝑫,𝑮 = 𝟐𝟐 𝑷 𝒄𝒄𝒄𝒄 𝑷 𝑭 = 𝟑. 𝟑 𝑷 𝒄𝒄𝒄𝒄
- 21. 21DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Undressed Filament Propagation Iclamp≈ 7 ⋅ 1013 𝑊/𝑐𝑚2 I/I0 Z (m) ≈ 2 m Collapse point-theory
- 22. 22DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Iclamp≈ 7 ⋅ 1017 𝑊/𝑚2 Dressed Filament Propagation I/I0 Z (m) ≈ 18 m
- 23. 23DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Conclusions • The longevity of an optical filament can be extended by judiciously providing an auxiliary beam that acts as a secondary energy reservoir throughout propagation • Several questions remain: What will be an optimal dressed beam? Does it depend on the medium involved? Can one extend the filamentation process by 2-3 orders in distance?
- 24. 24DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Space Object Imaging Dr George Papanicolaou, Math/Stanford xs xq Think of a cheap Synthetic Aperture extending several kilometers High frequency radars Satellite Above tropopause
- 25. 25DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Correlation-Based Imaging in Strongly Scattering Random Media The array response matrix p(t,xr;xs) consists of the signals recorded by the rth receiver when the sth source emits a short pulse. Using the formulas below for the cross-correlation produces images as if the medium between the sources and the passive array was homogeneous and the auxiliary passive array was an active one made up of both sources and receivers. 𝑐 𝑇 𝜏, 𝑥⃗ 𝑞, 𝑥⃗ 𝑞𝑞 = � � 𝑝 𝜏, 𝑥⃗ 𝑞; 𝑥⃗ 𝑠 𝑝 𝑡 + 𝜏, 𝑥⃗ 𝑞𝑞; 𝑥⃗ 𝑠 𝑑𝑑, 𝑁𝑠 𝑠=1 𝑇 0 𝐼 𝑦⃗ 𝑆 = � 𝐶 𝑇 𝑇 𝑥⃗ 𝑞, 𝑦⃗ 𝑆 + 𝑇 𝑦⃗ 𝑆, 𝑥⃗ 𝑞 , 𝑥⃗ 𝑞, 𝑥⃗ 𝑞𝑞 𝑁 𝑞 𝑞,𝑞′=1
- 26. 26DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution ELECTROMAGNETICS LAB TASKS Dr. Brad Kramer(AFRL/RY), “Electromagnetic Materials and Antennas” Model Electromagnetically Small Antennas: superdirective, wide-band, conformal Dr. Ilya Vitebskiy (AFRL/RY) “Metamaterials for the Enhancement of Light-Matter Interaction” Performance enhancement of various transceivers Dr. Saba Mudaliar (AFRL/RY), “EM Scattering Studies” * Predict scattering from clutter and rough surfaces Dr. Kris Kim (AFRL/RY), “Predict Far-Field RCS via Near-Field Data” * (Dr.) Jason Parker (AFRL/RY), “Moving Target Radar Feature Extraction” Dr. Nicholas Usechak (AFRL/RY), “Spatial Effects in Multi-Section Semiconductor Lasers” ** Investigate control of amplitude-phase coupling in Quantum Dot laser systems Dr. Timothy Clarke (AFRL/RD), “Modeling of HPM Effects on Digital Electronics” Mathematical models predicting effects (upset) on digital electronics when exposed to various incident EM pulses Dr. Danhong Huang (AFRL/RV), “Models for Ultrafast Carrier Scattering in Semiconductors” Model IR amplifier for extremely weak signals and distant targets Dr. Analee Miranda (AFRL/RY), “Detection and Imaging of Underground Facilities Using SAR Data” Dr. Matthew Grupen (AFRL/RY), “Electronic Band Structure for High Speed Quantum Electron Device Simulation“ Modeling/Simulation of quantum tunneling devices Dr. Iyad Dajani (AFRL/RD), “Time Dynamics of SBS in Fiber Amplifiers with Frequency Modulation” SBS suppression research to realize higher power in narrow linewidth fiber amplifiers Dr. Erik Bochove (AFRL/RD) “Modeling of Large Nonlinear Passively Phased Fiber Laser Arrays” *=Renewal for FY13 **=FY13 Star Team
- 27. 27DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Connections with Other Organizations • ONR MURI (U Maryland) “Exploiting Nonlinear Dynamics for Novel Sensor Networks” managed by Dr. Michael Shlesinger, ONR I serve on this ONR MURI panel MURI (U Pennsylvania) “Negative Index Media” Attended review of ONR (Dr. Mark Spector) NIM Metamaterials MURI MURI “Random Lasers and Rogue Waves” FY13 topic from Dr. Michael Shlesinger, ONR I serve on this ONR MURI panel
- 28. 28DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution Connections with Other Organizations • ARO MURI (Univ. Central Florida) “UltraShort Laser Pulse Propagation” managed by Dr. Rich Hammond, ARO • Dr Hammond served on my FY10 USLP MURI evaluation panel and I served on his FY11 USLP MURI panel • NRO • Extensive discussions/visits regarding impact of 6.1 research on NRO needs