Download presentation

Presentation is loading. Please wait.

Published byJason Pardon Modified over 2 years ago

1
The split operator numerical solution of Maxwell’s equations Q. Su Intense Laser Physics Theory Unit Illinois State University LPHY 2000Bordeaux FranceJuly 2000 Acknowledgements: E. Gratton, M. Wolf, V. Toronov NSF, Research Co, NCSA S. Mandel R. Grobe H. Wanare G. Rutherford

2
Electromagnetic wave Maxwell’s eqns Light scattering in random media Photon density wave Boltzmann eqn Photon diffusion Diffusion eqn

3
Outline Split operator solution of Maxwell’s eqns Applications simple optics Fresnel coefficients transmission for FTIR random medium scattering Photon density wave solution of Boltzmann eqn diffusion and P 1 approximations Outlook

4
Numerical algorithms for Maxwell’s eqns Frequency domain methods Time domain methodsU(t->t+ t) Finite difference A. Taflove, Computational Electrodynamics (Artech House, Boston, 1995) Split operator J. Braun, Q. Su, R. Grobe, Phys. Rev. A 59, 604 (1999) U. W. Rathe, P. Sanders, P.L. Knight, Parallel Computing 25, 525 (1999)

5
Exact numerical simulation of Maxwell’s Equations Initial pulse satisfies : Time evolution given by :

6
Split-Operator Technique Effect of vacuum Effect of medium

7
and Numerical implementation of evolution in Fourier space where Reference: “Numerical solution of the time-dependent Maxwell’s equations for random dielectric media” - W. Harshawardhan, Q.Su and R.Grobe, submitted to Physical Review E

8
n1n1 n2n2 -101005-5 0 10 -10 0 -5 5 z/ y/ First tests : Snell’s law and Fresnel coefficients Refraction at air-glass interface

9
Fresnel Coefficient

10
d n 1 s n 2 n 1 Second test Tunneling due to frustrated total internal reflection

11
Amplitude Transmission Coefficient vs Barrier Thickness

12
Light interaction with random dielectric spheroids Microscopic realization Time resolved treatment Obtain field distribution at every point in space 400 ellipsoidal dielectric scatterers Random radii range [0.3, 0.7 ] Random refractive indices [1.1,1.5] Input - Gaussian pulse One specific realization

13
20 0 10 -10 0 10 -10 y/ -20 z/ T = 8T = 16 T = 24 T = 40

14
Summary - 1 Developed a new algorithm to produce exact spatio- temporal solutions of the Maxwell’s equations Technique can be applied to obtain real-time evolution of the fields in any complicated inhomogeneous medium »All near field effects arising due to phase are included Tool to test the validity of the Boltzmann equation and the traditional diffusion approximation

15
Photon density wave Infrared carrier penetration but incoherent due to diffusion Modulated wave 100 MHz ~ GHz maintain coherence tumor Input light Output light D.A. Boas, M.A. O’Leary, B. Chance, A.G. Yodh, Phys. Rev. E 47, R2999, (1993)

16
Boltzmann Equation for photon density wave J.B. Fishkin, S. Fantini, M.J. VandeVen, and E. Gratton, Phys. Rev. E 53, 2307 (1996) Q: How do diffusion and Boltzmann theories compare? Studied diffusion approximation and P 1 approximation

17
Bi-directional scattering phase function Mie cross-section: L. Reynolds, C. Johnson, A. Ishimaru, Appl. Opt. 15, 2059 (1976) Henyey Greenstein: L.G. Henyey, J.L. Greenstein, Astrophys. J. 93, 70 (1941) Eddington: J.H. Joseph, W.J. Wiscombe, J.A. Weinman, J. Atomos. Sci. 33, 2452 (1976) Other phase functions Diffusion approximation

18
Incident: — Transmitted: — Diffusion: — Solution of Boltzmann equation

19
J.B. Fishkin, S. Fantini, M.J. VandeVen, and E. Gratton, Phys. Rev. E 53, 2307 (1996) Confirmed behavior obtained in P 1 approx Exact Boltzmann: — Diffusion approximation: — Frequency responses reflected transmitted

20
Photon density wave Right going Left going Exact Boltzmann: — Diffusion approximation: —

21
Resonances at w = n /2 (n = integer) Exact Boltzmann: — Diffusion approximation: —

22
Summary Numerical Maxwell, Boltzmann equations obtained Near field solution for random medium scattering Direct comparison: Boltzmann and diffusion theories Outlook Maxwell to Boltzmann / Diffusion? Inverse problem? www.phy.ilstu.edu/ILP

Similar presentations

OK

Relativistic nonlinear optics in laser-plasma interaction Institute of Atomic and Molecular Sciences Academia Sinica, Taiwan National Central University,

Relativistic nonlinear optics in laser-plasma interaction Institute of Atomic and Molecular Sciences Academia Sinica, Taiwan National Central University,

© 2017 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Ppt on cross-sectional study meaning Ppt on standing order template Ppt on spices and herbs Ppt on astronomy and astrophysics encyclopedia Ppt on organised retailing in india Ppt on conservation of environment project Ppt on trade fair circular Ppt on bill of lading Ppt on model view controller python Ppt on introduction to object-oriented programming python