11
Optical Applicationswith CST Microwave Studio
Dr. Frank Demming-Janssen
22
Outline Whats so special on optical simulations?
optics for beginners materials
Solver overview for optical simulation Application examples
33
Gradient Index
Fiber/Optics
TF/SF
Calcu
lation
2nd-Order
and 3rd
-Order nonlinear
materials
Plasm
onGauss
Beam
n and
k
Fresnel equations
44
n and k
are called the refractive index and extinction coefficient
nkkn
inkinn
im
re
2
)1(22
=
=
+=+=
)
optical user will ALWAYS use these parameters
+= inn)
*
* sometimes:
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Calculate Drude Parameter Macro
66 www.cst.com
Optical WG Modes with CST MWS
n = 1.45n = 1.16
a = 500 nm
Freq: 330 THz -> 909 nm wavelength
a
optical_wg_sweep.zip
77 www.cst.com
21
2/nn
nkb o
=
( )212221 nnakV o =
Theoretical Dispersion Plot
*G.P. Agrawal: Fiber Optics Communication Systems, Wiley Series in Microwave and Optical Engineering, pp 34
With:
88 www.cst.com
Modes
HE11
HE12
99 www.cst.com
Modedispersion Mode 1
Error calculation: Because of the use of the normalized propagation const. b the
error in this curve seems larger then it is! An error of less the 1% in the might show up as a error of more then 5% in b!
1010 www.cst.com
Modedispersion Higher Order modes
1111
Plasmon
1212
Materials
For metals the real part of eps is NOT negligible and is negative and dispersive!
1313
CST MICROWAVE STUDIO
periodic boundaries (unit cells) Dispersion diagramsEigenmode
periodic structures with Floquet port modes unit cells surface plasmons
TET mesh accurate field solutions at dielectric/Drude metal interface
Frequency Domain
Large Problems Memory efficient algorithm Hardware Accelerator, Cluster Computing
Perfect Boundary approximation eliminates staircase error at dielectric/dielectric and
dielectric/PEC interface Broadband Solution
Broadband Farfield Monitor
Transient
Solver Overview Optical Applications
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Transient Solver- advantages -
Memory efficient algorithm solves electrical large problems
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Transient Solver- advantages -
Memory efficient algorithm Perfect Boundary Approximation
eliminates staircase error at dielectric/dielectric and dielectric/PEC interface
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Transient Solver- advantages -
Memory efficient algorithm Perfect Boundary Approximation Calculates Broadband Solution
Coated Silica Sphere
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Transient Solver- some weaknesses -
Local Field Error (Drude Material)
PBA works only perfect on normal dielectric materials. On Drude materials with a sign change of real par of at
interface PBA has no effect only affect local field values
MWS FDTD from publication
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Frequency Domain Solver- advantages -
TET and HEX mesh TET mesh resolves material interfaces: Accurate local field
information for Drude Materials
HEX TET
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Frequency Domain Solver- advantages -
TET and HEX mesh TET mesh resolves material interfaces: Accurate local field
information for Drude Materials
Fields along line across material interfaceHEX TET
2020
Example: Nanometric Optical Tweezers
EP
metal tip
dielectric Sphere: 5 nm radius
Reference: Lukas Novotny, Randy X. Bian, and X. Sunney Xie,
Physical Review Letters, Volume 79, No. 4, 28 July 1997 Acrobat-Dokument
2121
Field enhancement
E
P
EP
Polarization of the incident E-field aligned with tip axis: enhancement factor 75
Polarization of the incident E-fieldperpendicular to the tip axis:
no enhancement
Incident field = 810 nm
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Trapping a particle underneath the tip
Trapped dielectric particle
Trapped metallic particle
Incident field = 810 nm
2323
Frequency Domain Solver- advantages -
TET and HEX mesh Periodic and Unit cell calculation
Allows arbitrary angle of incidents for plane waves
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Example: Frustrated Total Reflection
Power Flow vs. Gap Width
Transmission vs. Gap Width
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Example: Surface Plasmon Generation
EP
metal sheet50 nm
Incident field phi > phi critical
= 2.56
= 1.69
= -15.99 + 0.8i
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Example: Surface Plasmon Generation
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Example: Plasmon Scattering
EP
Grating distance
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Example: Plasmon scattering by gradingscattered field
EP
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Example: Plasmon excitation by grading
EP
Grating distance
Surface Plasmon
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Example: Plasmon excitation by grading- structure setup -
2 D Solution setup only 1 mesh cell in
height Periodic Boundaries Ports at both ends
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Example: Plasmon excitation by grading- structure setup -
record balance: Energy absorb by system
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Example: Plasmon excitation by gradingTD Simulation
grating
550 THz
450 THz
3333
Frequency Domain Solver- advantages -
TET and HEX mesh Periodic and Unit cell calculation Arbitrary material dispersion
For FD Solver ignore warning concerning material fit
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Example: Scattering on a coated sphere
Test vehicle: nano shell - silver coated silica
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Results: Extinction Cross Section
MWS: different solversPublished results
3636
Thank you
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