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:

55

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

1414

Transient Solver- advantages -

Memory efficient algorithm solves electrical large problems

1515

Transient Solver- advantages -

Memory efficient algorithm Perfect Boundary Approximation

eliminates staircase error at dielectric/dielectric and dielectric/PEC interface

1616

Transient Solver- advantages -

Memory efficient algorithm Perfect Boundary Approximation Calculates Broadband Solution

Coated Silica Sphere

1717

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

1818

Frequency Domain Solver- advantages -

TET and HEX mesh TET mesh resolves material interfaces: Accurate local field

information for Drude Materials

HEX TET

1919

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

2222

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

2424

Example: Frustrated Total Reflection

Power Flow vs. Gap Width

Transmission vs. Gap Width

2525

Example: Surface Plasmon Generation

EP

metal sheet50 nm

Incident field phi > phi critical

= 2.56

= 1.69

= -15.99 + 0.8i

2626

Example: Surface Plasmon Generation

2727

Example: Plasmon Scattering

EP

Grating distance

2828

Example: Plasmon scattering by gradingscattered field

EP

2929

Example: Plasmon excitation by grading

EP

Grating distance

Surface Plasmon

3030

Example: Plasmon excitation by grading- structure setup -

2 D Solution setup only 1 mesh cell in

height Periodic Boundaries Ports at both ends

3131

Example: Plasmon excitation by grading- structure setup -

record balance: Energy absorb by system

3232

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

3434

Example: Scattering on a coated sphere

Test vehicle: nano shell - silver coated silica

3535

Results: Extinction Cross Section

MWS: different solversPublished results

3636

Thank you