Characterization of Photonic Structures with CST Microwave Studio

Stefan Prorok, Jan Hendrik Wülbern, Jan Hampe, Hooi Sing Lee, Al d P t d M f d Ei hAlexander Petrov and Manfred Eich

Hamburg University of Technology, Institute of Optical and Electronic Materials

CST UGM 2010

p

Hamburg University of Technology Institute of Optical and Electronic Materials, Eich

Darmstadt

1. Overview1. Overview

2. Ring Resonators

3. 3D Photonic Crystals

4. 2D Photonic Crystals

5. Summary5 Su a y

Hamburg University of Technology Institute of Optical and Electronic Materials, Eich2

A wide range of topics is covered by our instituteCURRENT RESEARCH TOPICSCURRENT RESEARCH TOPICS

Waveguides:• Four-wave mixing

Ring resonators:• Tunable filters

g• Gyrotropic waveguides

2D Photonic crystals:

• Optical circulators• Electrooptical modulation2D Photonic crystals:• Slow light• Strong light confinement, high Q cavities (Q > 1e6)• Electrooptical modulation

3D Photonic crystals:• Thermal barrier coatings

Th h t lt i

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• Thermophotovoltaic

Strip waveguides and slotted waveguides serve as basic building blocks for integrated photonic devicesg g pE-FIELD PATTERN OF STRIP AND SLOT WAVEGUIDES

Strip waveguide Slot waveguide

y

Strip waveguide Slot waveguide

Polymer Polymer

xSi Si Si

q-TM q-TE

BOX BOX

• SOI wafers with 2 qEy-component Ex-component

qSOI wafers with 2 µm bouried oxide

• 220 nm silicon core. • Polymer cladding

Hamburg University of Technology Institute of Optical and Electronic Materials, Eich4

y g

1. Overview1. Overview

2. Ring Resonators

3. 3D Photonic Crystals

4. 2D Photonic Crystals

5. Summary5 Su a y

Hamburg University of Technology Institute of Optical and Electronic Materials, Eich5

Slotted waveguides can be used to build highly resonant structuresNORMAL H-FIELD COMPONENT AND RADIAL E-FIELD COMPONENT OF A RING RESONATOR AT RESONANCE

Polymer

Logarithmic Hy field

Logarithmic Er field

BOX

Normal H-field and radial E-field of ring resonator at resonance

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Quality factor can be extracted from the E-field intensity spectrum in the ringp gE-FIELD INTENSITY IN THE RING FROM CST SIMULATION

190

180

185

190

V/m

]

Q~2700

175

180

ensi

ty [d

B V

165

170

E-fi

eld

Inte

1590 1595 1600 1605 1610 1615 1620155

160

Hamburg University of Technology Institute of Optical and Electronic Materials, Eich7

Wavelength [nm]

Complete resonator including segmented part for electrical contact was simulated

0

SIMULATION AND EXPERIMENTAL RESULTS

400 nmPolymer

8

-4 Simulation ExperimentdB

] 220 nm

y

Si

-12

-8

smis

sion

[

InputSiO2x

TM mode

-20

-16

Tran

s

190,8 190,9 191,0 191,1 191,2 191,3 19-24

Frequency [THz]

Output x y

z

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Frequency [THz]

1. Overview1. Overview

2. Ring Resonators

3. 3D Photonic Crystals

4. 2D Photonic Crystals

5. Summary5 Su a y

Hamburg University of Technology Institute of Optical and Electronic Materials, Eich9

3D photonic crystal structures can be used as efficient infrared reflectorsCONCEPT FOR THERMAL BARRIER COATINGS

Self assembled di l t i h H t fl tidielectric spheres Heat reflection

• High reflectivity for infrared radiation• Low thermal conductivity

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Inverse structure provides a wider bandgap and greater suppression than the direct opalpp pTRANSMISSION SPECTRA OF DIRECT & INVERSE OPAL STRUCTURE

Δn =2.1210 layers

Inverse opalDi t l

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Inverse opalDirect opal

Hemispherical broadband illumination of multilayer structure can be simulatedAPPLICATION OF DIFFERENT CST MWS SOLVERS FOR 3D PhC

y

Infinite FCC

Single stack normal & angle incidence

Multistack incl.defects

lattice,

Periodic boundryboundry

Nickel alloy

Eigenmode Frequency domain solver Time

Frequency domain solver, Time domain solvers

y

Hamburg University of Technology Institute of Optical and Electronic Materials, Eich12

Eigenmode solver

Frequency domain solver, Time domain solvers

Experimental results are shifted by 3 % due to deviations in the diameter of spheresdeviations in the diameter of spheresTRANSMISSION SPECTRA OF SIMULATION & MEASUREMENT

λ center = 922 nm r ~ 180nmλ center = 922 nm

FWHM = 112 nm

λ center = 950 nm

FWHM = 90 nm Simulation: 10 layers

Measurement: ~ 60 layers

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1. Overview1. Overview

2. Ring Resonators

3. 3D Photonic Crystals

4. 2D Photonic Crystals

5. Summary5 Su a y

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Symmetry planes are used to reduce the simulation volumevolumeMODEL FOR A 2-D POINT DEFECT CAVITY IN A HEXAGONAL LATTICE EXCITED BY A DISCRETE PORT

CST MWS model with symmetry planes and boundary conditions

Normal H-field distribution inside the cavity at resonance frequency

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planes and boundary conditions the cavity at resonance frequency

AR-filter can reduce the simulation time in highly resonant structures significantlyresonant structures significantlyENERGY DECAY IN TRANSIENT SIMULATION AND H-FIELD MAGNITUDE

AR-filter is used to compensate for truncation errors in prematurely aborted transient simulations

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in prematurely aborted transient simulations

CST reproduces previously reported results on PhC heterostructure cavities

CST MODEL AND RESULTS FOR HETEROSTRUCTURE CAVITY

Asano:*Asano:QSim= 2*106

νres = 191.0 THzC

CST:QEng= 2.1*106

QAR = 1.9*106

νres = 192.8 THz

N20,6

0,8

1,0

d [a

.u]

Sim parameters:C = 12a, N2 = 20a152,950 Meshcellst 20 192 750 192 752 192 754 192 756 192 758 192 760

0,0

0,2

0,4

Pro

be F

iel

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*Asano et al., IEEE Jour. of Sel. Top. in Quan. Elec., 2006tSim = 20 pstComp = 1h 50 min

192,750 192,752 192,754 192,756 192,758 192,760

frequency [THz]

A slotted PhC heterostructure cavity incl. injector and coupler sections was realizedpDESIGN AND SEM OF A SLOTTED PHC HETEROSTRUCTURE CAVITY

Cavity ReflectorReflectorInjector Injector

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Fabrication by HHI and TU Berlin

Resonance with Q = 2600 has been observed in a NLO-polymer infiltrated slotted PhC heterostructure p yTRANSMISSION OF A SLOTTED PHC HETEROSTRUCTURE CAVITY

0.5

0.4

a.u.

] Q = 2600λ = 1545 16 nm

0.2

0.3

smis

sion

[a λ0 = 1545.16 nmΔλ = 0.58 nm

0.1Tran

s

1540 1544 15480.0

Wavelength [nm]Fabrication by HHI and TU Berlin

Hamburg University of Technology Institute of Optical and Electronic Materials, Eich19

Fabrication by HHI and TU Berlin

Wülbern, Eich et al., Opt. Exp. 17, (2009)

Slotted cavity increases sensitivity to index changesRESONANCE SPECTRA AT MODIFIED REFRACTIVE INDICIESRESONANCE SPECTRA AT MODIFIED REFRACTIVE INDICIES

TE-Polarization-> Δn = 0 5n3r13E> Δn 0.5n r13E-> Δn = 0.001 => U < 1 V

r33 = 100 pm/V

d = 3µmd 3µm

Wslot = 150 nm

Δn = 0.001 => Δν = 40 GHz, Δλ = 0.32 nm

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Photonic crystal provides optical isolation and electrical contact for 100 GHz EO modulation bandwidthSLOTTED PhC EQUIVALTENT RF CIRCUIT cm1.0 Ω=ρ

lFdWR SiSislot /ρ≈

slotSipolyslot WldnC /20ε= slotSipolyslot 0

with (Ndoping = 1017 cm-3)*cm1.0 Ω=ρ

GHz100)22/(13 ≈⋅= slotslotdB CRf π

Umod < 1V for r33 = 100 pm/V

Losses due to doping: ~ 2 dB/cm(Soref et al., IEEE JQE. 23, 1987)

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Wülbern, Eich et al., Opt. Exp. 17, (2009)

First realization of modulator with 40 GHz bandwidth and µm footprint µ pMODULATION SIDE BANDS IN OPTICAL SPECTRUM

-50

-40

Bm]

30 GHz 40 GHz

-50

-40

Bm]

15 GHz 20 GHz

-70

-60

ical

Pow

er [d

B

-70

-60

ical

Pow

er [d

B

-40 -20 0 20 40

-90

-80Opt

i-30 -20 -10 0 10 20 30

-90

-80Opt

i

Frequency [GHz]Frequency [GHz]

Hamburg University of Technology Institute of Optical and Electronic Materials, Eich22

Wülbern et al., APL (submitted)

1. Overview1. Overview

2. Ring Resonators

3. 3D Photonic Crystals

4. 2D Photonic Crystals

5. Summary5 Su a y

Hamburg University of Technology Institute of Optical and Electronic Materials, Eich23

Summary

• Simulation of strip and slot waveguides with CST MWS has• Simulation of strip and slot waveguides with CST MWS has been shown

• Q-factor extraction from time domain simulations isQ factor extraction from time domain simulations is demonstrated for ring resonators and 2D photonic crystals

• Frequency solver is used to determine angle dependent q y g ptransmission spectra of 3D photonic crystals

• A photonic crystal cavity for GHz amplitude modulation is discussed

Hamburg University of Technology Institute of Optical and Electronic Materials, Eich24