Characterization of Photonic Structures with
CST Microwave Studio
Stefan Prorok, Jan Hendrik Wülbern, Jan Hampe, Hooi Sing Lee,
Al
Alexander
d P
Petrov
t
and
dM
Manfred
f d Ei
Eich
h
Hamburg University of Technology,
p
and Electronic Materials
Institute of Optical
CST UGM 2010
Darmstadt
Hamburg University of Technology
Institute of Optical and Electronic Materials, Eich
1. Overview
2. Ring Resonators
3. 3D Photonic Crystals
4. 2D Photonic Crystals
5. Su
5
Summary
ay
Hamburg University of Technology
2
Institute of Optical and Electronic Materials, Eich
A wide range of topics is covered by our institute
CURRENT RESEARCH TOPICS
Waveguides:
• Four-wave mixing
g
• Gyrotropic waveguides
Ring resonators:
• Tunable filters
• Optical circulators
• Electrooptical modulation
2D Photonic crystals:
• Slow light
• Strong light confinement, high Q cavities (Q > 1e6)
• Electrooptical modulation
3D Photonic crystals:
• Thermal barrier coatings
• Thermophotovoltaic
Th
h t
lt i
Hamburg University of Technology
3
Institute of Optical and Electronic Materials, Eich
Strip waveguides and slotted waveguides serve as basic
building
g blocks for integrated
g
photonic
p
devices
E-FIELD PATTERN OF STRIP AND SLOT WAVEGUIDES
Strip waveguide
Slot waveguide
Polymer
Polymer
y
x
Si
Si
BOX
BOX
• SOI wafers with 2
µm bouried oxide
• 220 nm silicon core.
y
cladding
g
• Polymer
Hamburg University of Technology
Si
q
q-TM
Ey-component
4
q
q-TE
Ex-component
Institute of Optical and Electronic Materials, Eich
1. Overview
2. Ring Resonators
3. 3D Photonic Crystals
4. 2D Photonic Crystals
5. Su
5
Summary
ay
Hamburg University of Technology
5
Institute of Optical and Electronic Materials, Eich
Slotted waveguides can be used to build highly resonant
structures
NORMAL H-FIELD COMPONENT AND RADIAL E-FIELD COMPONENT
OF A RING RESONATOR AT RESONANCE
Polymer
Logarithmic Er field
Logarithmic Hy field
BOX
Normal H-field and radial E-field
of ring resonator at resonance
Hamburg University of Technology
6
Institute of Optical and Electronic Materials, Eich
Quality factor can be extracted from the E-field intensity
spectrum
p
in the ring
g
E-FIELD INTENSITY IN THE RING FROM CST SIMULATION
190
Q~2700
E-field Inte
ensity [dB V
V/m]
185
180
175
170
165
160
155
1590
1595
Hamburg University of Technology
1600
1605
1610
Wavelength [nm]
7
1615
1620
Institute of Optical and Electronic Materials, Eich
Complete resonator including segmented part for
electrical contact was simulated
SIMULATION AND EXPERIMENTAL RESULTS
Polymer
0
Trans
smission [dB]
-4
Simulation
Experiment
8
-8
Si
220 nm
y
x
Input
-12
400 nm
SiO2
TM mode
-16
-20
Output
-24
190,8
190,9
191,0
191,1
191,2
y
x
191,3
19
z
Frequency [THz]
Hamburg University of Technology
8
Institute of Optical and Electronic Materials, Eich
1. Overview
2. Ring Resonators
3. 3D Photonic Crystals
4. 2D Photonic Crystals
5. Su
5
Summary
ay
Hamburg University of Technology
9
Institute of Optical and Electronic Materials, Eich
3D photonic crystal structures can be used as
efficient infrared reflectors
CONCEPT FOR THERMAL BARRIER COATINGS
Self assembled
di l t i spheres
dielectric
h
H t reflection
Heat
fl ti
• High reflectivity for infrared radiation
• Low thermal conductivity
Hamburg University of Technology
10
Institute of Optical and Electronic Materials, Eich
Inverse structure provides a wider bandgap and greater
suppression
pp
than the direct opal
p
TRANSMISSION SPECTRA OF DIRECT & INVERSE OPAL STRUCTURE
Δn =2.12
10 layers
Di t opall
Direct
Hamburg University of Technology
11
Inverse opal
Institute of Optical and Electronic Materials, Eich
Hemispherical broadband illumination of
multilayer
y structure can be simulated
APPLICATION OF DIFFERENT CST MWS SOLVERS FOR 3D PhC
Infinite
FCC
lattice,
Single stack normal & angle
incidence
Multistack incl.
defects
Periodic
boundry
Nickel alloyy
Eigenmode
solver
Frequency domain solver, Time
domain solvers
Frequency domain solver,
solver Time
domain solvers
Hamburg University of Technology
12
Institute of Optical and Electronic Materials, Eich
Experimental results are shifted by 3 % due to
deviations in the diameter of spheres
TRANSMISSION SPECTRA OF SIMULATION & MEASUREMENT
λ center = 922 nm
r ~ 180nm
FWHM = 112 nm
λ center = 950 nm
FWHM = 90 nm
Simulation: 10 layers
Measurement: ~ 60 layers
Hamburg University of Technology
13
Institute of Optical and Electronic Materials, Eich
1. Overview
2. Ring Resonators
3. 3D Photonic Crystals
4. 2D Photonic Crystals
5. Su
5
Summary
ay
Hamburg University of Technology
14
Institute of Optical and Electronic Materials, Eich
Symmetry planes are used to reduce the simulation
volume
MODEL 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
Hamburg University of Technology
Normal H-field distribution inside
the cavity at resonance frequency
15
Institute of Optical and Electronic Materials, Eich
AR-filter can reduce the simulation time in highly
resonant structures significantly
ENERGY DECAY IN TRANSIENT SIMULATION AND H-FIELD
MAGNITUDE
AR-filter is used to compensate for truncation errors
in prematurely aborted transient simulations
Hamburg University of Technology
16
Institute of Optical and Electronic Materials, Eich
CST reproduces previously reported results on PhC
heterostructure cavities
CST MODEL AND RESULTS FOR HETEROSTRUCTURE CAVITY
Asano:*
QSim= 2*106
νres = 191.0 THz
C
CST:
QEng= 2.1*106
QAR = 1.9*106
νres = 192.8 THz
1,0
N2
Probe Field [a.u]
0,8
0,6
Sim parameters:
C = 12a, N2 = 20a
152,950 Meshcells
tSim = 20 ps
frequency [THz]
tComp = 1h 50 min
*Asano et al., IEEE Jour. of Sel. Top. in Quan. Elec., 2006
0,4
0,2
0,0
192 750
192,750
Hamburg University of Technology
17
192 752
192,752
192 754
192,754
192 756
192,756
192 758
192,758
192 760
192,760
Institute of Optical and Electronic Materials, Eich
A slotted PhC heterostructure cavity incl. injector and
coupler
p sections was realized
DESIGN AND SEM OF A SLOTTED PHC HETEROSTRUCTURE CAVITY
Injector
Reflector
Cavity
Reflector
Injector
Fabrication by HHI and TU Berlin
Hamburg University of Technology
18
Institute of Optical and Electronic Materials, Eich
Resonance with Q = 2600 has been observed in a NLOpolymer
p
y
infiltrated slotted PhC heterostructure
TRANSMISSION OF A SLOTTED PHC HETEROSTRUCTURE CAVITY
Trans
smission [a
a.u.]
0.5
0.4
Q = 2600
λ0 = 1545.16
1545 16 nm
0.3
Δλ = 0.58 nm
0.2
0.1
0.0
1540
1544
1548
Wavelength [nm]
Fabrication by HHI and TU Berlin
Wülbern, Eich et al., Opt. Exp. 17, (2009)
Hamburg University of Technology
19
Institute of Optical and Electronic Materials, Eich
Slotted cavity increases sensitivity to index changes
RESONANCE SPECTRA AT MODIFIED REFRACTIVE INDICIES
TE-Polarization
->
> Δn = 0.5n
0 5n3r13E
-> Δn = 0.001 => U < 1 V
r33 = 100 pm/V
d = 3µm
Wslot = 150 nm
Δn = 0.001 => Δν = 40 GHz, Δλ = 0.32 nm
Hamburg University of Technology
20
Institute of Optical and Electronic Materials, Eich
Photonic crystal provides optical isolation and electrical
contact for 100 GHz EO modulation bandwidth
SLOTTED PhC EQUIVALTENT RF CIRCUIT
ρ
=
0
.
1
Ω
cm
Rslot ≈ WSi ρ / Fd Si l
C slot = ε 0 n 2poly d Si l / Wslot
with ρ = 0.1 Ωcm (Ndoping = 1017 cm-3)*
f 3dB = 1 /( 2π ⋅ 2 Rslot C slot ) ≈ 100 GHz
Umod < 1V for r33 = 100 pm/V
Losses due to doping: ~ 2 dB/cm
(Soref et al., IEEE JQE. 23, 1987)
Wülbern, Eich et al., Opt. Exp. 17, (2009)
Hamburg University of Technology
21
Institute of Optical and Electronic Materials, Eich
First realization of modulator with 40 GHz bandwidth and
µm footprint
µ
p
MODULATION SIDE BANDS IN OPTICAL SPECTRUM
15 GHz
20 GHz
-50
-60
-70
-80
-40
Optiical Power [dB
Bm]
Optiical Power [dB
Bm]
-40
-90
-30
30 GHz
40 GHz
-50
-60
-70
-80
-90
-20
-10
0
10
20
30
-40
Frequency [GHz]
-20
0
20
40
Frequency [GHz]
Wülbern et al., APL (submitted)
Hamburg University of Technology
22
Institute of Optical and Electronic Materials, Eich
1. Overview
2. Ring Resonators
3. 3D Photonic Crystals
4. 2D Photonic Crystals
5. Su
5
Summary
ay
Hamburg University of Technology
23
Institute of Optical and Electronic Materials, Eich
Summary
• Simulation of strip and slot waveguides with CST MWS has
been shown
• Q-factor
Q factor extraction from time domain simulations is
demonstrated for ring resonators and 2D photonic crystals
• Frequency
q
y solver is used to determine angle
g dependent
p
transmission spectra of 3D photonic crystals
• A photonic crystal cavity for GHz amplitude modulation is
discussed
Hamburg University of Technology
24
Institute of Optical and Electronic Materials, Eich