Transcript Integrated Magneto-Optical Isolator for Feasible Photonic

Magneto-Optic Materials for
Integrated Photonics
Bethanie J. H. Stadler
Sang-Yeob Sung, Luis Cruz, Na hyoung Kim,
Xiaoyuan Qi, Ryan Cobian, Neal Speetzen
Electrical and Computer Engineering
University of Minnesota
www.tc.umn.edu/~stadl002
Outline
Motivation (isolators)
 Garnet Layer

–
–
Fabrication
Characterization
Buffer Layers
 Permanent Magnets
 Photonic Crystals

AIMD Group
Bethanie J. H. Stadler
Current Isolators Use YIG (Y3Fe5O12)
Polarizer
Garnet Films

Laser Beam


Magnet
M
AIMD Group
Garnet
Substrate
Garnet Fabrication
– LPE requires garnet
substrates and high
temperatures.
Bulk permanent magnet
qF = V B l
V-material constant
B- magnetic field
l- pathlength
Bethanie J. H. Stadler
Integrated Isolators
Permanent Magnet Film
M
Oxide Overlayer / Compliant Layer
PM fiber
Garnet Waveguide
Buffer layer on semiconductor substrate
Device goal: waveguide isolator

Garnet Fabrication
–
–
–
–


MOCVD
MOCLD
Dual-target sputtering
Single-target sputtering
Buffer and cladding layers (MgO, SiO2)
Permanent magnet films (SmCo)
AIMD Group
Bethanie J. H. Stadler
Advantages

Fully integrating optical isolators on a single wafer
Compact size

Low cost

Low magnetic field required

No focusing optics required

Now: Optical packaging (Laser diode + Isolator)

Later: Photonic integrated circuits (PICs)

AIMD Group
Bethanie J. H. Stadler
Faraday Rotation
l1 l0
Excitation
Absorption
Absorption
l0
-
+
n-
n+
n
Dispersion
l
Without Magnetic
Field
AIMD Group
l2
n
ls
l
With Applied Magnetic
Field
Bethanie J. H. Stadler
Garnet can accommodate half the
periodic table!
dodecahedral site
octahedral site
tetrahedral site
oxygen
QF (T,l) = C(l) Mc(T) + A(l) Ma(T) + D(l) Md(T)
AIMD Group
V. J. Fratello and R. Wolfe, in Magnetic FilmBethanie
Devices,
J. H.(2000).
Stadler
Other materials
Low Verdet constants: (longer lengths or stronger magnets)
Magneto-optical glasses
oxides and fluorides with Ce3+, Pr3+, Eu2+, and Tb3+ *
rare-earth or tranisition-metal doped semiconductors
Easy to integrate with semiconductors
Potential devitrification lower films due to nonequilibrium fab
Rotations as high as –0.569 min/Oe/cm
High Absorption: (high optical loss)
Maghemite made by pulsed laser deposition at 500C **
High Faraday rotations due to octahedral Fe2+
* K. Tanaka, K. Fujita, N. Matsuoka, K. Hirao, S. Soga, J. Materials Research 13 1989 (1998)
AIMD
Stadler
**T.
Teper,Group
F. Illievski, C. Ross, R Zaman, R Ram, S Sung, B. Stadler, J. Appl. Bethanie
Phys. 93J. H.
(2003).
Outline
Motivation (isolators)
 Garnet Layer

–
–
Fabrication
Characterization
Buffer Layers
 Permanent Magnets
 Photonic Crystals

AIMD Group
Bethanie J. H. Stadler
Metalorganic Chemical Vapor
Deposition (MOCVD)
Heater
To Pump
By pass
line
Substrates
Vaporizer
Ar
Growth line
Table I: MOCVD Processing of
Ce:YIG
Substrate Temperature 600-700 C
Reactor Pressure
2-5Torr
Oxygen Flow Rate
300-700sccm
Nitrous Oxide Flow Rate0-500sccm
Argon Flow Rate
50 sccm
Vaporizer Temperature 230 C
Solution Flow Rate
5 ml/hr
AIMD Group
Liquid Pump
N2O O2
Y-, Fe-, Ce-(thd)*
*(2,2,6,6-tetramethyl1,3,5-heptanedionate)
Collaboration w/ Boston Applied Technologies
Bethanie J. H. Stadler
Metalorganic Chemical Liquid
Deposition (MOCLD)
Motor&
Gear Set
450 oC
Vertical
Tube
Furnace
Dipping &
Drying Chamber
Solution Dispenser
Precursors: Y(NO3)3 and Fe(NO3)3 in water/ethanol
AIMD Group
Collaboration w/ Boston Applied Technologies
Bethanie J. H. Stadler
Specialized Fabrication Potential:
Partial Pressure Differential
H2O, RF Power,
Ar
All gases conventionally
fed in at same location
Rotating substrate holder
to LN2 trap
& pump
AIMD Group
O2
Bethanie J. H. Stadler
Outline
Motivation (isolators)
 Garnet Layer

–
–
Fabrication
Characterization
Buffer Layers
 Permanent Magnets
 Photonic Crystals

AIMD Group
Bethanie J. H. Stadler
Composition- MO techniques
Table II: Sample Information
Sample Name
YIG28 (111)
YIG29
YIG 30
YIG36
YIG51



Thickness
(m)
0.38
0.25
1.9
1.38
0.51
%Ce on Y site
39
37
27
40
54
Simply add dopant to precursor in MOCVD.
Nonequilibrium techniques allows high dopant level.
Y1.5Bi1.5Fe3.8Al1.2O12 was grown by MOCLD.
AIMD Group
Bethanie J. H. Stadler
Intensity (arb. units)
20
10
20
25
n
s
s
n
30
35
2 Theta
AIMD Group
40
50
s
s
0
45
50
20
H
25
30
H
431
420 (100)
35
40
MgO Substrate
MgO Substrate
422 (44)
H
45
50
2 Theta
1000
Garnet: Y3Fe5O12

800
s
20
25
MgO Substrate
H
332
30
400
ss s
200
30
MgO Substrate
Fe-poor: Y-O, YFeO3
20
440 (30)
40
101 (100)
10
220
Intensity (arb. units)
50
Intensity (arb. units)
202 (21)
040 (20)
212 (13)
s
MgO Substrate
MgO Substrate
30
031 (5)
121 (100)
40
002 (28)
210 (12)
200 (20)
111 (50)
Effect of Composition on Structure
H
H
0
Fe-rich: Fe-O, Y2Fe4O9
600
t
u
t
t
0
35
40
45
2 Theta
Bethanie
J. H. Stadler
50
Oxygen maintains single-phase YIG
1/2 (Y2O3)
A YFeO3
Y2Fe4O9 B
Fe
Y3Fe5O12
Fe1-yO
1/2 (Fe2O3)
Fe3O4
AIMD Group
Bethanie J. H. Stadler
Sputtered/Annealed Film
Y3Fe5O12
1800
25
30
35
40
532
440
332
200
0
521
800
600
400
431
400
1400
1200
1000
422
1600
321
Intensity [Counts]
420
2000
45
50
2-Theta
AIMD Group
Bethanie J. H. Stadler
Structure of MOCLD on glass
300
Counts (arb units)
250
200
150
100
50
0
20
30
40
50
60
2 Theta

MOCLD films were dense, polycrystalline films.
AIMD Group
Bethanie J. H. Stadler
Optical Properties- Dispersion
Refractive Index
2.4
2.3
MOCLD film
2.2
MOCVD film
sputtered film
2.1
2
1
1.5
2
Wavelength (mm)
AIMD Group
Bethanie J. H. Stadler
Ce raises the index of YIG
2.4
Refractive Index
%Ce
2.3
YIG 51
YIG 28
2.2
YIG 36
2.1
YIG 30
2
1
1.5
2
Wavelength (mm)
AIMD Group
Bethanie J. H. Stadler
Magnetic Properties- Sputtered films
1.2
0.6
0.5
0.8
0.4
ll
0.3
0.4
0.1
memu
memu
0.2
^
0
-0.1
0
-0.4
-0.2
-0.3
-0.8
-0.4
-0.5
-0.6
-1000
-1.2
-500
0
Applied Field (Oe)


500
1000
-2000 -1500 -1000
-500
0
500
1000
1500
2000
Applied Field (Oe)
Dual-target sputtered and annealed YIG film on MgO. (a)
YIG grown on MgO without anneal with single target sputtering. (b)
AIMD Group
Bethanie J. H. Stadler
Measuring Faraday Rotation
Halfwave
Plate
Laser
Polarizing
Sample Beamsplitter
TM
TE
InGaAs
Detectors
Magnet
Lock-In
Amplifier
AIMD Group
Recorder
Bethanie J. H. Stadler
Faraday Rotation- MO films
1.8
Faraday Rotation (deg/  m)
1.6
YIG28
1.4
1.2
YIG51
1
0.8
%Ce
YIG29
0.6
MOCLD
sputtered
0.4
0.2
YIG36
YIG30
0
-0.2
0.6
0.8
1
1.2
1.4
1.6
Wavelength (mm)
AIMD Group
Bethanie J. H. Stadler