Integrated Magneto-Optical Isolator for Feasible Photonic Integrated ...

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

θF = V B l V-material constant B- magnetic field l- pathlength


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


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


Faraday Rotation Absorption

Excitation

Absorption

λ1 λ0

λ0

-

+

n-

n+ n

Dispersion

λ Without Magnetic Field AIMD Group

λ2

n λs λ With Applied Magnetic Field Bethanie J. H. Stadler

Garnet can accommodate half the periodic table! dodecahedral site octahedral site tetrahedral site oxygen

ΘF (T,λ) = C(λ) Mc(T) + A(λ) Ma(T) + D(λ) 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 J. H.(2003). Stadler **T. Teper,Group F. Illievski, C. Ross, R Zaman, R Ram, S Sung, B. Stadler, J. Appl.Bethanie Phys. 93


– –



AIMD Group


Metalorganic Chemical Vapor Deposition (MOCVD) Heater

To Pump By pass line

Substrates Vaporizer Ar 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

Growth line Liquid Pump N2O O2

Y-, Fe-, Ce-(thd)*

*(2,2,6,6-tetramethyl1,3,5-heptanedionate)

Collaboration w/ Boston Applied Technologies


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


Specialized Fabrication Potential: Partial Pressure Differential H2O, RF Power,

Ar

Fe

Y

All gases conventionally fed in at same location

Rotating substrate holder

to LN2 trap & pump

AIMD Group

O2



– –



AIMD Group


Composition- MO techniques Table II: Sample Information Sample Name YIG28 (111) YIG29 YIG 30 YIG36 YIG51

Thickness (µm) 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


Intensity (arb. units) 20

10

20 25 Q

Q

30

30

35

2 Theta AIMD Group

40

0 45 50 20

+

25 30

+

431

420 (100) 35

MgO Substrate

MgO Substrate

422 (44)

+

40 45 50

2 Theta

Garnet: Y3Fe5O12 1000

800

400

200

20 25

MgO Substrate

+

332

30

30

MgO Substrate

Fe-poor: Y-O, YFeO3 20

440 (30)

40

101 (100)

10

220

Intensity (arb. units) 50

Intensity (arb. units)

MgO Substrate

202 (21) 040 (20) 212 (13)

031 (5)

MgO Substrate

002 (28) 210 (12)

40 121 (100)

50

200 (20)

111 (50)

Effect of Composition on Structure

+

+

0

Fe-rich: Fe-O, Y2Fe4O9

600

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


Sputtered/Annealed Film Y3Fe5O12

1800 1600

25

30

35

40

532

332

200 0

440

400

521

800 600

431

400

1200 1000

422

1400

321

Intensity [Counts]

420

2000

45

50

2-Theta

AIMD Group


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


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


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


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


Measuring Faraday Rotation Halfwave Plate Laser

Polarizing Sample Beamsplitter TM TE Magnet

Lock-In Amplifier

AIMD Group

InGaAs Detectors

Recorder


Faraday Rotation- MO films 1.8

Faraday Rotation (deg/ µ 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
