MagnetoOptic Materials for Integrated Photonics Bethanie J H

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/~stadl 002

Outline Motivation (isolators) n Garnet Layer n – – Fabrication Characterization Buffer Layers n Permanent Magnets n Photonic Crystals n AIMD Group Bethanie J. H. Stadler

Current Isolators Use YIG (Y 3 Fe 5 O 12) Polarizer Garnet Films n Laser Beam n n Magnet M AIMD Group Garnet Substrate Garnet Fabrication – LPE requires garnet substrates and high temperatures. Bulk permanent magnet q. F = 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 n Garnet Fabrication – – n n MOCVD MOCLD Dual-target sputtering Single-target sputtering Buffer and cladding layers (Mg. O, Si. O 2) Permanent magnet films (Sm. Co) AIMD Group Bethanie J. H. Stadler

Advantages n Fully integrating optical isolators on a single wafer Compact size n Low cost n Low magnetic field required n No focusing optics required n Now: Optical packaging (Laser diode + Isolator) n Later: Photonic integrated circuits (PICs) n AIMD Group Bethanie J. H. Stadler

Faraday Rotation Absorption Excitation Absorption l 1 l 0 - + n- n+ n Dispersion l Without Magnetic Field AIMD Group l 2 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 Film. Bethanie Devices, J. H. (2000). Stadler

Other materials Low Verdet constants: (longer lengths or stronger magnets) Magneto-optical glasses oxides and fluorides with Ce 3+, Pr 3+, Eu 2+, and Tb 3+ * 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 500 C ** High Faraday rotations due to octahedral Fe 2+ * 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

Outline Motivation (isolators) n Garnet Layer n – – Fabrication Characterization Buffer Layers n Permanent Magnets n Photonic Crystals n AIMD Group Bethanie J. H. Stadler

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 -5 Torr Oxygen Flow Rate 300 -700 sccm Nitrous Oxide Flow Rate 0 -500 sccm Argon Flow Rate 50 sccm Vaporizer Temperature 230 C Solution Flow Rate 5 ml/hr AIMD Group Growth line Liquid Pump N 2 O O 2 Y-, Fe-, Ce-(thd)* *(2, 2, 6, 6 -tetramethyl 1, 3, 5 -heptanedionate) Collaboration w/ Boston Applied Technologies Bethanie J. H. Stadler

Metalorganic Chemical Liquid Deposition (MOCLD) Motor& Gear Set 450 o. C Vertical Tube Furnace Dipping & Drying Chamber Solution Dispenser Precursors: Y(NO 3)3 and Fe(NO 3)3 in water/ethanol AIMD Group Collaboration w/ Boston Applied Technologies Bethanie J. H. Stadler

Specialized Fabrication Potential: Partial Pressure Differential H 2 O, RF Power, Ar Fe Y All gases conventionally fed in at same location Rotating substrate holder to LN 2 trap & pump AIMD Group O 2 Bethanie J. H. Stadler

Outline Motivation (isolators) n Garnet Layer n – – Fabrication Characterization Buffer Layers n Permanent Magnets n Photonic Crystals n AIMD Group Bethanie J. H. Stadler

Composition- MO techniques n n n Simply add dopant to precursor in MOCVD. Nonequilibrium techniques allows high dopant level. Y 1. 5 Bi 1. 5 Fe 3. 8 Al 1. 2 O 12 was grown by MOCLD. AIMD Group Bethanie J. H. Stadler

Effect of Composition on Structure Fe-poor: Y-O, YFe. O 3 Fe-rich: Fe-O, Y 2 Fe 4 O 9 Garnet: Y 3 Fe 5 O 12 AIMD Group Bethanie J. H. Stadler

Oxygen maintains single-phase YIG 1/2 (Y 2 O 3) A YFe. O 3 Y 2 Fe 4 O 9 B Fe Y 3 Fe 5 O 12 Fe 1 -y. O 1/2 (Fe 2 O 3) Fe 3 O 4 AIMD Group Bethanie J. H. Stadler

Sputtered/Annealed Film AIMD Group Bethanie J. H. Stadler

Structure of MOCLD on glass n MOCLD films were dense, polycrystalline films. AIMD Group Bethanie J. H. Stadler

Optical Properties- Dispersion AIMD Group Bethanie J. H. Stadler

Ce raises the index of YIG AIMD Group Bethanie J. H. Stadler

Magnetic Properties- Sputtered films n n Dual-target sputtered annealed YIG film on Mg. O. (a) YIG grown on Mg. O without anneal with single target sputtering. (b) AIMD Group Bethanie J. H. Stadler

Measuring Faraday Rotation Halfwave Plate Laser Polarizing Sample Beamsplitter TM TE Magnet Lock-In Amplifier AIMD Group In. Ga. As Detectors Recorder Bethanie J. H. Stadler

Faraday Rotation- MO films %Ce MOCLD sputtered AIMD Group Bethanie J. H. Stadler