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ICFM2001 Crimia October 1-5, 2001 Recent Advances in Magneto-Optics Katsuaki Sato Department of Applied Physics Tokyo University of Agriculture & Technology.

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Presentation on theme: "ICFM2001 Crimia October 1-5, 2001 Recent Advances in Magneto-Optics Katsuaki Sato Department of Applied Physics Tokyo University of Agriculture & Technology."— Presentation transcript:

1 ICFM2001 Crimia October 1-5, 2001 Recent Advances in Magneto-Optics Katsuaki Sato Department of Applied Physics Tokyo University of Agriculture & Technology

2 ICFM2001 Crimia October 1-5, 2001 CONTENTS 1.Introduction 2.Fundamentals of Magneto-Optics 3.Magneto-Optical Spectra Experiments and theory 4.Recent Advances in Magneto-Optics Magneto-optics in nano-structures Nonlinear magneto-optical effect Scanning near-field magneto-optical microscope 5.Current Status in Magneto-Optical Devices Magneto-optical disk storages Magneto-optical isolators for optical communication Other applications 6.Summary

3 ICFM2001 Crimia October 1-5, 2001 1. Introduction Magneto-Optical Effect Discovered by Faraday on 1845 Phenomenon Change of Linear Polarization to Elliptically Polarized Light Accompanied by Rotation of Principal Axis Cause Difference of Optical Response between LCP and RCP Application –Magneto-Optical Disk –Optical Isolator –Current Sensors –Observation Technique

4 ICFM2001 Crimia October 1-5, 2001 2.Fundamentals of Magneto-Optics MO Effect in Wide Meaning Any change of optical response induced by magnetization MO Effect in Narrow Meaning Change of intensity or polarization induced by magentization –Faraday effect –MOKE(Magneto-optical Kerr effect) –Cotton-Mouton effect

5 ICFM2001 Crimia October 1-5, 2001 2.1 Faraday Effect (a) Faraday Configuration: –Magnetization // Light Vector (b)Voigt Configuration: –Magnetization Light Vector

6 ICFM2001 Crimia October 1-5, 2001 Faraday Effect MO effect for optical transmission –Magnetic rotation Faraday rotation F –Magnetic Circular Dichroism Faraday Ellipticity F Comparison to Natural Optical Rotation –Faraday Effect is Nonreciprocal (Double rotation for round trip) –Natural rotation is Reciprocal (Zero for round trip) Verdet Constant – F =VlH (For paramagnetic and diamagnetic materials

7 ICFM2001 Crimia October 1-5, 2001 Illustration of Faraday Effect For linearly polarized light incidence, Elliptically polarized light goes out (MCD) With the principal axis rotated (Magnetic rotation) Linearly polarized light Elliptically Polarized light Rotation of Principal axis

8 ICFM2001 Crimia October 1-5, 2001 Faraday rotation of magnetic materials Materialsrotation (deg) figure of merit(deg/dB) wavelength (nm) temperature (K) Mag. field (T) Fe 3.825 10 5 578RT2.4 Co 1.88 10 5 546 2 Ni 1.3 10 5 826120 K0.27 Y 3 Fe 5 O 12 250 1150100 K Gd 2 BiFe 5 O 12 1.01 10 4 44800RT MnSb 2.8 10 5 500 MnBi 5.0 10 5 1.43633 YFeO 3 4.9 10 3 633 NdFeO 3 4.72 10 4 633 CrBr 3 1.3 10 5 5001.5K EuO 5 10 5 10 4 6604.2 K2.08 CdCr 2 S 4 3.8 10 3 35(80K)10004K0.6

9 ICFM2001 Crimia October 1-5, 2001 2.2 Magneto-Optical Kerr Effect Three kinds of MO Kerr effects –Polar Kerr Magnetization is oriented perpendicular to the suraface –Longitudinal Kerr Magnetization is in plane and is parallel to the plane of incidence –Transverse Kerr Magnetization is in plane and is perpendicular to the plane of incidence

10 ICFM2001 Crimia October 1-5, 2001 Magneto-optical Kerr effect Polar Longitudinal Transverse M MM

11 ICFM2001 Crimia October 1-5, 2001 MO Kerr rotation of magnetic materials Materialsrotation Photon energy temperature field (deg)(eV)(K)(T) Fe0.870.75RT Co0.850.62 Ni0.193.1 Gd0.164.3 Fe 3 O 4 0.321 MnBi0.71.9 PtMnSb2.01.75 1.7 CoS 2 1.10.84.20.4 CrBr 3 3.52.94.2 EuO62.112 USb 0.8 Te 0.2 9.00.8104.0 CoCr 2 S 4 4.50.780 a-GdCo * 0.31.9RT CeSb90 2 * "a-" means "amorphous".

12 ICFM2001 Crimia October 1-5, 2001 2.3 Electromagnetism and Magnetooptics Light is the electromagnetic wave. Transmission of EM wave Maxwell equation Medium is regareded as continuumdielectric permeability tensor –Effect of Magnetic fieldmainly to off-diagonal element Eigenequation Complex refractive index two eigenvalues eigenfunctions right and left circularpolarization –Phase difference between RCP and LCProtation –Amplitude difference circular dichroism

13 ICFM2001 Crimia October 1-5, 2001 Dielectric tensor Isotromic media M//z Invariant C 4 for 90°rotation around z-axis

14 ICFM2001 Crimia October 1-5, 2001 MO Equations (1) Eigenvalue Eigenfunction LCP and RCP Without off-diagonal terms No difference between LCP & RCP No magnetooptical effect Maxwell Equation Eigenequation

15 ICFM2001 Crimia October 1-5, 2001 MO Equations (2) Both diagonal and off-diagonal terms contribute to Magneto-optical effect

16 ICFM2001 Crimia October 1-5, 2001 Phenomenology of MO effect Linearly polarized light can be decomposed to LCP and RCP Difference in phase causes rotation of the direction of Linear polarization Difference in amplitudes makes Elliptically polarized light In general, elliptically polarized light With the principal axis rotated

17 ICFM2001 Crimia October 1-5, 2001 2.4 Electronic theory of Magneto- Optics MagnetizationSplitting of spin-states –No direct cause of difference of optical response between LCP and RCP Spin-orbit interactionSplitting of orbital states –Absorption of circular polarizationInduction of circular motion of electrons Condition for large magneto-optical response –Presence of strong (allowed) transitions –Involving elements with large spin-orbit interaction –Not directly related with Magnetization

18 ICFM2001 Crimia October 1-5, 2001 Dielectric functions derived from Kubo formula where

19 ICFM2001 Crimia October 1-5, 2001 Microscopic concepts of electronic polarization = + + + + + + - - Unperturbed wavefunction Wavefunction perturbed by electric field E S-likeP-like Expansion by unperturbed orbitals

20 ICFM2001 Crimia October 1-5, 2001 Orbital angular momentum-selection rules and circular dichroism L z =0 L z =+1 L z =-1 s-like p - =p x -ip y p + =p x +ip y p x -orbital p y -orbital

21 ICFM2001 Crimia October 1-5, 2001 Role of Spin-Orbit Interaction L=1 L=0 L Z =+1,0,-1 L Z =0 Jz=-3/2 Jz=-1/2 Jz=+1/2 Jz=+3/2 Jz=-1/2 Jz=+1/2 Exchange splitting Exchange +spin-orbit Without magnetization

22 ICFM2001 Crimia October 1-5, 2001 MO lineshapes (1) Excited state Ground state 0 1 2 Without magnetization With magnetization L z =0 L z =+1 L z =-1 1+2 Photon energy xy 1.Diamagnetic lineshape

23 ICFM2001 Crimia October 1-5, 2001 MO lineshapes (2) excited state ground state f+f+ f-f- f=f + - f - 0 without magnetic field with magnetic field xy photon energy (a) (b) dielectric constant 2.Paramagnetic lineshape

24 ICFM2001 Crimia October 1-5, 2001 3. Magneto-Optical Spectra Measurement technique Magnetic garnets Metallic ferromagnet Fe, Co, Ni Intermetallic compounds and alloys PtMnSb etc. Magnetic semiconductor CdMnTe etc. Superlattices Pt/Co, Fe/Au etc. Amorphous TbFeCo, GdFeCo etc.

25 ICFM2001 Crimia October 1-5, 2001 Measurement of magneto-optical spectra using retardation modulation technique i j /4 P PEM A D quartz Isotropic medium B fused silica CaF 2 Ge etc. Piezoelectric crystal amplitude position l Retardation =( 2 / ) nl sin pt = 0 sin pt sample eletromagnet polarizer analyzer detector sample computer monochro mator ellipsoidal mirror chopper filter Light source

26 ICFM2001 Crimia October 1-5, 2001 Magnetic garnets One of the most intensively investigated magneto-optical materials Three different cation sites; octahedral, tetrahedral and dodecahedral sites Ferrimagnetic Large magneto-optical effect due to strong charge-transfer transition Enhancement of magneto-optical effect by Bi- substitution at the dodecahedral site

27 ICFM2001 Crimia October 1-5, 2001 Electronic level diagram of Fe 3+ in magnetic garnets

28 ICFM2001 Crimia October 1-5, 2001 experiment calculation 300 400 500 600 Wavelength (nm) Faraday rotation (arb. unit) 0 -2 0 +2 Faraday rotation (deg/cm) 0.4 x 10 4 0.8 -0.4 Experimental and calculated magneto-optical spectra of Y 3 Fe 5 O 12

29 ICFM2001 Crimia October 1-5, 2001 Electronic states and optical transitions of Co 2+ and Co 3+ in Y 3 Fe 5 O 12 (a) (b)

30 ICFM2001 Crimia October 1-5, 2001 Theoretical and experimental magneto- optical spectra of Co-doped Y 3 Fe 5 O 12

31 ICFM2001 Crimia October 1-5, 2001 Theoretical and experimental MO spectra of bcc Fe Katayama theory Krinchik

32 ICFM2001 Crimia October 1-5, 2001 (a) (b)(c) MO spectra of PtMnSb Magneto-optical Kerr rotation θ K and ellipticity η K Diagonal dielectric functions Off-diagonal Dielectric function

33 ICFM2001 Crimia October 1-5, 2001 Comparison of theoretical and experimental spectra of half-metallic PtMnSb (a) (b) (d) (c) After Oppeneer

34 ICFM2001 Crimia October 1-5, 2001 Magneto-optical spectra of CdMnTe Photon Energy (eV) Faraday rotation spectra (deg)

35 ICFM2001 Crimia October 1-5, 2001 Pt/Co superlattices Photon energy (eV) simulation experiment Kerr rotation and ellipticity(min) rotation elliptoicity PtCo alloy Pt(10)/Co(5) Pt(18)/Co(5) Pt(40)/Co(20)

36 ICFM2001 Crimia October 1-5, 2001 Wavelength (nm) Polar Kerr rotation (min) MO spectra in RE-TM (1)

37 ICFM2001 Crimia October 1-5, 2001 54 32 Photon Energy (eV) 0 -0.2 -0.4 -0.6 Polar Kerr rotation (deg) Wavelength (nm) 300400500600 700 MO spectra in R-Co

38 ICFM2001 Crimia October 1-5, 2001 MO spectra of Fe/Au superlattice

39 ICFM2001 Crimia October 1-5, 2001 Calculated MO spectra of Fe/Au superlattice By M.Yamaguchi et al.

40 ICFM2001 Crimia October 1-5, 2001 Au/Fe/Au sandwich structure By Y.Suzuki et al.

41 ICFM2001 Crimia October 1-5, 2001 4. Recent Advances in Magneto-Optics Nonlinear magneto-optics Scanning near-field magneto-optical microscope (MO-SNOM) X-ray magneto-optical Imaging

42 ICFM2001 Crimia October 1-5, 2001 NOMOKE Nonlinear magneto-optical Kerr effect Why SHG is sensitive to surfaces? Large nonlinear magneto-optical effect Experimental results on Fe/Au superlattice Theoretical analysis Future perspective

43 ICFM2001 Crimia October 1-5, 2001 LD pump SHG laser lens Mirror Chopper Lens Analyzer Filter PMT Ti: sapphire laser Mirror Filter polarizer Berek compensator Sample Stage controller Electromagnet Photon counterComputer =532nm =810nm Pulse=150fs P=600mW rep80MHz Photon counting MSHG Measurement System

44 ICFM2001 Crimia October 1-5, 2001 P-polarized or S-polarized light nm) Analyzer Filter nm) Pole piece Rotating analyzer Sample stage 45° Sample Optical arrangements

45 ICFM2001 Crimia October 1-5, 2001 [Fe(3.75ML)/Au(3.75ML)] P in P out (a) Linear (810nm)(b) SHG (405nm) Linear optical response ( =810nm) The isotropic response for the azimuthal angle Nonlinear optical response ( =405nm) The 4-fold symmetry pattern Azimuthal pattern show 45 -rotation by reversing the magnetic field SHG intensity (counts/10sec.) 45 linear MSHG Azimuthal dependence of

46 ICFM2001 Crimia October 1-5, 2001 A SP =460, B=26, C=- 88 (c) Sin-Pout 10 3 SHG intensity (counts/10sec.) A SS =100, B=26, C=- 88 (d) Sin-Sout 10 3 A PP =1310, B=26, C=-88 (a) Pin-Pout 10 3 SHG intensity (counts/10sec.) A PS =-300, B=26, C=-88 (b) Pin-Sout 10 3 Dots exp. Solid curve calc. Calculated and experimental patterns :x=3.5

47 ICFM2001 Crimia October 1-5, 2001 Fe(1.75ML)/Au(1.75ML) Sin The curves show a shift for two opposite directions of magnetic field S-polarized light ω(810nm) 2 (405nm) Analyzer 45° Electromagnet Rotating Analyzer Filter Nonlinear Kerr Effect = 31.1°

48 ICFM2001 Crimia October 1-5, 2001 Nonlinear Magneto-optical Microscope Schematic diagram L P F1F1 Objective lens Sample F2F2 A CCD Linear and nonlinear magneto-optical images of domains in CoNi film 50 m

49 ICFM2001 Crimia October 1-5, 2001 MO-SNOM (Scanning near-field magneto-optical microscope) Near-field optics Optical fiber probe Optical retardation modulation technique Stokes parameter of fiber probe Observation of recorded bits on MO disk

50 ICFM2001 Crimia October 1-5, 2001 Near-field Critical angle c Medium 2 Medium 1 i c Evanescent wave Total reflection and near field d Propagating wave Evanescent field Scattered wave Scattered wave by a small sphere placed in the evanescent field produced by another sphere

51 ICFM2001 Crimia October 1-5, 2001 Levitation control methods Sample surface Fiber probe Quartz oscillator Piezoelectrically- driven xyz-stage Piezoelectrically- driven xyz-stage bimorph LD Photo diode Shear force typeCanti-lever type

52 ICFM2001 Crimia October 1-5, 2001 Collection mode(a) and illumination mode(b)

53 ICFM2001 Crimia October 1-5, 2001 SNOM/AFM System Bent fiber probe Controller ( SPI3800 3800 ) PEM Ar ion laser Signal generator Lock-in Amplifier Computer XYZ scanner Bimorph Filter Sample Photodiode Photomultiplier Optical fiber probe Analyzer Polarizer Compensator LD MO-SNOM system using PEM

54 ICFM2001 Crimia October 1-5, 2001 topography MO image Recorded marks on MO disk observed by MO-SNOM

55 ICFM2001 Crimia October 1-5, 2001 MO-SNOM image of 0.2 m recorded marks on Pt/Co MO disk MO image Resolution Line profileTopographic image

56 ICFM2001 Crimia October 1-5, 2001 Reflection type SNOM P. Fumagalli, A. Rosenberger, G. Eggers, A. Münnemann, N. Held, G. Güntherodt: Appl. Phys. Lett. 72, 2803 (1998)

57 ICFM2001 Crimia October 1-5, 2001 2p 1/2 2p 3/2 3d (12) (6) (2) (1) (3) (6) (3) (14) (a) (b) +1/2-1/2 +3/2+1/2-1/2-3/2 mjmj mjmj +2+10-2 mdmd Occupation of minority 3d band MCD (X-ray magnetic circular dichroism) Simulated XMCD spectra corresponding to transitions (a) and (b) in the left diagram (a) (b)

58 ICFM2001 Crimia October 1-5, 2001 (b) Magnetic circular dichroism of L-edge

59 ICFM2001 Crimia October 1-5, 2001 Domain image of MO media observed using XMCD of Fe L 3 -edge SiN(70nm)/ TbFeCo(50nm)/SiN(20nm)/ Al(30nm)/SiN(20nm) MO N. Takagi, H. Ishida, A. Yamaguchi, H. Noguchi, M. Kume, S. Tsunashima, M. Kumazawa, and P. Fischer: Digest Joint MORIS/APDSC2000, Nagoya, October 30-November 2, 2000, WeG-05, p.114.

60 ICFM2001 Crimia October 1-5, 2001 Spin dynamics in nanoscale region Th. Gerrits, H. van den Berg, O. Gielkens, K.J. Veenstra and Th. Rasing: Digest Joint MORIS/APDSC2000, Nagoya, October 30- November 2, 2000, TuC-05, p.24. GaAs high speed optical switch

61 ICFM2001 Crimia October 1-5, 2001 Further Prospects For wider range of researches Time (t) Ultra-short pulseSpectroscopy using ps, fs- lasers, Pump-probe technique Frequency ( ) Broad band width, Synchrotron radiation Wavevector (k) Diffraction, scattering, magneto-optical diffraction Length (x) Observation of nanoscale magetism, Appertureless SNOM, Spin-polarized STM, Xray microscope Phase ( ) Sagnac interferrometer

62 ICFM2001 Crimia October 1-5, 2001 5. Magneto-optical Application Magneto-optical disk for high density storage Optical isolators for optical communication Other applications

63 ICFM2001 Crimia October 1-5, 2001 Magneto-optical (MO) Recording Recording:Thermomagnetic recordingRecording:Thermomagnetic recording –Magnetic recording using laser irradiation Reading out: Magneto-optical effectReading out: Magneto-optical effect –Magnetically induced polarization state MO disk, MD(Minidisk) High rewritability more than 10 7 times Complex polarization optics New magnetic concepts: MSR, MAMMOS

64 ICFM2001 Crimia October 1-5, 2001 History of MO recording 1962 Conger,Tomlinson Proposal for MO memory 1967 Mee Fan Proposal of beam-addressable MO recording 1971 Argard (Honeywel)MO disk using MnBi films 1972 Suits(IBM)MO disk using EuO films 1973 Chaudhari(IBM)Compensation point recording to a-GdCo film 1976 Sakurai(Osaka U)Curie point recording on a-TbFe films1980 Imamura(KDD)Code-file MO memory using a-TbFe films 1981 Togami(NHK)TV picture recording using a-GdCo MO disk 1988 Commercial appearance of 5MO disk (650MB) 1889 Commercial appearance of 3.5 MO disk(128MB) 1991 Aratani(Sony)MSR 1992 SonyMD 1997 SanyoASMO(5 6GB L/G, MFM/MSR) standard 1998 FujitsuGIGAMO(3.5 1.3GB) 2000 Sanyo, Maxell iD-Photo(5cmφ730MB)

65 ICFM2001 Crimia October 1-5, 2001 Structure of MO disk media MO disk structure Polycarbonate substrate SiNx layer for protection and MO-enhancement MO-recording layer (amorphous TbFeCo) Al reflection layer LandGroove Resin

66 ICFM2001 Crimia October 1-5, 2001 Temperature increase by focused laser beam Magnetization is reduced when T exceeds Tc Record bits by external field when cooling MO recording How to record(1) External field MO media Temp Laser spot TcTc Coil M Tc

67 ICFM2001 Crimia October 1-5, 2001 Use of compensation point writing Amorphous TbFeCo: Ferrimagnet with Tcomp H C takes maximum at T comp –Stability of small recorded marks MO recording How to record(2) T M Tb FeCo T comp HcHc M total RT TcTc Tb Fe,Co

68 ICFM2001 Crimia October 1-5, 2001 TbFeCo TM (Fe,Co) TM (Fe,Co) R (Tb) R (Tb)

69 ICFM2001 Crimia October 1-5, 2001 Two recording modes Light intensity modulation (LIM) present MO –Laser light is modulated by electrical signal –Constant magnetic field –Elliptical marks Magnetic field modulation (MFM) MD, ASMO –Field modulation by electrical signal –Constant laser intensity –Crescent-shaped marks Modulated laser beam Constant laser beam Constant field Modulated field Magnetic head (a) LIM (b) MFM

70 ICFM2001 Crimia October 1-5, 2001 Shape of Recorded Marks (a) LIM (b) MFM

71 ICFM2001 Crimia October 1-5, 2001 MO recording How to read Magneto-optical conversion of magnetic signal to electric signal D1 D2 +-+- LD Polarized Beam Splitter S N N S N S Differential detection

72 ICFM2001 Crimia October 1-5, 2001 Structure of MO Head Laser diode Photo-detector Focusing lens Half wave-plate lens Beam splitter PBS (polarizing beam splitter) Rotation of polarization Recorded marks Track pitch Bias field coil MO film mirror

73 ICFM2001 Crimia October 1-5, 2001 Advances in MO recording 1.Super resolution 1.MSR 2.MAMMOS/DWDD 2.Use of Blue Lasers 3.Near field 1.SIL 2.Super-RENS (AgO x )

74 ICFM2001 Crimia October 1-5, 2001 Resolution is determined by diffraction limit – d=0.6λ/NA, where NA=n sin α –Marks smaller than wavelength cannot be resolved Separation of recording and reading layers Light intensity distribution is utilized –Magnetization is transferred only at the heated region MSR (Magnetically induced super-resolution) α d

75 ICFM2001 Crimia October 1-5, 2001 Illustration of 3 kinds of MSR

76 ICFM2001 Crimia October 1-5, 2001 AS-MO standard

77 ICFM2001 Crimia October 1-5, 2001 iD-Photo specification

78 ICFM2001 Crimia October 1-5, 2001 MAMMOS (magnetic amplification MO system)

79 ICFM2001 Crimia October 1-5, 2001 Super-RENS super-resolution near-field system AgOx film decomposition and precipitation of Ag –Scattering centernear field –Ag plasmonenhancement –reversible Applicable to both phase- change and MO recording

80 ICFM2001 Crimia October 1-5, 2001 To shorter wavelengths DVD-ROM : Using 405nm laser, successful play back of marks was attained with track pitch =0.26 m mark length =213 m (capacity 25GB) using NA=0.85 lens [i] [i] [i] M. Katsumura, et al.: Digest ISOM2000, Sept. 5-9, 2000, Chitose, p. 18. DVD-RW : Using 405nm laser, read / write of recorded marks of track pitch=0.34 m and mark length=0.29 m in 35 m two-layered disk(capacity:27GB) was succeeded using NA=0.65 lens, achieving 33Mbps transfer rate [ii] [ii] T. Akiyama, M. Uno, H. Kitaura, K. Narumi, K. Nishiuchi and N. Yamada: Digest ISOM2000, Sept. 5-9, 2000, Chitose, p. 116. [ii]

81 ICFM2001 Crimia October 1-5, 2001 Read/Write using Blue-violet LD and SIL (solid immersion lens) 405nm LD head NA=1.5 405nm 80nm mark 40GB I. Ichimura et. al. (Sony), ISOM2000 FrM01

82 ICFM2001 Crimia October 1-5, 2001 SIL (solid immersion lens)

83 ICFM2001 Crimia October 1-5, 2001 Optical recording using SIL

84 ICFM2001 Crimia October 1-5, 2001 Hybrid Recording H. Saga et al. Digest MORIS/APDSC2000, TuE-05, p.92. 405nm LD TbFeCo disk Readout MR head Recording head (SIL) Achieved 60Gbit/in 2

85 ICFM2001 Crimia October 1-5, 2001 Optical elements for fiber communication Necessity of optical isolators Principles of optical isolators Structure of optical isolators –Polarization-independent type –Polarization-dependent type Optical multiplexing and needs of optical isolators

86 ICFM2001 Crimia October 1-5, 2001 Optical circuit elements proposed by Dillon (a) Rotator (b) Isolator (c) Circulator (d) Modulator (e) Latching switch

87 ICFM2001 Crimia October 1-5, 2001 Optical isolator for Laser diode module Optical isolator for LD module Optical fiber Signal source Laser diode module

88 ICFM2001 Crimia October 1-5, 2001 Optical fiber amplifier and optical isolator EDFA isolators mixer Pumping laser Band pass filter output input

89 ICFM2001 Crimia October 1-5, 2001 Optical Circulator A B C D

90 ICFM2001 Crimia October 1-5, 2001 Optical add-drop and circulator circulator Fiber grating circulator

91 ICFM2001 Crimia October 1-5, 2001 Polarization dependent isolator polarizer analyzer mag.field Faraday rotator input reflected beam

92 ICFM2001 Crimia October 1-5, 2001 Polarization independent isolator Fiber 2 Fiber 1 Forward direction Reverse direction ½ waveplate C Birefringent plate B 2 B2B2 B1B1 F C Birefringent plate B 1 Fiber 2 × Faraday rotator F × Fiber 1

93 ICFM2001 Crimia October 1-5, 2001 Magneto-optical circulator Prism polarizer A Faraday rotator Prism polarizer B Half wave plate Port 1 Port 3 Port 2 Port 4 Reflection prism

94 ICFM2001 Crimia October 1-5, 2001 Optical absorption in YIG

95 ICFM2001 Crimia October 1-5, 2001 Waveguide type isolators

96 ICFM2001 Crimia October 1-5, 2001 Mach-Zehnder type isolator

97 ICFM2001 Crimia October 1-5, 2001 Current-field sensor

98 ICFM2001 Crimia October 1-5, 2001 Current sensors used by power engineers Before installation After installation Magnetic core Hook Magneto-optical sensor head Fastening screw Optical fiber Fail-safe string Aerial wire

99 ICFM2001 Crimia October 1-5, 2001 Field sensor using optical fibers

100 ICFM2001 Crimia October 1-5, 2001 SUMMARY Basic concepts of magneto-optics are described. Macroscopic and microscopic origins of magneto-optics are described. Some of the recent development of magneto-optics are also given. Some of the recent application are summarized.


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