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

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

3. 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
ICFM2001 Crimia October 1-5, 2001

4. 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
ICFM2001 Crimia October 1-5, 2001

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

6. 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）
ICFM2001 Crimia October 1-5, 2001

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

8. Faraday rotation of magnetic materials
(deg)
　figure of merit(deg/dB)
wavelength
(nm)
temperature
(K)
Mag. field
(T) Fe
3.825･105
578 RT
2.4 Co
1.88･105
546 〃 2 Ni
1.3･105
826
120 K
0.27
Y3Fe5O12
250
1150
100 K
Gd2BiFe5O12
1.01･104 44
800
MnSb
2.8･105
500
MnBi
5.0･105
1.43
633
YFeO3
4.9･103
NdFeO3
4.72･104
CrBr3
1.5K
EuO
5･105
104
660
4.2 K
2.08
CdCr2S4
3.8･103
35(80K)
1000 4K
0.6
ICFM2001 Crimia October 1-5, 2001

9. 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）
ICFM2001 Crimia October 1-5, 2001

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

11. MO Kerr rotation of magnetic materials
Photon energy
temperature
field
(deg)
(eV)
(K)
(T) Fe
0.87
0.75 RT Co
0.85
0.62 〃 Ni
0.19
3.1 Gd
0.16
4.3
Fe3O4
0.32 1
MnBi
0.7
1.9
PtMnSb
2.0
1.75
1.7
CoS2
1.1
0.8
4.2
0.4
CrBr3
3.5
2.9
EuO 6
2.1 12
USb0.8Te0.2
9.0 10
4.0
CoCr2S4
4.5 80
a-GdCo *
0.3
CeSb 90 2
ICFM2001 Crimia October 1-5, 2001
* "a-" means "amorphous".

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

13. Dielectric tensor Isotromic media；M//z
Invariant C4 for 90°rotation around z-axis
ICFM2001 Crimia October 1-5, 2001

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

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

16. 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
ICFM2001 Crimia October 1-5, 2001

17. 2.4 Electronic theory of Magneto-Optics
Magnetization→Splitting of spin-states
No direct cause of difference of optical response between LCP and RCP
Spin-orbit interaction→Splitting of orbital states
Absorption of circular polarization→Induction 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
ICFM2001 Crimia October 1-5, 2001

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

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

20. Orbital angular momentum-selection rules and circular dichroism
py-orbital
px-orbital
p+=px+ipy
Lz=+1
Lz=-1
p-=px-ipy
Lz=0
s-like
ICFM2001 Crimia October 1-5, 2001

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

22. MO lineshapes (1) 1.Diamagnetic lineshape Excited state Ground state0 1 2 
Without
magnetization
With
Lz=0
Lz=+1
Lz=-1
1+2
Photon energy
’xy
”xy
1.Diamagnetic lineshape
ICFM2001 Crimia October 1-5, 2001

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

24. 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.
ICFM2001 Crimia October 1-5, 2001

25. Measurement of magneto-optical spectra using retardation modulation techniquej
/4 P
PEM A D
quartz
Isotropic
medium B
fused silica
CaF2
Ge etc.
Piezoelectric
crystal
amplitude
position l
Retardation
=(2/)nl sin pt
=0sin pt
Light source
chopper
filter
ellipsoidal mirror
monochromator
polarizer
eletromagnet
sample
sample
analyzer
detector
computer
ICFM2001 Crimia October 1-5, 2001

26. 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
ICFM2001 Crimia October 1-5, 2001

27. Electronic level diagram of Fe3+ in magnetic garnets
6S (6A1, 6A1g)
6P (6T2, 6T1g)
without
perturbation
spin-orbit
interaction
tetrahedral
crystal field
(Td)
octahedral
(Oh)
J=7/2
J=5/2
J=3/2
5/2
-3/2 -
Jz=
3/2
7/2
5/2
-5/2
-3/2
-7/2 P+ P-
ICFM2001 Crimia October 1-5, 2001

28. Experimental and calculated magneto-optical spectra of Y3Fe5O12
calculation
Wavelength (nm)
Faraday rotation (arb. unit) -2 +2
Faraday rotation (deg/cm)
0.4
x104
0.8
-0.4
ICFM2001 Crimia October 1-5, 2001

29. Electronic states and optical transitions of Co2+ and Co3+ in Y3Fe5O12
(b)
ICFM2001 Crimia October 1-5, 2001

30. Theoretical and experimental magneto-optical spectra of Co-doped Y3Fe5O12
ICFM2001 Crimia October 1-5, 2001

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

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

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

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

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

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

37. MO spectra in R-Co Polar Kerr rotation (deg) Photon Energy (eV) -0.25 4 3 2
Photon Energy (eV)
-0.2
-0.4
-0.6
Polar Kerr rotation (deg)
Wavelength (nm)
300
400
500
600
700
ICFM2001 Crimia October 1-5, 2001

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

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

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

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

42. 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
ICFM2001 Crimia October 1-5, 2001

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

44. P-polarized or S-polarized light
Sample
試料回転
Sample stage
w (810nm)
Pole piece
P-polarized or S-polarized light
45°
Rotating
analyzer
w (810nm)
Filter
Analyzer
Optical arrangements
2w (405nm)
ICFM2001 Crimia October 1-5, 2001

45. Azimuthal dependence of
・　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
MSHG
linear
45
SHG intensity (counts/10sec.)
SHG intensity (counts/10sec.)
(a)　Linear (810nm)
(b)　SHG (405nm)
[Fe(3.75ML)/Au(3.75ML)] 超格子の　（Pin Pout）配置の線形および非線形の方位角依存性
ICFM2001 Crimia October 1-5, 2001

46. Calculated and experimental patterns :x=3.5
Dots：exp.
Solid curve：calc.
APP=1310, B=26, C=-88
(a) Pin-Pout
103
SHG intensity (counts/10sec.)
APS=-300, B=26, C=-88
(b) Pin-Sout
103
ASP=460, B=26, C=-88
(c) Sin-Pout
103
SHG intensity (counts/10sec.)
ASS=100, B=26, C=-88
(d) Sin-Sout
103
ICFM2001 Crimia October 1-5, 2001

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

48. Nonlinear Magneto-optical Microscope
Linear and nonlinear magneto-optical images of domains in CoNi film
50m
Schematic diagram L P F1
Objective lens
Sample F2 A
CCD
ICFM2001 Crimia October 1-5, 2001

49. 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
ICFM2001 Crimia October 1-5, 2001

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

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

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

53. MO-SNOM system using PEM
SNOM/AFM System
Controller
(SPI )
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
Bent fiber probe
ICFM2001 Crimia October 1-5, 2001

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

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

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

57. ＸMCD (X-ray magnetic circular dichroism)
2p1/2
2p3/2 3d
(12)
(6)
(2)
(1)
(3)
(14)
(a)
(b)
+1/2
-1/2
+3/2
-3/2 mj +2 +1 -1 -2 md
Occupation of minority 3d band
Simulated XMCD spectra corresponding to transitions (a) and (b) in the left diagram
(a)
(b)
ICFM2001 Crimia October 1-5, 2001

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

59. Domain image of MO media observed using XMCD of Fe L3-edge
SiN(70nm)/ TbFeCo(50nm)/SiN(20nm)/
Al(30nm)/SiN(20nm) MO 媒体
  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.
ICFM2001 Crimia October 1-5, 2001

60. Spin dynamics in nanoscale region
GaAs high speed optical switch
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.
ICFM2001 Crimia October 1-5, 2001

61. Further Prospects －For wider range of researches－
Time (t)：Ultra-short pulse→Spectroscopy 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
ICFM2001 Crimia October 1-5, 2001

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

63. Magneto-optical (MO) Recording
Recording:Thermomagnetic recording
Magnetic recording using laser irradiation
Reading out: Magneto-optical effect
Magnetically induced polarization state
MO disk, MD(Minidisk)
High rewritability：more than 107 times
Complex polarization optics
New magnetic concepts: MSR, MAMMOS
ICFM2001 Crimia October 1-5, 2001

64. 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
Commercial appearance of 5”MO disk (650MB)
Commercial appearance of 3.5 ”MO disk(128MB)
1991 Aratani(Sony) MSR
1992 Sony MD
1997 Sanyo ASMO(5” 6GB：L/G, MFM/MSR) standard
1998 Fujitsu GIGAMO(3.5” 1.3GB)
2000 Sanyo, Maxell iD-Photo(5cmφ730MB)
ICFM2001 Crimia October 1-5, 2001

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

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

67. MO recording How to record(2)
Use of compensation point
writing
Amorphous TbFeCo:
Ferrimagnet with Tcomp
HC takes maximum at Tcomp
Stability of small recorded marks Hc M Tb
FeCo
Mtotal
Fe,Co Tb
Tcomp Tc T RT
ICFM2001 Crimia October 1-5, 2001

68. アモルファスTbFeCo薄膜 TM
(Fe,Co) R
(Tb)
ICFM2001 Crimia October 1-5, 2001

69. 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
Constant field
Modulated field
Magnetic head
(a) LIM
(b) MFM
ICFM2001 Crimia October 1-5, 2001

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

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

72. Structure of MO Head ICFM2001 Crimia October 1-5, 2001 Bias field coil
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
ICFM2001 Crimia October 1-5, 2001

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

74. MSR (Magnetically induced super-resolution)
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 α d
ICFM2001 Crimia October 1-5, 2001

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

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

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

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

79. Super-RENS super-resolution near-field system
AgOx film：decomposition and precipitation of Ag
Scattering center→near field
Ag plasmon→enhancement
reversible
Applicable to both phase-change and MO recording
高温スポット
近接場散乱
ICFM2001 Crimia October 1-5, 2001

80. 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] 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.
ICFM2001 Crimia October 1-5, 2001

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

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

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

84. Hybrid Recording 405nm LD Recording head (SIL) Readout MR head
Achieved 60Gbit/in2
H. Saga et al. Digest
MORIS/APDSC2000, TuE-05, p.92.
TbFeCo
disk
ICFM2001 Crimia October 1-5, 2001

85. 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
ICFM2001 Crimia October 1-5, 2001

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

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

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

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

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

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

92. Polarization independent isolator
Fiber 2
Fiber 1
Forward direction
Reverse direction
½ waveplate C
Birefringent plate B2 B2 B1 F C
Birefringent plate B1 ×
Faraday rotator F
ICFM2001 Crimia October 1-5, 2001

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

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

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

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

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

98. 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
ICFM2001 Crimia October 1-5, 2001

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

100. 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.
ICFM2001 Crimia October 1-5, 2001