The sections in this article are

• 1 Optical Isolators
• 2 Magneto-Optic Effect
• 3 Faraday Rotating Materials
• 4 Paramagnetics
• 5 Diamagnetics
• 6 Ferromagnetics
• 7 Magnets
• 8 Polarizers
• 9 Miniaturized Isolators For Diode Lasers and Fiber Optics
• 10 Isolator Characteristics
• 11 Polarization Effects
• 12 Significance of Wavelength
• 13 Isolation Limitations
• 14 Future Isolators
• 15 Optical Circulators
• 16 Acknowledgments