Optical isolator is an optical component which allows light to transmit in only one direction. Optical isolator can be utilized to avoid to reflect light feedback into the optical device, and it has been widely used in optical communication and laser area. Optical isolator mainly use the Faraday Effect of the magneto-optic crystal. As an essential part of optical isolator, both sintered Samarium Cobalt magnets and sintered Neodymium magnets can be served as the optical isolator magnets.
What is Magneto-optical Effect?
Magneto-optical effect refers to the magnetic field effects to the interaction between matters and light. The electromagnetic wave will generate numerous phenomena when transmit through the medium which has been altered by the presence of the quasi static magnetic field. The conventional magneto-optical effect includes:
- Faraday Effect: can be applied to optical isolator and optical circulator.
- Kerr Effect: can be applied to the camera shutter.
- Zeeman Effect: can be applied to the measurement of specific charge-to-mass ratio and magnetic field of the celestial body.
What is Faraday Effect?
Faraday Effect refers to the interaction between the magnetic field and optical wave in the medium. The polarization of polarized light will be changed by the action of the magnetic field. Faraday Effect has been widely used in several measuring apparatus, including optical rotation, amplitude modulation, and remote sensing of the magnetic field.
The operating principle of the optical isolator base on the nonreciprocity of Faraday rotation. The main component of the optical isolator is the so-called Faraday rotator. Faraday rotator consists of Terbium Gallium Garnet (TGG) magneto-optical crystal and high performance permanent magnet. The magneto-optical crystal needs to apply the suitable magnetic field which requires permanent magnet provides enough magnetic field in the space of magneto-optical crystal. Micro Samarium Cobalt Magnets is the main choice in this application.