Optical isolator is an optical component which enables light to transmit in only one direction. Optical isolator can be served to prevent reflecting light feedback into the optical device and then widely utilized by optical communication and laser area. Optical isolator mainly exploited the Faraday Effect of the magneto-optic crystal. Either sintered Neodymium magnet or sintered Samarium Cobalt magnet be used as the optical isolator magnet.

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 different phenomena when transmit along the medium which has been altered by the presence of the quasi static magnetic field. The conventional magneto-optical effect and relevant applications 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 optical wave in the medium and magnetic field. The polarization of polarized light will be changed by the action of the magnetic field. Faraday Effect has been widely used in measuring apparatus, such as optical rotation, amplitude modulation, and remote sensing of the magnetic field.

About Optical Isolator Magnet

The operating principle of the optical isolator base on the nonreciprocity of Faraday rotation. The main part 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. Optical isolator magnet should provide sufficient magnetic field strength in the space of magneto-optical crystal. SmCo micro magnet is the main choice in this application.