Faraday rotator
A Faraday rotator uses the Faraday effect to change the polarization of electromagnetic waves such as light or microwaves . It consists of an electric or permanent magnet and a suitable medium in which the Faraday effect occurs for the respective frequency range.
Faraday rotators can be used in conjunction with polarization-limiting components such as polarization filters , slits or the like. for switching, branching or for isolation, such as the optical isolators or isolators for microwaves . They are then also called Faraday isolators .
As a waveguide component for the direction-dependent transport of microwaves like a circulator , a Faraday rotator has a flange on one side and two ports at the other end, to which only the polarization directions of the wave that are at right angles to each other can enter or exit. In between there is a waveguide section in which a ferrite rod is located. A cylindrical coil is located around this section to generate and control the magnetic field. Circulators based on the Faraday principle can also be designed using stripline technology. With these, the Faraday rotator consists of a magnetized ferrite disc that rests on the stripline structure.
literature
- Helmut Naumann, G. Schröder, Martin Löffler-Mang: Manual components of optics: Fundamentals, materials, devices, measuring technology . 7th edition. Carl Hanser Verlag, 2014, ISBN 978-3-446-44115-6 .