File:Faraday isolator.svg

English: Faraday isolator allows the transmission of light in only one direction. It is made of three parts, an input polarizer, a Faraday rotator and an analyzer. The value of magnetic field (B) and length (d) for a give material of Verdet constant (${\displaystyle \nu }$), is chosen in such a way that when the light passes through it along the direction of magnetic field, it will get 45° clockwise turn in polarization.The light going in the forward direction passes through input polarizer and gets 0° polarized and then it passes through Faraday rotator along the direction of magnetic field (B) and gets turned 45° clockwise along the direction of propagation because of Faraday effect and then it passes through analyzer (45° polarizer), thus light passes through in the forward direction. The light going in the backward direction passes through analyzer (45° polarizer) and gets 45° polarized and then it passes through Faraday rotator opposite to the direction of magnetic field (B) and gets turned 45° anticlockwise along the direction of propagation thus light gets 90° polarized which is blocked by input polarizer (0° polarizer), thus light does not comes through in the backward direction.