TSAG-based cryogenic Faraday isolator

Abstract

Thermooptical and magnetooptical properties of novel magnetoactive crystal terbium–scandium aluminum garnet were investigated at temperature range 80–300K. It is shown that Verdet constant increases inversely proportional to temperature, and thermally induced depolarization, and the optical power of the thermal lens is reduced significantly with cooling from 290K to 80K. According to estimates, TSAG crystals in [111] orientation allow to create a cryogenic Faraday isolator provides a degree of isolation of 30dB with the laser power exceeds ∼6kW, it is estimated that the transition to the [001] orientation allows to provide degree of isolation of 30dB at a laser power higher than 400kW.