Cryogenic Faraday Isolator Based on TGG Ceramics

A cryogenic Faraday isolator based on terbium-gallium garnet (TGG) ceramics has been designed and studied in experiments. Its performance capabilities at the laser radiation power of 435 W are demonstrated, and our models suggest that the isolator should perform up to 2 kW. Thermal effects-thermally induced depolarization and thermal lens in the TGG ceramics in the 89-293 K temperature range are investigated. It is shown that the TGG ceramics compares well to the TGG monocrystal as a medium for Faraday isolators, including cryogenic ones. At the same time, in contrast to the TGG monocrystal, ceramics allows creating large-aperture Faraday isolators for lasers with high-average and high-peak power.