LASER DEVICES AND ELEMENTS: Wide-aperture Faraday isolator for kilowatt average radiation powers

A Faraday isolator with an aperture of 20 mm and compensation of thermally induced polarisation and phase distortions of laser radiation is fabricated and tested experimentally. A considerable improvement in the isolation degree over a traditional Faraday isolator is demonstrated. For radiation power up to 750 W, the isolation degree lies in the range 24–26 dB and is limited only by the quality of TGG crystals.