Large-aperture Faraday isolator based on a terbium gallium garnet crystal

Abstract

Unique Faraday isolator based on a TGG single crystal with aperture diameter of 40 mm for high average power lasers has been fabricated and investigated experimentally. The device provides a stable isolation ratio over 30 dB for large-radius laser beams with kilowatt average power radiation typical for high-power applications.

Thermo-optical and magneto-optical characteristics of CeF 3 crystal

“…The same plot shows for comparison the results of measurements of thermal lens in the TGG crystal having length L TGG ¼ 9.5 mm for the same value of laser beam radius (circles). Taking into account that TGG sample length was 27% larger, from the experimental data and formula (12) we can conclude that the parameter (aP/k) in the CeF 3 crystal is 6.5 times less than in the TGG crystal. Thereby, the thermal lens induced in CeF 3 has a 6.5 lower optical strength for the same laser beam parameters.…”

“…According to (12), from the F À1 (P 0 ) dependence we can find the magnitude of aP/k as a fitting parameter: (aP/k) CeF3 ¼ 8.7*10 À8 W À1 .…”

“…In this respect CeF 3 surpasses most of the magneto-active crystal media. For example, the largest aperture of a TGG single crystal with quality fit for producing an FI is 40 mm [12].…”

Improved Edge-Defined Film-Fed Growth of Incongruent-Melting Tb3Al5O12 Crystal with High Magneto-Optical and Thermal Performances

“…1−5 As a commercialized magneto-optical crystal, Tb 3 Ga 5 O 12 (TGG) shows a large Verdet constant, high laser damage threshold, and low optical loss in the IR. 6 Compared with the TGG crystal, the Tb 3 Al 5 O 12 (TAG) crystal has a greater magneto-optical performance in the visible and nearinfrared (vis−NIR) wavelength region. 7 The room temperature Verdet constant of the TAG crystal in the 400−1100 nm range is more than 30% larger than that of the TGG crystal.…”

Verdet Constant of Magneto-Active Materials Developed for High-Power Faraday Devices

“…However, the TGG crystal exhibits two major disadvantages: (a) its use in the VIS region is struggling with increasing absorption losses towards the shorter wavelengths [59,61]; and (b) growth of large-aperture TGG crystals is difficult and expensive [59,61,81,82]. Although the manufacturing process was greatly improved during the last decades, the largest aperture TGG-crystal-based FD (to the best of our knowledge) was reported in 2015 by Mironov et al [83], having a 40-mm clear aperture. For a larger-aperture FD, the magneto-active glasses still represent a viable option for a non-repetitive high-power operation.…”