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

Abstract

We review the progress in the investigation of the Verdet constant of new magneto-active materials for the Faraday-effect-based devices used in high-power laser systems. A practical methodology for advanced characterization of the Verdet constant of these materials is presented, providing a useful tool for benchmarking the new materials. The experimental setup used for the characterization is a flexible and robust tool for evaluating the Faraday rotation angle induced in the magneto-active material, from which the Verdet constant is calculated based on the knowledge of the magnetic field and the material sample parameters. A general model for describing the measured Verdet constant data as a function of wavelength and temperature is given. In the final part of this review, we present a brief overview of several magneto-active materials, which have been to-date reported as promising candidates for utilization in the Faraday devices. This overview covers room-temperature investigations of the Verdet constant of several materials, which could be used for the ultraviolet, visible, near-infrared and mid-infrared wavelengths.

Faraday Rotation of Dy2O3, CeF3 and Y3Fe5O12 at the Mid-Infrared Wavelengths

“…The method used for the Faraday rotation dispersion characterization is a modified version of the polarization-stepping technique. The method has been already described in a great level of detail [ 18 , 31 , 41 ] and, hence, we are going to describe only its basic principles within the scope of this study. A simplified scheme of the experimental setup is depicted in Figure 2 .…”

“…The basic requirements on an efficient magneto-active material are to exhibit a high Faraday rotation, which is represented by the Verdet constant or the specific Faraday rotation parameters, and low absorption at the incident laser wavelength. In the case of a Faraday device designed for a high average power laser, the list of the material parameters which needs to be further assessed incorporates the thermo-optical, thermo-mechanical and elasto-optical properties of the material [ 16 , 17 , 18 , 19 ].…”

“…While a lot of scientific effort has been already put into the investigation of the magneto-active materials for the visible and near-IR wavelengths, the options for the mid-IR wavelengths are still very limited [ 18 ]. The materials used for the near-IR wavelengths usually include Tb ions (e.g., the terbium-based garnets, fluorides or sesquioxides have been reported [ 20 , 21 , 22 , 23 ]), which have strong absorption in the mid-IR and, therefore, cannot be used.…”

Up‐And‐Coming Advances in Optical and Microwave Nonreciprocity: From Classical to Quantum Realm

“…The typical values of the Verdet constant [] are: for Tb 3 Ga 5 O 12 (TGG) at 333–750 THz, [ 102,103 ] for Bi‐doped YIG at 385–553 THz, [ 104 ] for Rb vapor at 385 THz, [ 105 ] and at the order of few thousands in YbBi:YIG at 170–300 THz. [ 106 ] For Verdet constants of other magneto‐active materials, we refer to the study by Vojna et al [ 107 ]…”

Growth Peculiarities and Properties of KR3F10 (R = Y, Tb) Single Crystals

“…KY 3 F 10 (KYF) single crystals, as the best studied representatives of this large KR 3 F 10 family, have acquired practical importance as a construction optical material and a laser matrix for various rare-earth ion doping [4][5][6][7][8][9][10][11][12][13][14][15]. Another prospective representative, KTb 3 F 10 (KTF) crystal, is the next generation magneto-optical material for the visible and near infrared optical Faraday isolators [16][17][18][19]. In contrast to Tb-based fluoride crystals such as TbF 3 and LiTbF 4 , this material is optically isotropic and has serious advantages over the traditionally used magneto-optical terbium-gallium garnet crystals due to their excellent thermo-optical performance.…”