# Verdet Constant of Magneto-Active Materials Developed for High-Power Faraday Devices
## 2 Characterization of the Verdet Constant as a Function of Wavelength and Temperature
### NIR-MIR Region (\(\lambda>\) 1100 nm)  
Above 1100 nm, a ferrimagnetic material yttrium iron garnet (YIG) crystal and its RE-substituted compositions represent the established materials for the FDs, as they have been investigated since the 1960s [65, 152]. The RE-substituted iron garnets possess very high Verdet constant [153, 154, 155] and low saturation magnetization [157], which is the main reason for its wide utilization for low-power applications in telecommunications, medical field or integrated magneto-optical devices [4]. Moreover, a high-grade YIG ceramics has been very recently reported [158], possibly enabling fabrication of large-aperture YIG elements in the near future. \begin{table}
\begin{tabular}{c c c c c c} \hline
**Material** & \(F,G\) [**rad**/(Tm)] & \(\lambda_{0}\) [**nm**] & \(|V|\) **at 633 nm** & \(|V|\) **at 1064 nm** & **Reference** & **Additional References** \\ \hline TGG & 820.3, \(-\)6.2 & 239.3 & 130.6 & 37.5 & [45] & [17, 18, 29, 49, 51, 56, 58, 77, 88, 79, 80, 105, 106, 107, 108, 109, 111] \\ MOG04 glass & \(\ddots\)- & - & - & 21.3 *** & [84] & - \\ MOG10 glass & \(\ddots\)- & - & - & 25.6 *** & [84] & - \\ Zinc-cellular glass & \(\ddots\)- & - & 23.8 & 7.6 & [89] & - \\ TSAG & 756.7, \(\cdot\) & 262 & 156.6 & 48.9 & [115] & [37, 41, 112, 113, 114, 115, 116, 117, 118] \\ TAG & \(\cdot\)- & - & 172.7 & \(\sim\)46.5 *** & [93, 96] & [56, 63, 90, 91, 92] \\ Si or Ti:TAG & 925, \(\cdot\) & 259 & 186 & 58.3 & [98] & [99] \\ Ce:TAG & 907.6, \(\cdot\) & 272 & 205.5 & 63.5 & [98] & [94, 95, 96, 97] \\ Pr:TAG & \(\ddots\)- & - & 189.8 & - & [101] & - \\ Hor:TAG & \(\cdot\)- & - & 183 & - & [100] & - \\ Tm:TAG & \(\cdot\)- & - & 189.5 & - & [102] & - \\ NTF & \(\cdot\)- & - & 104.7 & 31.1 & [50] & [119] \\ KTF & \(\cdot\)- & - & 112 & 33 & [72] & [72, 120, 121] \\ Tb\({}_{2}\)O\({}_{3}\) & \(16632,\cdot\) & 284.9 & 422 & 128 & [124] & [122, 123, 125, 126, 127] \\ Dy\({}_{2}\)O\({}_{3}\) & \(\cdot\)- & - & 347.6 & 135.3 & [48] & [128, 129, 130] \\ Ho\({}_{2}\)O\({}_{3}\) & 1941.3, \(\cdot\) & 173 & 178 * & 46.3 & [131] & [47, 132, 133] \\ CeF\({}_{3}\) & 697, \(\cdot\) & 245 & 123 & 39 & [60, 61, 134, 135] \\ NaTb(WO\({}_{4}\))\({}_{2}\) & \(\cdot\)- & - & 155 & 52 & [136] & - \\ TSLAG & 801.6, \(\cdot\) & 258.2 & 160 & 50.2 & [81] & [137] \\ Ce:TGG & 803, \(\cdot\) & 256.2 & 157.3 & 53.2 & [140] & - \\ Ho:TGG & \(\cdot\)- & - & 214.9 & 77.8 & [142] & - \\ Pr:TGG & \(\cdot\)- & - & 200.1 & 68.7 & [141] & - \\ Dy:TGG & \(\cdot\)- & - & 178.6 & 60.2 & [144] & - \\ Tm:TGG & \(\cdot\)- & - & 178.6 & 60.2 & [143] & - \\ TcZ & 320.1, \(\cdot\) & 301 & 174 & 48.5 *** & [148] & [149] \\ Tb\({}_{2}\)Hf\({}_{2}\)O\({}_{7}\) & 716.1, \(\cdot\) & 270.5 & 160 & 50.4 & [150] & - \\ Na\({}_{2}\)Tb\({}_{4}\)MoO\({}_{4}\))\({}_{7}\) & \(\cdot\)- & - & 216 & 65 & [138] & - \\ NaCe(MoO\({}_{4}\))\({}_{2}\) & \(\cdot\)- & - & 203.8 ** & 63.8 & [147] & - \\ LiCaTb(BO\({}_{3}\))\({}_{6}\) & \(\cdot\)- & - & 227 & - & [139] & - \\ TbVO\({}_{4}\) & \(\cdot\)- & - & - & 60 & [145] & - \\ Nd:TbVO\({}_{4}\) & \(\cdot\)- & - & 198 & 71 & [146] & - \\ CeAlO\({}_{3}\) & \(\cdot\)- & - & 270 ** & 79.7 & [151] & - \\ \hline \end{tabular}
\end{table} 
Table 2: A brief overview of magneto-active materials for the VIS-NIR FDs (\(400<\lambda<1100\) nm). The Verdet constant dispersion \(V(\lambda)\) is given by the single-transition model in Equation (13) with the specified \((F,G,\lambda_{0})\)-parameters. The listed \(V\)-values are the absolute values of the Verdet constant, specified in rad\(/\)(Tm). Some of the listed values were measured * at 600 nm, ** at 635 nm, *** at 1060 nm or *** at 1075 nm. \(\cdot\) A function different from the model in Equation (13) for the Verdet constant dispersion may be found in the listed reference. Recently, there have been a few reports on MIR paramagnetic materials as well. The main advantage of using a paramagnetic material is the possibility of fine adjustment of the desired rotation angle by changing the magnetic field applied on the magneto-optical element [129].