Recently, researchers from Shanghai Institute of Optics and Fine Mechanics (SIOM), Chinese Academy of Sciences (CAS) made new progress in MO crystal materials. The findings have been published in the Journal of the Materials Letters on May 27, 2021.

Magneto-optical (MO) materials have drawn a large amount of attention in a wide area of applications for optical isolators, MO switches, and phase modulators, etc. At present, the commonly used MO crystal is mainly terbium gallium garnet (TGG), but its application in the ultraviolet band is limited due to its cutoff in the ultraviolet band (<400nm). CeF₃ crystal belongs to the hexagonal crystal system and has a wide transmittance band (cutoff wavelength is better than 300nm). It has been reported that it is an important medium for MO devices.

Based on the CeF₃ crystal, the growth and MO properties of the Nd:CeF₃ crystal has been studied. The results show Nd:CeF₃ crystal has good optical properties and higher Verdet constants. The Verdet constants of Nd:CeF₃ crystal at 355nm, 632.8nm and 1550nm are ~674.3 rad/T/m,~148.5 rad/T/m and ~18.2 rad/T/m, respectively. This improved MO performance is correlated to the doping of Nd³⁺ due to the quantum-based super-exchange interaction between Nd³⁺ and Ce³⁺.

On the other hand, the verdet constant can also be improved by the electric dipole transition caused by the splitting of crystal field level after the doping of rare earth ions. Compared with commercial TGG crystal, Nd:CeF₃ crystal has higher Verdet constants in visible and near-infrared bands, and has higher transmittance in the near-infrared region. High Verdet constants and short UV cutoff wavelength make it likely to be used in wide-band MO devices.

The research was supported by the National Natural Science Foundation of China and the Association for the Promotion of Youth.

 Fig. 1. Transmission spectra (a) and the Verdet constant dispersion (b) of Nd: CeF₃, CeF₃ and TGG crystals. (Image by SIOM)

Article website:
https://doi.org/10.1016/j.matlet.2021.130134

Contact:
WU Xiufeng
General Administrative Office
Shanghai Institute of Optics and Fine Mechanics, CAS
Email: xfwu@siom.ac.cn
Web: http://english.siom.cas.cn/