Magnetoactive media for cryogenic Faraday isolators

Abstract

We analyzed a number of optical media, such as GGG, Nd:YAG, Yb:YAG, fused silica, CaF 2 , Yb:CaF 2 , and CdMnTe, that have not been used, to our knowledge, in the cryogenic Faraday isolator (FI) before. The temperature dependence of the Verdet constant and thermo-optical constants was experimentally investigated for λ ¼ 1:07 μm. We calculated the magneto-optical figure-of-merit and assessed the feasibility of using FI media with multikilowatt average laser power.

TSAG-based cryogenic Faraday isolator

“…A characteristic spatial distribution of depolarization is an azimuthally symmetric picture representing a point at the center with a ring around it [30]. At room temperature, c V is negligibly small and depolarization is determined by c P only (Fig.…”

“…It caused by increasing of, 1 V dV dT that according to (8) leads to c V increasing. A characteristic spatial distribution of c V is an azimuthally symmetric picture representing a point at the center with a ring around it [30] (Fig. 7b).…”

Characterization of the terbium-doped calcium fluoride single crystal

“…5, dashed line), which is typical for traditional magneto-optical media: TGG crystals and magneto-optical glasses (MOG). The comparison with MOG and TGG is made because the pure CaF 2 crystal is diamagnetic and does not show any temperature dependence of the polarization plane rotation angle [19]. Thus, the main contribution to the Faraday effect gives the terbium ions, and this contribution depends on the temperature.…”

“…A number of papers show that the paramagnetic nature of many optical media is stipulated by the presence in their structure of rare earth metals ions, especially terbium [19,[20][21][22]. The present paper gives the optical, magneto-optical and thermo-optical characteristics measurements results of the new medium -calcium fluoride doped with terbium ions (10 at.%).…”

“…The advantages of this medium are the refractive index decrease with the temperature increasing (dn/dT < 0, that makes it promising for the thermal lens adaptive compensation applications), high transparency of the material at an extremely wide wavelengths range (150-9000 nm, that makes it promising for use in near and middle-IR devices), high thermal conductivity (10 W mÁK , that makes it promising for use in high average radiation power devices). However, the capability of using this medium in FIs and CFIs is significantly limited by the fact that pure calcium fluoride is diamagnetic and hence has an extremely low Verdet constant (0.025 deg kOeÁcm [19]). …”