Faraday isolator with composite terbium gallium garnet TGG/sapphire magneto-optical elements that were produced by the surface-activated direct bonding method was created. Thermally induced ...depolarization and thermal lens for composite elements were investigated experimentally and numerically. The resulting structures operated successfully at a high radiation power, providing an isolation ratio exceeding the classical single element made of TGG by 5 dB and amounted to 34 dB at a laser power of 700 W. The maximum operating power at which the isolation ratio was higher than 30 dB was estimated to be over 2 kW, which is almost 3 times more than in the case of a single TGG.
Tb3Al5O12 (TAG) ceramics with high optical quality were fabricated successfully by a solid‐state reaction method combined with hot isostatic pressing (HIP) post‐treatment. The microstructure, optical ...transmittance, Verdet constant, and thermo‐optical properties were investigated. The obtained TAG ceramics showed a dense microstructure, and the in‐line transmittance reached 82.8% at 1070 nm after laser‐grade polishing. The Verdet constant of TAG ceramics was measured to be 50.9 rad·T1·m−1 at 1070 nm, which is higher than that of commercial Tb3Ga5O12 crystals. The Faraday isolator based on TAG ceramics can provide an isolation ratio of 30 dB with a laser power of more than 1 kW. With excellent optical quality, high Verdet constant, and maximum working power, TAG transparent ceramics are promising for applications of kilowatt‐level Faraday isolators.
A cycle of works on manufacturing and studying laser and magnetooptical ceramics with a focus on their thermo-optical characteristics performed by the research team is analyzed. Original results that ...have not been published before such as measurements of the Verdet constant in the Zr:TAG, Re:MgAl2O4, and ZnAl2O4 ceramics are also presented.
Magnetoactive materials are of considerable current interest, primarily for applications in nonreciprocal Faraday devices used for polarization control, optical isolation, optical switching, and ...modulation. The need for such devices is growing with laser power enhancement. They reduce risk of self-excitation of the amplifiers and optical elements damage and are a handy tool for organizing multipass schemes. However, at high average power of radiation these devices are subject to thermally induced effects that impair their operability and lead to increased losses and to the formation of phase distortions in the transmitted radiation. One of the methods to reduce thermally induced effects is to use in Faraday devices new magnetoactive materials with better thermo-optical properties. This paper is devoted to the study of thermo-optical and magneto-optical characteristics of a unique magnetoactive material-a terbium scandium aluminum garnet (TSAG) crystal. The TSAG has an extraordinary value of optical anisotropy parameter ξ, a Verdet constant 25% higher than the traditionally used terbium gallium garnet crystal and the highest magneto-optical figure-of-merit known in magnetoactive materials at the moment.
•We investigate new magnetoactive medium-terbium-doped (10at.%) calcium fluoride.•The Verdet constant dependences on radiation wavelength and temperature are studied.•Transmission, thermal ...conductivity, thermally induced depolarization are measured.•Estimations show workability of Tb:CaF2-based Faraday isolator at 5kW laser power.•Estimations show workability Tb:CaF2-based cryogenic FI at 20kW laser power.
Optical, thermo-optical and magneto-optical characteristics of the terbium-doped (10at.%) calcium fluoride sample were investigated. It was made the analysis, confirmed the possibility of development of a Faraday isolator and a cryogenic Faraday isolator based on the studied medium, which will provide more than 30dB isolation ratio of laser radiation in the “eye-safe” wavelength range (1530–1620nm) at the 5 and 20kW power, respectively.
Abstract Tb 3 Al 5 O 12 (TAG) ceramics with high optical quality were fabricated successfully by a solid‐state reaction method combined with hot isostatic pressing (HIP) post‐treatment. The ...microstructure, optical transmittance, Verdet constant, and thermo‐optical properties were investigated. The obtained TAG ceramics showed a dense microstructure, and the in‐line transmittance reached 82.8% at 1070 nm after laser‐grade polishing. The Verdet constant of TAG ceramics was measured to be 50.9 rad·T 1 ·m −1 at 1070 nm, which is higher than that of commercial Tb 3 Ga 5 O 12 crystals. The Faraday isolator based on TAG ceramics can provide an isolation ratio of 30 dB with a laser power of more than 1 kW. With excellent optical quality, high Verdet constant, and maximum working power, TAG transparent ceramics are promising for applications of kilowatt‐level Faraday isolators.
Thermo-optical and magneto-optical characteristics of a uniaxial CeF3 crystal have been investigated. Its optical anisotropy parameter, magneto-optical figure of merit, and the ratio of the ...thermo-optical constants P and Q have been measured. The found characteristics have been compared with the corresponding values for the TGG crystal. Based on the obtained results it has been concluded that, despite its anisotropy, the CeF3 crystal is promising material for the development of Faraday isolators for high-power lasers.
•Thermo-optical and magneto-optical characteristics of a CeF3 crystal investigated.•Thermally induced depolarization in CeF3 crystal is not worse than that in TGG.•Strength of thermal lens in CeF3 crystal several times less than that in TGG.•CeF3 crystal is promising material for Faraday isolators for high-power lasers.
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