Contents lists available at ScienceDirect Journal of Non-Crystalline Solids journal homepage: www.elsevier.com/locate/jnoncrysol Magneto-optical properties of high-purity zinc-tellurite glasses A.I. Yakovlev a,⁎ , I.L. Snetkov a , V.V. Dorofeev b , S.E. Motorin b a Institute of Applied Physics of the Russian Academy of Sciences, 46 Ulyanov str., Nizhny Novgorod, Russia b G.G. Devyatykh Institute of Chemistry of High-Purity Substances of the Russian Academy of Sciences, 49 Tropinin str., Nizhny Novgorod, Russia ARTICLE INFO Keywords: Tellurite glasses Hydroxyl groups Crystallization stability Magneto-active materials Faraday rotation ABSTRACT High-purity TeO 2 –ZnO, TeO 2 –ZnO–Na 2 O and TeO 2 –ZnO–La 2 O 3 –Na 2 O glasses have been characterized in terms of material applicability for magneto-optical devices. Glasses with extremely low content of absorbing impurities of 3d-transition metals and hydroxyl groups have been prepared inside a sealed silica glass chamber in a flow of purified oxygen. Magneto-optical properties, including spectral dependence of the Verdet constant in the 450–1561 nm range and magnetic figure of merit, crystallization stability and optical properties in the IR range were studied. 1. Introduction Bulk and fiber devices using the Faraday effect, such as rotators and isolators, are important components of laser systems. They allow con- trolling radiation polarization, creating multipass generation schemes, and transmit radiation in a needed direction. Application of these de- vices in optical laser schemes operating at different wavelengths and with different beam apertures demands magneto-optical active ele- ments with a broad emission spectrum and large aperture. For fabri- cating bulk devices, crystalline materials are used traditionally. However, it is a rather complicated and costly task to grow a crystal of large size and high quality. Ceramics and glasses possessing merits such as isotropy of properties, low cost, relative simplicity of synthesis and fabrication of optical elements of high optical quality may be alter- native materials. The most important merit of glass-like materials is a feasibility of producing magneto-active fiber optical waveguides of different types [1–5] and bulk optical elements [3,4,6]. Such devices may be used for fabricating magneto-optical Faraday rotators and iso- lators and magnetic and electric field sensors, modulators, switches, and fiber-optic Bragg gratings. Thus, glasses must have a rather high value of Verdet constant, good mechanical strength, wide transmission spectral band and low optical losses. One of the types of such magneto- active glasses is TeO 2 -based glass doped by other oxides that has a wide transmission spectral band 0.4–5.5 μm. The value of the Verdet con- stant of tellurite glasses could be modified by changing the con- centration of Zn, Mo, W and La oxides [7–10]. Long enough bulk samples of crystallization-stable tungstate-tellurite and zinc-tellurite glasses containing sodium, lanthanum, molybdenum and bismuth oxides as modifying components with low optical losses have been obtained [11]. The possibility of fabricating high-purity tungstate-tell- urite and zinc-tellurite large bulk, striae-free samples of glass shaped as cylinders having a diameter of 8–12 mm and a length of 90 mm was demonstrated [8,12], also, massive zinc-tellurite optical elements could be produced [6]. As was mentioned above, one of the important requirements for optical materials is a wide transmission band and a low content of impurities. Application of source reagents of special purity and dedi- cated dehydration procedure permitted attaining extremely low total impurity content of 3d-transition metals (0.2–2 ppm wt), absorption by hydroxyl groups (0.001–0.002 cm -1 near the band maximum of ~3 μm) and, hence, low optical losses. Low optical losses on absorption in bulk samples determined by laser calorimetry were less than 200, 90 and 100 dB/km at the wavelengths of 1.06, 1.56, and 1.97 μm, re- spectively. Scattering losses determined by laser ultramicroscopy were low and reduced critically with increasing wavelength. In addition, tellurite glasses are very good candidates for applications in fiber op- tics. Step-index optical fibers with low optical losses as well as micro- structured fibers for supercontinuum generation were successfully fabricated from tellurite glasses [9,13–15]. Also, thanks to the negative value of thermooptical constant Q [16] optical elements made of tellurite glass may be used in compensating of thermally induced depolarization schemes without using a reciprocal quartz rotator [17], that allows simplification and size minimization of the optical scheme. Also, high-aperture optical elements made of this type of glass [6] allow using them in optical systems that operate with high-aperture beams. The value of the Verdet constant of the tellurite glasses with various compositions were previously studied for the 550–950 nm range [1] http://dx.doi.org/10.1016/j.jnoncrysol.2017.08.026 Received 6 April 2017; Received in revised form 23 June 2017; Accepted 15 August 2017 ⁎ Corresponding author. E-mail address: alexey.yakovlev@ipfran.ru (A.I. Yakovlev). Journal of Non-Crystalline Solids xxx (xxxx) xxx–xxx 0022-3093/ © 2017 Elsevier B.V. All rights reserved. Please cite this article as: Yakovlev, A.I., Journal of Non-Crystalline Solids (2017), http://dx.doi.org/10.1016/j.jnoncrysol.2017.08.026