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The paper presents a set of methods developed for properties control of new optical crystals based on solid solutions of silver and thallium (I) halides. Crystals and optical products based on them are used for optical and optoelectronic systems in the middle and far infrared range. In this regard, to analyze the properties of new infrared materials, new analysis methods are required, which provide high accuracy and repeatability of the results. The authors have developed methods for studying the optical, mechanical and electrical properties of materials. The studies’ results carried out by these methods for various systems of silver and thallium (I) halides solid solutions are presented.

The work is devoted to the study and development of a non-toxic and non-hygroscopic system of AgBr - AgI crystals. Crystals of this system are non-toxic, non-hygroscopic, flexible, safe for organic tissues and media, which makes them promising for use in medical technologies. During the development of crystals, the phase diagram of this system was refined. On the basis of the phase diagram, the modes of high-purity raw materials' synthesis and single crystals growth are selected. Using the selected modes, single crystals of various compositions were grown and their optical properties were determined, such as the spectral transmission range and refractive indices at the short-wavelength absorption edge and at the wavelength of the CO 2 laser (10.6 µm), The work results are the basis for the technology development for the production of optical products (infrared fibers, lenses, windows, prisms) for use in laser, endoscopic and diagnostic medicine, including in systems for early diagnosis of cancer.

Infrared photonic-crystal fibers (IR PCF) based on AgClxBr l-x and AgBrxIl-x crystals have been developed for operation at a CO 2 laser wavelength (10.6 µm). The prospects of using fiber optics, including those with a photonic structure, in medical technologies as a conductor of laser radiation are considered. The advantages and disadvantages of unjacket and two-layer fibers, as well as the versatility and uniqueness of photonic crystal fibers are shown. The process of designing optical fibers with a photonic structure is presented, from the stages of mathematical and computer modeling to seven-stage extrusion and properties study. In computer simulations, plane wave and finite element methods were used to analyze the band structure and mode analysis, respectively. In the properties' study, a CO 2 laser and a Spiricon Pyrocam III camera were used. The model was verified with a real fiber by measuring the radiation distribution in the far zone. High convergence of simulation results with the fabricated fiber is obtained. Thus, infrared fibers with an increased mode field diameter were obtained, which are flexible, easy to sterilize and safe for humans for medical applications.

n this work, were studied photonic crystal fibers for the mid-infrared range based on the AgBr-TlI crystal system with one, two, and three insert rings. It would be found that with an increase of the inserts number, an intensity rise and the effective area reduction of the mode field are observed.

The work is devoted to obtaining crystalline ceramics highly transparent in the range from 1.0 to 67.0 μm based on two phases of the AgBr - TlI system solid solutions. A complex heterophase medium containing several phases, such as a new crystalline ceramic based on two solid solutions of the AgBr - TlI system, allows combining several functional properties in one material, such as effective transparency in a wide infrared range and high resistance of ceramics to various external factors with manufacturability its production. From the obtained ceramics, various optical products for laser technology can be manufactured by hot embossing.

The article is devoted to the manufacture of fiber bundle for the mid-infrared range by extrusion from crystals of the AgBr - TlBr0.46I0.54 system. The fabricated bundle have improved spectral transmittance, optical loss, and spatial resolution characteristics - the main fiber bundle performance indicators. The basic optical properties of the developed bundles have been studied, allowing us to talk about their applicability in various industries, including as channels for delivering laser radiation.

The article discusses infrared polycrystalline fibers based on the AgCl-AgBr crystals system, which are promising for use in medicine, since they are non-hygroscopic, non-toxic, and easy to sterilize. Mid-Infrared radiation (MIR) is interesting for medical applications, since numerous organic molecules and compounds are absorbed in the wavelength range from 2.0 to 15.0 $\mu$ m. To date, various sources of MIR radiation have been developed, such as IR lasers and IR spectrometers. These devices require fiber optic channels to output an optical signal to provide a non-invasive and safe examination of biological tissues and organic substances. Fibers made on the basis of AgCl-AgBr crystals can be used as such channels, since they have a wide transparency range from 2.0 to 20.0 $\mu$ m without absorption windows, have high mechanical strength and flexibility, and low optical loss. Uncladded and cladded polycrystalline infrared fibers are convenient for use in IR spectroscopy for the study of biological tissues. Photonic crystal fibers are convenient for use as fiber radiation leads, since they provide a small aperture and high transmission power of radiation.

This paper presents the results of a study of the refractive-index dispersion for the AgBr–TlI, AgBr–TiBr0.46I0.54, and AgCl–AgBr crystal systems in the spectral range from 0.4 to 56 µm, along with the results of the development and fabrication of single-mode microstructured IR fibers by extrusion from solid solutions of metal halides. The fibers had a central insert 16 µm in diameter of composition 2.6 mol% TlI in AgBr, located in a matrix of composition 2.3 mol% TlI in AgBr with external diameter 525 µm. Inserts with diameter 16 µm of composition 2.0 mol% TlI in AgB were placed in the matrix in hexagonal order. The distribution of the radiation emitted from the fibers in the far field at wavelength 10.6 µm was studied, along with the influence of local heating of a section of the fiber on the transport of the IR radiation. The mode-field diameter was experimentally estimated as 120±30µm. The fibers were suitable for transporting both laser and thermal radiation from heated objects to a thermal viewer.

This work is devoted to the synthesis and the optical properties study of a new multicomponent heterophase ceramic based on two solid solutions of the AgBr - (TlBr0.46I0.54) system. Ceramics are transparent in the infrared range from 1.0 to 40.0 ÷ 50.0 μm, non-hygroscopic, are photo- and radiation-resistant, flexible, as a result of which various optical products are made from it by hot embossing. © Published under licence by IOP Publishing Ltd. This work was supported by the Russian Science Foundation under grant No. 18-73-10063.

The article investigates the ionic conductivity of the AgCl – AgBr, AgBr – AgI, AgBr – TlBr0.46I0.54 solid solutions’ systems in the temperature range 298–508 K. All crystals were obtained by the authors using the methods of thermozone crystallization-synthesis and Bridgman. Crystals have been developed for various applications in the field of optics and photonics and therefore contain a small amount of impurities. The crystal purity is 99.9999%. The AgCl - AgBr system has been used as a checking system for testing and debugging the operation of the pilot plant. The conductivity of the AgBr – AgI, AgBr – TlBr0.46I0.54 solid solutions’ systems has been studied for the first time. The study revealed the key role of the iodine anion in the conductivity nature of solid solutions. With the iodine’ introduction in form of a silver' (AgI) or thallium' (TlBrxI1-x) compound, an abrupt increase in conductivity was observed in AgBr. Reached values were similar to the superionic conductors’ ones. The obtained results form the basis for the design of optoelectronic devices, solid-state electrolytes, acousto-optics, and are also important for the use of silver halide optics in laser technologies.

The presented work is devoted to the study and development of the technology for obtaining the AgBr – AgI crystals system. Studies have been carried out to study the phase diagram in order to clarify the region of stable solid solutions' existence. Based on the data obtained, the modes were selected and single crystals of various compositions were synthesized. Their main optical properties, such as the spectral transmission range, were investigated and the refractive indices were determined at the wavelength of the short-wave absorption edge and the CO2 laser (10.6 μm). The work’ results are necessary for the manufacture of various structures IR fibers, windows, lenses, and other optical products, which are widely used in different fields of science and technology, including laser, endoscopic, and diagnostic medicine.

This article examines the transmission spectra of crystals based on the AgCl − AgBr, AgBr − TlI, AgBr − TlBr0.46I0.54 (KRS-5), AgBr − AgI systems in the visible, infrared, and terahertz ranges. We've determined the optical characteristics in the terahertz range for polycrystalline plates obtained by hot embossing based on silver and thallium halides' solid solutions. As a study result, silver and thallium (I) halides have demonstrated competitive transmission characteristics both in the visible and infrared spectra also in the THz frequency range. The transmission range for crystals of the AgCl − AgBr system was 0.45–30.0 μm (9.9–666.2 THz) and 250–6000 μm (0.05–1.19 THz) with optical transparency reaching 78%, for crystals of the AgBr − AgI, AgBr − TlI, AgBr − TlBr0.46I0.54 systems, 47.0–60.0 μm (4.9–6.3 THz) and 250–6000 μm (0.05–1.19 THz) with optical transparency reaching 76%. At the same time, in the long-wavelength infrared region from 800 to 6000 μm (0.05–0.37 THz) the absorption coefficient’ value hasn't exceeded 0.1 cm−1 for the AgCl − AgBr crystal system, also lied within 0.1–0.005 cm−1 for the AgBr − AgI, AgBr − TlI, AgBr − TlBr0.46I0.54 crystals systems.

The possibility of application flexible infrared Nanopolycrystalline (PIR) fibers made from radiation-resistant crystal systems AgBr – TlI and AgBr – TlBr0.46I0.54, for contact-less measure temperature bearings of own needs mechanisms and signal temperature transmission from nuclear power plant containment is considered. Radiation resistant allows the use that crystals and PIR fibers in high radiation conditions up to 500 kGy, what opens great opportunities of involving that optical materials in atomics. The class of the presented materials is distinguished by a wide transmission range in the range from 0.4 to 60 µm for crystals and from 2.0 to 25 µm for PIR fibers without absorption window, low optical loss (up to 0,1 dB/m), high flexible. The PIR fibers proposed in this paper are made by extrusion from single crystals of silver and thallium halides and are transparent in the mid-infrared range from 2 to 25 µm, which, according to the laws of Planck and Wien, corresponds to temperatures from +1100 °C to –200 °C.

The article is devoted to the technology for obtaining optical ceramics of AgBr−TlI and AgBr−TlBr0.46I0.54 systems and manufacturing samples with different compositions. The new heterophase crystal ceramics are transparent without absorption windows in the spectral range from 1.0 to 60.0 μm. In the ceramics’ transparency spectra based on the AgBr−TlI and AgBr−TlBr0.46I0.54 systems fusibility diagrams, with an increase in the thallium halides mass fraction, as well as the replacement of the bromine ion with iodine, the maximum transparency shifts to a long infrared region.

The article presents temperature measurement experiments using the infrared thermography method utilizing nanopolycrystalline (PIR) fibers. The authors designed an experimental setup that allows temperature measurement of both reference temperature sources, which were used as liquid and dry-block calibrators, and bodies with known properties, such as transformer oil and Peltier element. The research was carried out on individual PIR fibers with a diameter of 1120 μm and a length of 0.2 and 1.0 m, as well as on a fiber bundle of 16 fibers, each with a diameter of 525 μm and a length of 0.3 m. According to the experiments, linear dependences of the measured temperature of these bodies on the actual values were obtained. The physical sense of the obtained linear dependencies coefficients has been described and equations for calibration of fiber-optic temperature sensors have been presented. Additionally, we considered the thermal images transmission over a fiber bundle, which research has shown a high spatial resolution and confirmed the possibility of conducting fiber thermal flaw detection.

This article presents a fiber-optic channel for delivering infrared (IR) radiation within the range from 2.5 to 25.0 μm. It comprises AgBr – TlBr0.46I0.54 uncladded fibers with an extremely small diameter of 90 μm. In the framework of this study, the infrared crystals of AgBr – TlBr0.46I0.54 system and optical fibers based on them, as well as their properties, are described. The stages of the fiber bundle development are also described: the mathematical evaluation of crosstalk is carried out; the computer simulation of the mode field distribution across the bundle is performed. Based on the numerical results, the geometric parameters of the bundle, enabling the efficient transmission of IR radiation, were selected. The fiber bundle with low crosstalk and high spatial resolution was manufactured.

In this paper, we modeled and fabricated a single-mode microstructured fibre (MOF) based on the solid solution crystals of AgBr–TlI and AgBr–TlBr0.46I0.54 systems. For this purpose, we gained the refractive index dispersion of the given systems in the wavelength range of 19–25 μm. It served as a basis for fibre simulations. The obtained MOF model was 700 μm in diameter; it included 200-μm central insert and 40 quasi-square peripheral inserts with the cross-section of 20 × 20 μm and the pitch of 80 μm and operated in a single-mode regime within the wavelength range of 22–25 μm, while the transmitting range was 2.5–25 μm. It possessed an enlarged mode field when compared to a corresponding single-mode step-index fibre (SIF). This MOF was fabricated using a method, which combines hot pressing and extruding. It was shown that the fundamental mode is tightly confined in the fibre core region. The developed MOF structure may be suitable for producing outputs, splitters, and couplers for various types of solid-state lasers based on semiconductors and gas steam lasers, including ones deployed in a harsh environment.

One of the major and essential classes of transmembrane (TM) receptors, present in all domains of life, is sensor histidine kinases, parts of two-component signaling systems (TCSs). The structural mechanisms of TM signaling by these sensors are poorly understood. We present crystal structures of the periplasmic sensor domain, the TM domain, and the cytoplasmic HAMP domain of the