Trends, Demand and Development in Optical Fiber Industry Today, in the fiber optic industry, we see high competition, especially in the production of standard telecommunications fiber. However, fast development of high-tech industries requires increasing usage of fiber lasers and a wide variety of fiber optic sensors, and this stimulates research and development constantly. Large-diameter fibers are needed to produce laser cables, for example, delivering laser light to the working area in many factories in different industries at the same time small-diameter fibers are required to make FBG sensors, gyroscopes, medical endoscopic instruments.
High-aperture diffraction optical element shaping techniques based on the use of pendulum-type ruling engines This paper touches upon the features and limitations of shaping techniques and promising application ranges of high-aperture diffraction optical elements. A number of applications require manufacturing ruled high-aperture diffraction optical elements on spherical and aspherical surfaces with a large sag, which is unachievable in practice with the existing manufacturing equipment. Engineering solutions have been suggested that open up the possibility to broaden the range of high-aperture diffraction optical elements basing on the use of pendulum-type ruling engines with subsequent replication of diffraction structure in the polymer layer.
The scope of refractive optics has expanded significantly, significantly covering the area of application of traditional X‑ray optics – crystals and mirrors. But for astrophysical problems, X‑ray optics of squint gliding remains an indispensable tool. The complexity of the problem lies in the manufacture of multilayer interference mirrors, refractive lenses, and tunable refractive lenses – zoom lenses. To use their potential, X‑ray optics of diffraction quality are required. And in the field of X‑ray microtomography, the possibilities of increasing sensitivity are hidden in the use of X‑ray optical elements: capillary lenses, Fresnel zone plates, asymmetric reflecting crystals (Bragg magnifiers), multilayer X‑ray mirrors.
Powerful (up to 100 W) Continuous Laser Arrays for Pumping Solid-state Lasers Powerful high-performance continuous wave (CW) laser arrays, emitting in the spectral range of 808 nm and designed for pumping solid-state lasers, have been developed. The laser arrays have high efficiency of converting electric current to light (more than 50%) and small geometrical dimensions. The chips are manufactured based on heterostructures grown by metal organic chemical vapour deposition (MOCVD) epitaxy. The parameters of the developed LA and the results of their life tests are given in the article.
Micro-Cryogenic Stirling Cooler with a Combined Regenerator and Magnetocaloric Cooling Step The article describes the developed two-stage microcryogenic Stirling system for cryostatting the photodetector module. The design has a rare-earth combined regenerator in the first stage of cooling and magnetocaloric cooling in the second stage. The design provides an extended range of cryostatting temperatures and an increased efficiency near a temperature of 80K.
Optical Backscatter Reflectometry (OBR) Optical communications technology is rapidly evolving to meet the ever-growing demand for ubiquitous connectivity and higher data rates. As signaling rates increase and modulation schemes become more complex, guaranteeing a high-fidelity optical transmission medium is becoming even more critical. Additionally, modern networks are relying more on photonic integrated circuits (PICs) based on silicon photonics or other developing technologies, introducing additional variables into the design and deployment of robust high bandwidth optical systems. Measurement and full characterization of loss along the light path is a fundamental tool in the design and optimization of these components and fiber optic networks. The review considers the difference in optical reflectometry methods. The advantages of optical backscatter reflectometry (OBR) are presented for a number of applications, including short fiber networks and PIC.
Hollow-core revolver fibers (properties, design and fabrication, applications) Hollow-core revolver fibers (RF) are a special type of hollow optical fibers with negative curvature of the core-cladding boundary. Their reflective cladding usually consists of a single layer of capillaries surrounding the hollow core. The physical mechanisms responsible for the waveguide properties of these fibers are discussed. A review of the optical properties and possible applications of hollow-core revolver fibers is given. Particular attention is paid to hydrogen Raman lasers of the mid-IR spectral range based on hollow-core revolver fibers and emitting in the range of 2.9–4.4 μm.
Wavefront: Some Issues Related to its Reconstruction and Shaping in Holography and Diffraction Optics In this paper we consider the problems of wavefronts shaping and transformation in holography and in diffraction optics. The simplest examples illustrate the similarity and difference in the physical nature of the processes of formation and intensity distribution of a single diffractive (holographic) lens and a classical lens for continuous and single-pulse laser radiation in a circle of diffusion. It was also proposed to generalize the theorems of Malus and Levi-Civita in cases of diffraction; the appropriate formula is given.
Experience оf the Development of Heat-resistant, Radiation-resistant and Hydro-resistant Optical Fibre The manufacturing technology of pure-silica-core optical fibre mass production has been developed and mastered. Research for its resistance to elevated temperatures, ionizing radiation and hydrogen-containing medium was conducted. These optical fibres can be used in cables for special telemetry systems, on-board cables for aerospace engineering, and geophysical cables for measuring temperature in a borehole.
Research of optical fiber’s hermetic carbon coatings used in harsh conditions Hermetic carbon coatings of various thicknesses in the range from 1 to 100 nm for optical fibers are characterized by confocal Raman spectroscopy and atomic force microscopy. In the course of the research, standard Raman far-field spectra were obtained in the region from 1000 to 2000 cm−1 using 5 individual components: different types of graphite-like and disordered phases. A new spectroscopic indicator is also proposed, which provides a measure of the soot fraction in carbon materials. Studies using the TERS (tip-enhanced Raman scattering) method confirmed the complex structure of the Raman D band of the first order assigned to disordered vibrations of the graphite lattice. In addition, using this method, it was proved that carbon allotropes are formed in protective coatings, such as carbon nanotubes.