K. V. Dukel’skiĭ

Processing large blanks of anisotropic single-mode lightguides with elliptical cladding

This paper discusses the possibility of increasing the diameter of blanks for drawing anisotropic single-mode quartz fiber lightguides by fusing the preblank with a tube, the gap between which, is filled with quartz grits. It is shown that the polarization stability of such lightguides increases as the diameter of the light-fiber increases.

Minimizing the optical losses in anisotropic single-mode lightguides with elliptical boron germanosilicate cladding

This paper discusses how the damping at wavelength 1.55 µm depends on various factors for anisotropic single-mode lightguides with boron germanosilicate elliptical cladding. It is shown that the refractive index of this cladding in the preform has a substantial effect on the optical losses of the lightguides. The thickness of the cladding that isolates the core from the boron-containing glass of the elliptical cladding is optimized. The optical losses to Rayleigh scattering are reduced by doping the core with small additives of moisture. For a lightguide with a glass-fiber diameter of 125 µm in a two-layer polymeric coating, an optical loss level equal to 0.5 dB/km is achieved, with a polarization maintenance of 5×10 -6 m -1 .

Forming protective nanoscale coatings based on Al 2 O 3 (Al 2 O 3 –AlF 3 ) on a glass surface

This paper describes the formation of protective nanoscale (10–15 nm thick) coatings composed of Al2O3 (Al2O3–AlF3) on the surface of glasses, using aqueous and water–alcohol solutions of aluminum nitrate. The effect of the concentration and pH of the solutions and the thickness of the coatings and their structure and spectral properties is investigated.

Frequency conversion of subnanojoule femtosecond pulses in microstructure fibers

We experimentally demonstrate highly efficient multiplex frequency conversion of unamplified subnanojoule femtosecond pulses of Ti:sapphire laser radiation in fused silica microstructure fibers. Nonlinear optical spectral transformation of femtosecond pulses in an array of fused silica threadlike channels in these microstructure fibers results in the generation of isolated anti-Stokes spectral components within the wavelength range of 400–500 nm. An efficiency of frequency conversion of about 20% is achieved for 800-nm pump pulses with an energy of 0.7 nJ and a pulse duration of 70 fs.

Mixed oxide (MgO–Y 2 O 3 ) coatings fabricated on glasses from nitrate solutions

This article describes the formation of nanosize MgO–Y 2O3 protective coatings (10–15 nm thick) on the surface of glasses, using aqueous and water–alcohol solutions of magnesium and yttrium nitrates. Based on the results of electron-microscopic and X-ray-phase analyses, the influence of the thickness of the coating on its structure and morphology has been investigated. It is shown that interaction with the glass substrate plays an important role in stabilizing the amorphous structure of coatings consisting of nanoparticles of metal oxides.

Investigation of the single-mode operating regime of microstructured lightguides with radiation-leakage channels

A comparative analysis has been carried out of the modal composition and radiation-damping spectra in microstructured lightguides based on quartz glass with a large core for transporting powerful light fluxes and differing in the number of cycles of holes around the core. The geometrical parameters of the holey core that promote the propagation regime of the fundamental mode under conditions of differential mode losses have been experimentally determined. It is shown that, in lightguides with a hexagonal cladding structure and less than three cycles of holes, a stable single-mode regime can be achieved for a radiation- damping value greater than 0.1??dB/m at a wavelength of 1550 nm.

Increasing polarization stability of anisotropic single-mode quartz light guides with elliptical stress cladding

In this paper, we discuss the polarization properties of anisotropic single-mode light guides with boron germanosilicate elliptical stress cladding. It is shown that, for light guides with a diameter of 125 μm, an increase of ellipticity of the cladding from 0.53 to 0.6 does not result in a change in birefringence. This phenomenon is due to the distortion of the correct shape of the ellipse. With that in mind, optimizing the design of the light guide will allow us to decrease the h-parameter to 5×10-6  m−1.

Microstructured single-mode lightguides based on the phenomenon of differential mode damping

This paper discusses the modal composition of radiation that propagates along microstructured lightguides with a large-diameter core and a special cladding structure. It is shown that all the designs of optical fibers represented here (lightguides with a displaced core, with a cyclic system of apertures, with C3v symmetry) are distinguished from their traditional counterpart by increased stability of the fundamental mode against bending of the lightguide. The single-mode light-propagation regime is achieved in practice in the indicated structures by making the damping coefficients of the fundamental mode and the higher modes substantially different. It is experimentally established that the main advantage of lightguide structures that combine a large core diameter (20–40 µm) with an increased amount of air contained in the cladding is an extended working spectral range.