Higher-order modes of photonic-crystal fibers

The propagation constants and the field distribution of the higher-order modes in photonic-crystal fibers have been studied. It is shown that the standard single-mode operation condition of a fiber, in which the first higher-order mode is cut-off, is not applicable to photonic-crystal fibers because the latter can guide higher-order eigenmodes, even when this condition is fulfilled.     

Prism excitation of leaky modes of thin films

The conditions for prism excitation of leaky modes of thin dielectric films are investigated theoretically and experimentally. The possibility of solving the inverse optical problem on reconstruction of parameters of the films guiding the leaky modes of various types are analyzed.     

Choosing the ranges for measuring the reflectivity of a prism coupler in the waveguide spectroscopy of thin films

A criterion for selecting the best ranges for measuring the reflectivity of a prism coupler, based on minimizing the error in reconstructing the parameters of thin films using the least-square method, is proposed. The effectiveness of the criterion is demonstrated by solving the inverse optical problem for a SiO_x film deposited on a silicon substrate as an example.     

Leaky modes of channel waveguides with uniaxial anisotropy

An exact numerical method for analyzing the propagation properties of leaky modes of inhomogeneous channel optical waveguides with a complex uniaxial diagonal permittivity tensor is developed. The method is based on solving the system of integro-differential equations formulated with respect to transversal components of the magnetic field and the longitudinal component of the electric field. Some results of investigation of leaky modes of diffused channel waveguides in LiNbO₃ and LiTaO₃ crystals are given.     

Spectrophotometry of Layers on Plane Parallel Substrates

Optics and Spectroscopy - Integral expressions are obtained for the reflectance and transmittance spectra of a structure that is formed by two thin layers deposited on opposite faces of a...     

Sensitivity of Reflecting Terahertz Sensors of Aqueous Solutions

Technical Physics - Sensitivity of sensors of aqueous solutions in which a terahertz signal is reflected from a structure consisting of a dielectric film and solution is studied. The maximum...     

Optical Characteristics of a Europium-Doped Barium Titanate Inhomogeneous Layer

Optics and Spectroscopy - An algorithm for solving the inverse problem of multiangle spectrophotometry of an inhomogeneous absorbing film is developed, which is based on polynomial representations...     

Method of integral equations in the theory of microstructured optical fibers

A method for designing microstructured optical fibers that is based on exact integral equations for the transverse components of the magnetic field of the mode is proposed. A solution to the vector waveguide problem for fibers with a finite number of circular capillaries in the round cavity of the cladding can be refined successively. Quartz fibers with hexagonal capillary rings are also studied.     

On the problem of reconstruction of permittivity profiles for optical fibers and channel waveguides through the far field of fundamental mode emission

An algorithm for analytic continuation of the Fourier transform for the mode field in a three-dimensional waveguide from a finite region to the entire plane of spatial frequencies is proposed. It is demonstrated that this algorithm makes it possible to reconstruct the permittivity profiles of optical fibers and channel waveguides through the far field of fundamental mode emission with subwavelength resolution.