Investigation of Field and Energy in a Weakly-Conducting Optical Fiber with an Arbitrary Degree of Refractive Index Profile

Introduction. We consider a weakly conductive gradient fiber in the single-mode regime and solve the equation for the electric field in the core of this fiber in a general form in the first approximation. The aim of this study is to study the field and energy in the core of a weakly conductive gradient fiber without taking into account the polarization in the single-mode regime in the case of a power-law (generally) refractive index profile. Materials and Methods. From Maxwell’s equations for dielectric media, there was derived an equation for the field in a fiber with gradient refractive index profile. Making the appropriate substitutions, replacing the zero-order Bessel function with a Gaussian function, and making the necessary approximation of the resulting equation, we arrive at an equation that we solve by the Wentzel – Kramers – Brillouin method and obtain analytical expressions for the field and energy inside waveguide for an arbitrary degree of the refractive index. Results. There was obtained a solution of the equation for the field in fiber with a powerlaw refractive index profile. Numerical calculations were carried out. A graph of the dependence of a dimensionless quantity – “normalized” energy – on the waveguide parameter for the first five powers of the profile (n = 1, 2, 3, 4, 5) was plotted. Discussion and Conclusion. It is shown that the energy increases faster for the profile with n = 1, and after this value, the energy for the profile with n = 1 increases sharply, and for n > 1, the energy growth decreases with increasing n. The results obtained in this work can be used for creating an energy-efficient core, for carrying out a possible analysis of information transmission, and for designing waveguides taking into account specific applications.