A new method for measuring the spectrum of surface roughness based on Bragg scattering, is proposed. This method is characterized by its high precision of measurement of the spatial amplitudes and frequencies. Was determined the rang of spatial frequencies (periods) of harmonics in the roughness spectrum surfaces (0,π) (0; π). When the rotation´s angle of grating is (0,π/4) will be a forward scattering or Bragg´s deflector. At rotation´s angle of grating is (π/2,π/4) or (-3π/4,-π/2) will a Bragg´s mirror. The measurements are made in a gradient waveguide, obtained by ion exchange method.
Determining the mean square deviation σ of surface roughness and the imaginary part of permittivity n''of a planar gradient optical waveguides n(y)= n3+Δn'(y)+ in''(y) = n'(y)+ in''(y), using the integral waveguide scattering method. For experiment two samples are prepared. The first sample using exchange with silver ions and obtained a parabolic profile, subsequently the method of solid-state diffusion of lead oxide in the glass substrate provides a waveguide with a Gaussian distribution profile permittivity. In both cases, laser radiation is used with a wavelength of 0.6328 microns.
We develop the analysis of a structure formed by two planar gradient optical waveguides coupled into a dielectric substrate. Using the numerical method named α κ, matrix equation is developed, to obtain the eigenvalues and eigenvectors that describes the critical frequency and wave modes for different levels of asymmetry of the coupled waveguide.