Long Period Waveguide Gratings in Planar Gradient Waveguides

This paper introduces the application possibilities of long-period waveguide gratings in planar structures of gradient waveguides. The analysis of resonance possibilities of coupling modes in gradient-gradient structures was carried out. An original configuration of single-mode (gradient) structure and multimode decoupling area was proposed. The refractive properties of gradient areas were calculated on the basis of experimental data relating to the $Ag^{+}$ ↔ $Na^{+}$ ion exchange in soda-lime glass. The calculations of the resonance properties included the actual dispersion of the glass substrate. The influence of the ion exchange technological processes (diffusion, heating) on the character of the coupling modes' curves was also presented. The calculations indicate the possibility of obtaining these resonances in the wavelength range corresponding to the visible spectrum.