Title :
Energy loss in a planar waveguide caused by a high refracting and absorbing overlay
Author :
Götz, B. ; Hehl, K. ; Karthe, W. ; Martin, B.
Author_Institution :
Inst. of Appl. Phys., Friedrich Schiller Univ. Jena, Germany
fDate :
9/1/1993 12:00:00 AM
Abstract :
An explanation of the mode behavior in dielectric waveguides with an absorbing, high-refractive-index cladding is given. By considering the total waveguiding system as two separate waveguides, it is possible to attribute the behavior of the complex refractive index of the guided modes to the mixing of the modes of both waveguides. For systems with absorption, so-called quasi-leaky waves are observed in the total system for finite thicknesses of the overlay. For absorptionless systems these leaky waves are found only for infinite thicknesses of the overlay. The occurrence and behavior of these quasi-leaky waves versus the increasing overlay thickness are interpreted. A method for calculating the coupling efficiency of modes at the junction unclad waveguide-clad waveguide, taking into consideration waveguides with absorption, is presented. An experimental method for measuring the absorption coefficient for the guided modes in the cladded waveguide and the coupling losses at the unclad-clad waveguide junction was developed. The measured values are in a good agreement with the theoretical calculations
Keywords :
claddings; integrated optics; optical constants; optical losses; optical waveguide theory; refractive index; absorbing overlay; absorption coefficient; absorptionless systems; complex refractive index; coupling efficiency; coupling losses; energy loss; finite thicknesses; guided modes; high refracting; high-refractive-index cladding; infinite thicknesses; integrated optics; junction unclad; light absorption; mode behavior; optical-waveguide theory; overlay thickness; planar waveguide; quasi-leaky waves; separate waveguides; total waveguiding system; unclad-clad waveguide junction; waveguide-clad waveguide; Absorption; Dielectric losses; Energy loss; Optical attenuators; Optical waveguide theory; Optical waveguides; Planar waveguides; Refractive index; Semiconductor waveguides; Waveguide junctions;
Journal_Title :
Lightwave Technology, Journal of
