Title :
Iterative simplex-finite difference method for the characterization of optical waveguides
Author :
Caccavale, Federico ; Gonella, F. ; Caneva, G. ; Mansour, Ibrahim
Author_Institution :
Dipartimento di Fisica, Padova Univ., Italy
fDate :
8/1/1996 12:00:00 AM
Abstract :
A new method is presented for reconstructing smooth refractive index profiles of optical waveguides from measured effective indexes. It is based on the semivectorial finite difference method to solve the polarized wave equation for a given refractive index profile. An iterative simplex algorithm is used to find the best refractive index parameters that give, as a solution, effective indexes close to the measured ones. The method is applied successfully to Ag+-Na + ion-exchanged glass slab waveguides and to diffused Mg/Ti:LiNbO3 slab waveguides. Dopant concentration profiles are obtained by using secondary ion mass spectrometry. The relationship between the refractive index change and the dopant concentration is determined for both cases. The iterative simplex algorithm-finite difference method (ISA-FDM) is compared to other index profile reconstruction methods, and the advantages with respect to WKB-based methods are pointed out
Keywords :
diffusion; finite difference methods; integrated optics; ion exchange; iterative methods; lithium compounds; magnesium; optical glass; optical waveguide theory; optical waveguides; refractive index; secondary ion mass spectroscopy; silver; sodium; titanium; Ag+-Na+ ion-exchanged glass slab waveguides; LiNbO3:Mg,Ti; WKB-based methods; diffused Mg/Ti:LiNbO3 slab waveguides; dopant concentration; dopant concentration profiles; index profile reconstruction methods; iterative simplex algorithm; iterative simplex algorithm-finite difference method; iterative simplex-finite difference method; measured effective indexes; optical waveguides; polarized wave equation; refractive index change; refractive index profile; secondary ion mass spectrometry; semivectorial finite difference method; smooth refractive index profiles; Finite difference methods; Iterative algorithms; Iterative methods; Optical polarization; Optical refraction; Optical variables control; Optical waveguides; Partial differential equations; Refractive index; Slabs;
Journal_Title :
Lightwave Technology, Journal of
