Propagation losses in silica-on-silicon optical waveguides— Theoretical analysis and comparison with experimental results

Abstract

Silica-on-silicon optical waveguides are being increasingly used for the design and fabrication of a large variety of optical integrated circuits for applications in optical communication systems. One of the crucial factors in the configuration of these waveguides is the minimum thickness of the buffer layer of silica [between the guiding core layer of doped silica and the silicon substrate] that is required in order to keep the propagation loss of a guided mode, launched in the core and leaking into the substrate, below a specified limit. An earlier analysis by Stutius <i>et </i><i>al.</i> involved the solution of a complex eigenvalue equation

and a perturbation method to calculate the propagation loss in this waveguide structure. Ghatak <i>et </i><i>al.</i> developed a novel 'leaky mode' analysis and a matrix method of numerical analysis to study the propagation of a mode in leaky waveguide structures. The method of Ghatak <i>et </i><i>al</i>. has b<span style="font-size:14.0pt;font-family:Arial;mso-bidi-font-family:" times="" new="" roman";="" color:black"="" lang="EN-IN">een applied in this paper to calculate the propagation losses in silica-on-silicon waveguides, and

<span style="font-size:14.0pt;line-height:115%;font-family:" times="" new="" roman";="" mso-fareast-font-family:"times="" roman";color:black;mso-ansi-language:en-in;="" mso-fareast-language:en-in;mso-bidi-language:hi"="" lang="EN-IN">the results are found to be identical to those obtained by the earlier approach of Stutius et al. The results of calculations by different methods are also compared with experimental results for some typical waveguides.</span></span>