Fabrication of porous silicon channel waveguides with multilayer Bragg cladding

Abstract

The ability to control the porosity and hence the refractive index of porous silicon makes it an interesting material for photonic applications. Layers with refractive indices as low as 1.5 up to that of bulk crystalline silicon can be easily fabricated by varying the electrochemical etching parameters during anodization. This ability to control the refractive index makes it possible to design waveguides that more closely match the properties of silica based optical fiber, thus reducing insertion loss. In this paper we explore the possibility of using a focused laser in order to create waveguiding regions in porous silicon substrates comprising of multiple layers. The direct write process can be used to locally oxidize the porous material forming micron sized channels that can be used for waveguiding. Various designs are simulated using a finite element mode solver in order to optimize the design parameters for single mode waveguiding. Experimental results showing the effect of laser irradiation on multilayered structures are also presented. © 2010 Copyright SPIE - The International Society for Optical Engineering.