Rigorous characterization of acoustic-optical interactions in silicon slot waveguides by full-vectorial finite element method.

S Sriratanavaree,B M A Rahman,N Kejalakshmy,K T V Grattan,D M H Leung

doi:10.1364/oe.22.009528

Abstract

For the first time detailed interactions between optical and acoustic modes in a silicon slot waveguide are presented. A new computer code has been developed by using a full-vectorial formulation to study the acoustic modes in optical waveguides. The results have shown that the acoustic modes in an optical slot waveguide are not purely longitudinal or transverse but fully hybrid in nature. The model allows the effects of Stimulated Brillouin Scattering and the associated frequency shift due to the interaction of these hybrid acoustic modes with the fully hybrid optical mode also to be presented.

Highlights

The field of silicon photonics allows both the exploitation of standard Complementary MetalOxide-Semiconductor (CMOS) fabrication techniques and integration of photonics with microelectronics allowing the development of a range of novel devices
A new computer code has been developed by using a full-vectorial formulation to study the acoustic modes in optical waveguides
The results have shown that the acoustic modes in an optical slot waveguide are not purely longitudinal or transverse but fully hybrid in nature

Summary

Introduction

The field of silicon photonics allows both the exploitation of standard Complementary MetalOxide-Semiconductor (CMOS) fabrication techniques and integration of photonics with microelectronics allowing the development of a range of novel devices. Stimulated Brillouin Scattering (SBS) in optical waveguides is an important, but often undesirable nonlinear effect which arises from the coherent interactions between the optical and acoustic modes and limits power scaling in many photonic devices. Guided Acoustic Wave Brillouin Scattering (GAWBS), first studied in 1985 [9], where radial modes can be beneficial or detrimental [10] (as with SBS) but flexural and torsional acoustic modes have been exploited in the development of all-fiber acousto-optic tuneable filters [11]. A rigorous full-vectorial analysis method provides a more accurate characterization of such acoustic wave propagation and a simulation using the versatile Finite Element Method (FEM) has been developed to allow, for the first time, an analysis of acoustic modes and their interactions with the optical modes in slot optical waveguides

Theory

Results

Conclusion