Stimulated Brillouin scattering in nanoscale silicon step-index waveguides: a general framework of selection rules and calculating SBS gain
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Soljacic_Stimulated brillouin.pdf
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Author(s)
Qiu, Wenjun
Rakich, Peter T.
Shin, Heedeuk
Dong, Hui
Soljacic, Marin
Wang, Zheng
Date Issued
December 2013
Journal
Optics Express
Publisher
Optical Society of America
Citation
Qiu, Wenjun, Peter T. Rakich, Heedeuk Shin, Hui Dong, Marin Soljačić, and Zheng Wang. “Stimulated Brillouin Scattering in Nanoscale Silicon Step-Index Waveguides: a General Framework of Selection Rules and Calculating SBS Gain.” Optics Express 21, no. 25 (December 16, 2013): 31402.
Version
Original manuscript
Abstract
We develop a general framework of evaluating the Stimulated Brillouin Scattering (SBS) gain coefficient in optical waveguides via the overlap integral between optical and elastic eigen-modes. This full-vectorial formulation of SBS coupling rigorously accounts for the effects of both radiation pressure and electrostriction within micro- and nano-scale waveguides. We show that both contributions play a critical role in SBS coupling as modal confinement approaches the sub-wavelength scale. Through analysis of each contribution to the optical force, we show that spatial symmetry of the optical force dictates the selection rules of the excitable elastic modes. By applying this method to a rectangular silicon waveguide, we demonstrate how the optical force distribution and elastic modal profiles jointly determine the magnitude and scaling of SBS gains in both forward and backward SBS processes. We further apply this method to the study of intra- and inter-modal SBS processes, and demonstrate that the coupling between distinct optical modes are necessary to excite elastic modes with all possible symmetries. For example, we show that strong inter-polarization coupling can be achieved between the fundamental TE- and TM-like modes of a suspended silicon waveguide.
MIT Department
Massachusetts Institute of Technology. Department of Physics
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DOI of Published Version
https://doi.org/10.1364/oe.21.031402
