Computational studies are used to show that the crystalline structure of Si causes the waveguide Kerr effective nonlinearity, γ, to vary by 10% for in-plane variation of the orientation of a silicon nanowire waveguide (SiNWG) fabricated on a standard silicon-on-insulator wafer. Our analysis shows that this angular dependence of γ can be employed to form a nonlinear Kerr grating in dimensionally uniform SiNWGs based on either ring resonators or cascaded waveguide bends. The magnitude of the nonlinear index variation in these gratings is found to be sufficient for phase matching in four-wave mixing and other optical parametric processes.
© 2011 Optical Society of America
Original Manuscript: January 7, 2011
Revised Manuscript: March 4, 2011
Manuscript Accepted: March 5, 2011
Published: April 13, 2011
Jeffrey B. Driscoll, Richard R. Grote, Xiaoping Liu, Jerry I. Dadap, Nicolae C. Panoiu, and Richard M. Osgood, Jr., "Directionally anisotropic Si nanowires: on-chip nonlinear grating devices in uniform waveguides," Opt. Lett. 36, 1416-1418 (2011)