Enhancing Nonlinear Kerr effect in Silicon Nitride Waveguides

• Applicant: Professor Kambiz Jamshidi, Ph.D.
• Subject Area: Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
• Term: from 2015 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 267234016

By emerging CMOS compatible silicon photonics platform, more complex functionalities in this platform can be offered and will be demanded. Kerr nonlinearity is an effect which can be used for various optical signal processing applications like optical sampling, parametric amplification, wavelength conversion, etc. So far, this effect has been used in optical fibers, but integrated Kerr nonlinearity can also be exploited in the near future for signal processing purposes. Silicon waveguides have been initially investigated for this purpose but since two photon absorption (TPA) is strong in silicon, accumulated nonlinear phase shift is limited to a few radians. Although, silicon nitride has lower Kerr nonlinear coefficient than silicon, since it has much lower TPA coefficient, it has the potential to provide more accumulated nonlinear phase shift. In this project, it is planned to maximize the accumulated nonlinear phase shift caused by Kerr effect in silicon nitride waveguides. Slow light structures will be investigated to enhance the optical field inside the structure and provide a slowdown factor which would intensify the Kerr nonlinearity. Among the various slow light structures, we will consider corrugated waveguides (one dimensional photonic crystal), two dimensional photonic crystals with line defect and coupled ring resonators. Also a mixed combination of silicon and silicon nitride (since both can be used easily on silicon on insulator wafers in a CMOS fab) will also be investigated to further enhance Kerr nonlinearity coefficient. Analytical models based on an intensive literature review will be used to prepare the design of the slow light structures and intensive numerical simulations will be performed to analyze the designed structures and find their robustness to fabrication tolerance. The designs will be prepared and sent for tape out and finally the fabricated structures will be characterized. We try to find the ultimate limitations of the structures to pave the way for optical signal processing using Kerr nonlinearity in silicon nitride waveguides.

• DFG Programme: Research Grants
• Cooperation Partners: Professor Klaus Petermann, Ph.D.; Professor Dr.-Ing. Dirk Plettemeier