Measuring the third-order optical nonlinearities in silicon nitride for photonic integrated circuits

Area of Science:

• Photonics
• Materials Science
• Electrical Engineering

Background:

• Nonlinear effects, especially third-order nonlinear effects, are crucial for advanced functionalities in photonic integrated circuits (PICs).
• Understanding these effects is essential for optimizing device performance and enabling new applications.
• The nonlinear response of integrated devices often deviates from bulk materials due to factors like waveguide geometry and light polarization.

Purpose of the Study:

• To investigate and quantify third-order nonlinear effects in silicon nitride PICs.
• To develop and validate a comprehensive model for predicting device behavior under various conditions.
• To establish efficient measurement techniques for characterizing nonlinear susceptibility.

Main Methods:

• Utilized continuous-wave (CW) excitation of silicon nitride racetrack resonators for efficient nonlinear susceptibility measurement.
• Performed complementary optical and electrical simulations of waveguide structures.
• Developed an analytical model using nonlinear coupled equations for racetrack cavities.
• Fitted simulation results to experimental data for model refinement.

Main Results:

• Evaluated the effective third-order nonlinear susceptibility of silicon nitride waveguides.
• Demonstrated that nonlinearities depend on polarization, wavelength, and waveguide dimensions.
• Explored the scaling of the DC-Kerr effect in silicon nitride waveguides.
• Defined optimal conditions (input power, DC voltage) for measuring third-order nonlinear susceptibility.

Conclusions:

• The study provides a deeper understanding of nonlinear responses in PICs, crucial for device design and application development.
• The developed models and measurement techniques enhance the accuracy and efficiency of characterizing nonlinear effects.
• This work contributes to the advancement of silicon nitride-based PICs for various photonic applications.