All optical switching and continuum generation in silicon waveguides.

Area of Science:

• Photonics and optical engineering
• Semiconductor device physics
• Nonlinear optics

Background:

• Cross phase modulation (XPM) is a key nonlinear optical effect.
• Silicon-on-insulator (SOI) waveguides offer a platform for integrated photonic devices.
• Mach-Zehnder interferometers (MZIs) are fundamental optical components for switching and sensing.

Purpose of the Study:

• To demonstrate the first cross phase modulation-based interferometric switch in SOI waveguides.
• To experimentally investigate the switching performance of the MZI.
• To theoretically analyze the impact of nonlinear effects, including free carrier dynamics, on device performance.

Main Methods:

• Fabrication of SOI waveguides with a Mach-Zehnder interferometric configuration.
• Experimental demonstration of optical switching using a pump laser and a continuous-wave (CW) signal.
• Theoretical analysis of Kerr nonlinearities, free carrier absorption (FCA), free carrier refraction (FCR), and two-photon absorption (TPA).

Main Results:

• Successful experimental demonstration of CW signal switching approximately 25 nm away from the pump laser.
• Observation that Kerr nonlinearities dominate at low peak power levels.
• Identification of free carrier effects (FCA, FCR) as dominant at higher input power levels.
• Theoretical analysis showing the influence of free carrier generation on continuum generation and power transfer.

Conclusions:

• The developed SOI MZI switch effectively utilizes cross phase modulation for signal switching.
• Understanding free carrier effects is crucial for optimizing performance at high power levels in SOI photonic devices.
• The study provides insights into nonlinear phenomena in SOI waveguides, relevant for integrated photonic applications.