Seeded Second-Harmonic Generation in Silicon-rich Nitride

Summary

Demonstrating large second-order nonlinear effects in integrated platforms has been a widely pursued aim. All-optical poling of silicon-nitride (SiN) waveguides is a technique to induce second-order nonlinearities. Here, the pump and its phase-locked second-harmonic lead to the generation of a periodic photocurrent satisfying the quasi-phase-matching condition, giving rise to a DC field and therefore a second-order susceptibility. While generating photocurrent, these fields also increase the photoconductivity, leading to a complex interplay that governs the efficiency of these devices. The material constants have previously been extracted for stoichiometric silicon nitride. This project is based on all-optical poling of silicon-rich silicon nitride waveguides; by the end of the project, the material properties were extracted and compared with stoichiometric silicon nitride.

Main objectives

• Demonstration of all-optical poling in silicon-rich nitride
• Fitting of optical poling traces to the governing equation
• Extraction of the phase of the photocurrent, the photogalvanic coefficient, and the conductivity
• Finding the limitations of the conversion efficiency and comparison with other materials

Supervisor

• Prof. Camille-Sophie Brès (camille.bres@epfl.ch)