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Colloquium: Dr. Joerg Schilling | Institut für Physik

In-Person PHYS 401

Location

Physics : 401

Date & Time

March 25, 2026, 11:00 am – 12:00 pm

Description

TITLE: Creating a second order nonlinearity by breaking symmetry: The hunt for x(2) in silicon photonics

ABSTRACT: 
The image is a screenshot of a text-based document, likely an abstract for a scientific talk. The title is "Creating a second order nonlinearity by breaking symmetry: The hunt for $\chi^{(2)}$ in silicon photonics."The abstract covers the following key points:The Problem: Second-order nonlinear processes (like sum- and difference frequency generation) are essential for frequency transformation and quantum computing, but materials like Si, $\text{SiO}_2$, and $\text{Si}_3\text{N}_4$ lack a natural dipolar second-order susceptibility ($\chi^{(2)}$) due to their centrosymmetric structure.Methodology: The talk explores breaking symmetry by applying inhomogeneous mechanical stress and investigating electric-field-induced second-order nonlinearity (EFISH) in materials like silicon-rich nitride ($\text{SiN}_x$) and silicon-rich oxide ($\text{SiO}_x$).Findings: Researchers demonstrated a quasi-$\chi^{(2)}$ value of approximately 60pm/V, which exceeds that of classic nonlinear crystals like $\text{LiNbO}_3$. Predictions suggest values could reach 100pm/V by optimizing silicon content and breakdown fields.Conclusion: Because these materials are compatible with standard CMOS processes, it allows for the creation and control of second-order nonlinearity "by design," providing flexibility for future integrated silicon photonics.
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