Stress measurements in silicon photonics by integrated Raman spectroscopy

TL;DR

This paper introduces a novel application of integrated Raman spectroscopy to measure and analyze the stress tensor in silicon photonic waveguides, addressing challenges in 3D integrated photonics.

Contribution

It is the first to characterize the stress tensor in silicon waveguides using IRS, providing experimental validation and comparison with simulations.

Findings

Stress tensor measurements agree with simulations

IRS effectively detects stress in nanometer-scale features

Enhanced understanding of stress effects in 3D photonic integration

Abstract

Complex 3D integration of photonic and electronic integrated circuits is of particular interest to carry the photonics roadmap and to address challenges but involves mechanical stress, often detrimental for the behavior of optical components. Existing experiments failed to carefully analyze the stress in such integrated optical devices due to the requirement in terms of feature sizes, few hundreds of nanometers, and 3D-stacked integration. We present for the first time the characterization of the stress tensor of a silicon waveguide using Integrated Raman Spectroscopy (IRS). This experimental technique is directly sensitive to the effective stress, which involves changes in optical properties of the guided mode, at the working wavelength and polarization state of the photonic component. The experimental stress tensor is in good agreement with simulations.