Single acquisition reconstruction of nonlinear susceptibility and Raman tensors at the diffraction limit
Year: 2026
Type: article
Abstract: Quantitative extraction of nonlinear optical tensors at the microscale typically requires sequential polarization scans, mechanical rotations, and careful correction of high-NA polarization distortions. We introduce a single-acquisition tensor metrology approach that simultaneously acquires Raman and second-harmonic generation (SHG) signals and enables rapid reconstruction of both Raman and χ(2) tensors from a single diffraction-limited volume. The central innovation is the use of a tightly focused Bessel–Gauss beam whose intrinsic spatiotemporal structure encodes multiple excitation geometries—normal and finite incidence—within a single measurement. The resulting Fourier-plane SHG pattern contains rich polarization and angular information, eliminating mechanical rotation and reducing acquisition time. Combined with a polarization-preserving dichroic module and graphics processing unit-accelerated ray-tracing global fitting, the method exploits the full two-dimensional SHG emission pattern together with polarization-resolved Raman data. We demonstrate quantitative tensor extraction in LiNbO3 and correlate symmetry breaking across the ferroelectric transition of KH2PO4. This approach establishes rapid, calibration-robust optical tensor tomography for microscale materials.
Source: APL Photonics
DOI: 10.1063/5.0331167
Institutions: University of Geneva, Institute of Physics
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,750
OpenAlex ID: W7163881740