Single acquisition reconstruction of nonlinear susceptibility and Raman tensors at the diffraction limit

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.