All-fiber microendoscopic polarization sensing at single-photon level aided by deep learning

We address the problem of precise polarization measurement under challenging conditions. To resolve this problem, we introduce a polarization sensor using scattering in a short optical fiber and deep learning. The breakthrough lies in sparse sampling of the scattered light and single-photon sensitivity. The all-fiber sensor achieves unprecedented accuracy, speed, resolution, and stability. Our results solve a long-standing problem of real-time low-light polarization microsensing, opening new paths in biomedical imaging, material research, and quantum technology.