All-fiber high-accuracy reconstructive spectrometer based on differential polarization division multiplexing

This study introduced a differential polarization division multiplexing (DPDM) scheme for all-fiber high-accuracy spectral measurement.Launching two orthogonal linearly polarized light beams into multimode fibers, the DPDM elegantly reconstructs the input spectra from the differential speckle, which is more comprehensive spectral-to-spatial encoding with fewer noises and better contrast.A spectral measurement with 2 pm resolution and 2000 channels was achieved.Compared with traditional transmission matrix and polarization division multiplexing schemes, the proposed DPDM approach reduced the spectral reconstruction error by 77% and 69%, respectively, offering a simple and effective solution for highly accurate spectral measurements.