Polarization transmission matrix enabled high-accuracy, large-bandwidth speckle-based reconstructive spectrometer

One issue with speckle-based reconstructive spectrometer (RS) is the reduced accuracy of computing output when measuring broadband signals. In this manuscript, we improve the reconstruction accuracy of RS by leveraging the polarization transmission matrix (PTM). Unlike previous works that solely utilize speckle intensity at the end of the multimode fiber facet, we incorporate complete polarization information for higher-quality spectral recovery. By optimizing independent spatial channels, output–input ratio, and speckle contrast, the PTM enables to achieve a spectral resolution of 2 pm over 2000 spectral channels. Experimental results demonstrate that our scheme reduces the broadband spectral reconstruction error by 95% and 66%, compared to scalar transmission matrix and vector transmission matrix.