Polarization-insensitive speckle spectrometer based on cascaded scattering media

This article proposes a polarization-insensitive speckle spectrometer based on a cascaded structure of short multimode fiber (MMF) and ground glass diffuser (GGD), and conducts experimental verification. Compared with traditional spectrometers based on long MMF, the use of cascaded scattering media composed of short MMF and GGD significantly shortens the physical length of key scattering elements, thereby helping to achieve more compact core components. The random scattering introduced by GGD enhances the diversity and specificity of speckle patterns. This can significantly improve the spectrum encoding capability and the system's robustness to interference. In addition, a spectral reconstruction method based on a multidimensional polarization database has been introduced. This method is based on a multidimensional polarization database and can perform high-precision spectral reconstruction on incident light of any polarization, effectively compensating for changes caused by polarization. This system demonstrates the ability to simultaneously reconstruct multiple unknown polarization state spectra from composite inputs, validating the system's ability to address the problem of signal-to-noise ratio (SNR) deterioration caused by polarization blind point (PBP). This study provides an effective technical approach to address the challenges of stability, resolution, and polarization dependence in speckle spectrometers, and lays the foundation for developing the next generation of compact, stable, and polarization insensitive speckle spectrometers.