Polarization-insensitive speckle spectrometer based on cascaded scattering media.

Area of Science:

• Optics and Photonics
• Spectroscopy
• Fiber Optics

Background:

• Traditional spectrometers face challenges with stability, resolution, and polarization dependence.
• Achieving compact spectrometer designs often requires shortening key optical components.

Purpose of the Study:

• To develop a polarization-insensitive speckle spectrometer with enhanced compactness and performance.
• To improve spectral reconstruction accuracy and robustness to interference.

Main Methods:

• Utilizing a cascaded structure of short multimode fiber (MMF) and ground glass diffuser (GGD) for enhanced scattering.
• Implementing a spectral reconstruction method based on a multidimensional polarization database.
• Experimental verification of the proposed spectrometer design.

Main Results:

• Significant shortening of physical scattering elements for a more compact spectrometer.
• Enhanced spectrum encoding capability and robustness to interference due to GGD scattering.
• High-precision spectral reconstruction for incident light of any polarization, compensating for polarization-induced changes.
• Successful simultaneous reconstruction of multiple polarization state spectra, addressing signal-to-noise ratio deterioration caused by polarization blind points (PBP).

Conclusions:

• The proposed cascaded MMF-GGD structure offers an effective approach for compact and stable speckle spectrometers.
• The multidimensional polarization database method enables robust and accurate spectral reconstruction, overcoming polarization sensitivity.
• This work lays the foundation for next-generation compact, stable, and polarization-insensitive speckle spectrometers.