High-resolution compact computational spectrometer using enhanced mode interference in a chaotic multimode fiber

The development of high-resolution, miniaturized, and cost-effective spectrometers remains a critical technical challenge. In this work, we demonstrate a high-resolution computational spectrometer by exploiting the chaotic effects induced in side-polished multimode fibers (MMFs). The polishing breaks the structural symmetry of the circular fiber, thereby efficiently exciting guided modes and causing chaos. By forming a 5-cm-long polished region, a spectral resolution of ∼0.5 nm is achieved, representing a one-third improvement over an unpolished MMF of the same length. Moreover, we develop a spectral reconstruction algorithm that integrates adaptive regularization and the Savitzky–Golay filter, enabling real-time reconstruction with enhanced accuracy and robustness. Compared to the Tikhonov regularization algorithm alone, the proposed method reduces the reconstruction error by 50%. This scheme, which leverages chaotic effects to enhance spectral resolution, offers an effective design strategy for developing high-resolution spectrometers.