High-resolution miniaturized speckle spectrometry using fuse-induced fiber microvoids

Miniaturized spectrometers with high resolving power and cost-effectiveness are desirable but remain an open challenge. In this work, we repurpose a fiber generated by the catastrophic fuse effect and ingeniously harness it for a speckle-based computational spectrometer. Without complex disorder engineering, the axially random micro-cavities in the fused fiber enhance the wavelength sensitivity of multimode interference, enabling a 10 cm fiber to achieve a spectral resolution of 0.1 nm. This performance exhibits sixfold improvement over a common multimode fiber configuration of the same length. Furthermore, we develop a spectral reconstruction method that combines a weighted transmission matrix with automatic differentiation, which reduces the reconstruction error by approximately half and enhances the peak signal-to-noise ratio by 6.12 dB compared to traditional Tikhonov regularization. Spectra spanning a 40 nm range, exhibiting both sparse and dense characteristics, are accurately reconstructed. To the best of our knowledge, this represents the first application of fused fiber in computational spectrometers, demonstrating its potential for a wide range of spectral measurement scenarios.