COSMOS: Correlation‐Optimized Spectral Modulation Optical Sensing

Spectroscopy is a fundamental technique in chemical sensing. Correlation spectroscopy (CS) leverages prior knowledge of the known spectrum and can enhance detection sensitivity by actively illuminating the sample of interest with light of a designed spectral profile. However, existing CS methods are primarily laser‐based, which limits their use to samples with sharp absorption features. In this work, correlation‐optimized spectral modulation optical sensing (COSMOS) is proposed. It uses a digital micromirror device (DMD) to generate various optimized broadband spectra for CS to target samples with broadband absorption. A second‐order derivative (SOD)‐matching theory is introduced to maximize detection efficiency. COSMOS achieves a detection limit as low as 32 ppb for color dyes in solution and exhibits strong resistance to spectral interference, outperforming commercial spectrometers. With its high sensitivity and robustness, COSMOS shows excellent potential for environmental monitoring, biomedical diagnostics, industrial process control, and chemical analysis.