DMD-Based Broadband Correlation Spectroscopy for Chemical Sensing

Correlation spectroscopy (CS) has traditionally relied on distinct, spiky absorption features for analysis. Here, we present a novel broadband CS approach tailored for the detection of samples with broadband spectra. Central to this approach is an arbitrary spectrum generator (ASG), which leverages the tunability of a digital micromirror device (DMD) to produce spectrally oscillating illumination. The ASG disperses light from a broadband light source onto the DMD, which enables high-frequency tuning of the micromirrors to dynamically modulate the output spectrum. The 2f signal generated through broadband spectral oscillation is analyzed to achieve detection of chemicals at ultra-low concentrations. Our proposed approach can suppress noise and mitigate interference from other sample components. Experimental results validate the performance of the system, achieving a detection limit as low as 32 parts per billion (ppb). This method expands the use of CS into the broadband region and unlocks new possibilities for diverse applications.