Fig. 1: Near-infrared spectroscopy needs vs. reconstructive spectrometer performance.

a Overtone absorption bands of typical functional groups in the near-infrared spectrum range. b Performance requirements of various near-infrared spectroscopy applications compared with the metrics of state-of-the-art waveguide-based reconstructive spectrometers. The colored dots represent specific application scenarios. The dashed arrow indicates that sensor performance can be further enhanced by co-packaging two or even more chiplets (see “Discussion” for details).