Integrated solid immersion grating microspectrometer with wedge prism correction for visible and near-infrared...

For compact spectrometers, the enduring technical challenge lies in the simultaneous optimization of high optical performance and miniaturization. Here we report a solid immersion grating microspectrometer with wedge prism correction (SIG-W-µSPEC), which realizes both high spectral resolution and a highly compact structure across a broad spectral range. The SIG-W-µSPEC integrates a solid immersion grating (SIG), planar reflectors, an optical wedge, a convex lens, a silicon microslit, and a CMOS linear array sensor into a single optical module. The SIG endows the system with high angular dispersion but inevitably induces focal plane tilt; the optical wedge not only compensates for this tilt with high precision but also effectively compresses the optical path length. Following high-precision encapsulation, the SIG-W-µSPEC achieves an average spectral resolution of 4.4 nm in the 600-1000 nm wavelength range, with an overall volume of merely 0.63 cm³. We applied this device to collect the reflectance spectra of fruits for the prediction of soluble solids content (SSC), yielding a high correlation coefficient (R²=0.941). This ultra-compact spectrometer demonstrates broad application prospects in diverse fields, including agricultural quality monitoring, biomedical sensing, and real-time non-invasive on-site detection.