  Mid-infrared (mid-IR) spectroscopy is a crucial workhorse for a plethora of
analytical applications and is suitable for diverse materials, including gases,
polymers or biological tissue. However, this technologically significant
wavelength regime between 2.5-10$\mu$m suffers from technical limitations
primarily related to the large noise in mid-IR detectors and the complexity and
cost of bright, broadband mid-IR light sources. Here, using highly
non-degenerate, broadband photon pairs from bright spontaneous parametric
down-conversion (SPDC) in a nonlinear interferometer, we circumvent these
limitations and realise spectroscopy in the mid-IR using only a visible (VIS)
solid-state laser and an off-the-shelf, commercial near-infrared (NIR) grating
spectrometer. With this proof-of-concept implementation, covering a broad range
from 3.2$\mu$m to 4.4$\mu$m, we access short integration times down to 1s and
signal-to-noise ratios above 200 at a spectral resolution from 12cm$^{-1}$ down
to 1.5cm$^{-1}$ for longer integration times. Through the analysis of polymer
samples and the ambient CO$_2$ in our laboratory, we highlight the potential of
this measurement technique for real-world applications.
