We use optical Faraday rotation (OFR) to probe nuclear spins in real time at high-magnetic field in a range of diamagnetic sample fluids.Comparison of OFR-detected NMR spectra reveals a correlation between the relative signal amplitude and the fluid Verdet constant, which we interpret as a manifestation of the variable detuning between the probe beam and the sample optical transitions. The analysis of chemical-shift-resolved, optically detected spectra allows us to set constraints on the relative amplitudes of hyperfine coupling constants, both for protons at chemically distinct sites and other lower-gyromagnetic-ratio nuclei including carbon, fluorine, and phosphorous. By considering a model binary mixture we observe a complex dependence of the optical response on the relative concentration, suggesting that the present approach is sensitive to the solvent-solute dynamics in ways complementary to those known in inductive NMR. Extension of these experiments may find application in solvent suppression protocols, sensitivityenhanced NMR of metalloproteins in solution, the investigation of solvent-solute interactions, or the characterization of molecular orbitals in diamagnetic systems. N uclear Magnetic Resonance is one of the leading analytical tools among material scientists, organic chemists, and structural biologists. One of its main advantages is the spectral dispersion resulting from system-specific chemical shifts, and from dipolar, quadrupolar, and J-couplings (1). In a typical inductively detected NMR spectrum the relative amplitude of a resonance is given by the fraction of nuclei associated with a particular functional group. The greater natural abundance and higher gyromagnetic ratio of protons make 1 H NMR the most sensitive, a feature that has led spectroscopists to develop various schemes of polarization or coherence transfer to more efficiently detect other less favorable nuclei. Conversely, selective deuteration and solvent suppression schemes are the traditional tools at hand to highlight weaker proton resonances from molecules in solution.Unlike inductive detection, where nuclear spins interact directly with a pick-up circuit tuned to the Larmor frequency, optical schemes in general rely on electrons as intermediaries. The resulting signal amplitude depends on the hyperfine coupling between electrons and nuclear spins on the one hand, and on the interaction between electrons and optical photons on the other (the so-called oscillator strength of the system at a given illumination wavelength). Favorable conditions are typically met in select atomic vapors (2-4) and condensed matter systems (5, 6), which explains why optical schemes, normally designed to monitor the sample fluorescence or absorption, have not yet enjoyed a more widespread use. Recent experiments, however, indicate that optical Faraday rotation (OFR) can serve as a more general platform applicable, in principle, to all transparent condensed matter systems. Initial studies based on a continuous wave (cw) protocol demonstrated OFR-base...