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The narrow-line spectra of transitions within the 4f N shell of triply ionized RE elements cover the entire visible and infrared range. Very small random lattice strains characterizing the quality of a crystal can be detected using anticrossing points.Ĭrystals doped with rare-earth (RE) ions exhibit very narrow homogeneous and inhomogeneous linewidths of the 4f N–4f N optical transitions, since the 4f N electronic shell is well shielded from the crystalline environment by the filled 5s and 5p shells. This fact together with a large value of the magnetic g factor of several crystal-field states creates prerequisites for developing magnetic field sensors, which can be in demand in modern quantum information technology devices operating at low temperatures. The narrowest spectral linewidth is only 0.0022 cm −1. This is the first observation of the resolved hyperfine structure and anticrossing hyperfine levels in the luminescence spectra of a crystal. Here, a well-resolved hyperfine structure in the photoluminescence spectra of LiYF 4:Ho single crystals and the anticrossings of hyperfine levels in a magnetic field are demonstrated using a self-made setup based on a Bruker 125HR high-resolution Fourier spectrometer.
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Resolved hyperfine structure and narrow inhomogeneously broadened lines in the optical spectra of a rare-earth-doped crystal are favorable for the implementation of various sensors.