The observed shift in the maxima of the short-lived center and the dependence of the luminescence spectra on excitation suggest the presence of disorder in the YScO3 crystal fiber matrix of the crystal fiber. The degree of disorder in the optical center II of Yb3+ ions is influenced by the inhomogeneous broadening of the luminescence and absorption lines. In the long-wavelength wing of the Yb 3+ ion luminescence spectrum (Figure ), the bands associated with C II 2 (Y 3+ , Sc 3+ ) symmetrical centers (Fig. ) exhibit varying intensity and spectral position on the 2 F5/2(1′, 2′) → 2 F7/2 and C II 2 (Sc 3+ )), which have a heterogeneous distribution within a single optical center, can also occur (Figure , curve 3). This observation can be attributed to the close proximity and spectral overlap of the Stark energy levels associated with the 2F7/2 → 2F5/2 absorption transition of two distinct optical centers, II(Y3+) and II(Sc3+), with the C2 local symmetry.