Parasitic optical phenomena limit power scaling in optical fiber lasers. These phenomena include stimulated Brillouin scattering, stimulated Raman scattering, nonlinear refractive index (n₂)-related wave-mixing phenomena (e.g., four-wave mixing), and transverse mode instability (TMI).

Glass composition impacts these nonlinearities as well as the formation of active optical fibers.¹ For example, silica-clad optical fibers containing an oxyfluoride core in the SrF₂–Al₂O₃–SiO₂ glass family can mitigate nonlinearities. Materially, SrF₂ and Al₂O₃, when added to SiO₂, yield intrinsically low Brillouin and Raman scattering glasses. Further, incorporation of fluorine, through SrF₂, reduces linear and nonlinear refractive indices (n, n₂) as well as the thermo-optic coefficient (TOC), the latter of which reduces the likelihood of TMI.