A tellurium-doped germanosilicate optical fiber was developed by modified chemical vapor deposition and solution doping techniques. Using the continuous-wave self-phase modulation method, the nonresonant nonlinear refractive index, $n_2$ , was measured to be $5.52\times {10}^{-20}{\mathrm{m}}^2/\mathrm{W}$ , which is 2 to 3 times that of the undoped germanosilicate glass fiber. Polyhedron structures $\mathrm{Te}{\mathrm{O}}_3$ and $\mathrm{Te}{\mathrm{O}}_4$ with $\mathrm{Ge}{\mathrm{O}}_4$ and $\mathrm{Si}{\mathrm{O}}_4$ are believed responsible for lower phonon energy, more nonbridging oxygens, and a larger hyperpolarization, leading to the observed higher nonresonant optical nonlinearity.