Measurements of the homogeneous width of the
4 G5/2 ,
2 G7/2 ${\mathrm{\ensuremath{-}}}^{4}$
I9/2 transition of
Nd3+ in a silicate glass fiber at low temperatures by the technique of accumulated photon echoes show that the dephasing processes are one-phonon processes between the Stark levels of
Nd3+ . These dephasing processes differ from the commonly observed processes of rare-earth ion-doped glasses: the local-configurational-change-induced dephasing process and the Raman process with low-frequency modes. The densely distributed Stark levels of the
4 G5/2 and
2 G7/2 states are responsible for one-phonon processes. The transition-wavelength dependences of the homogeneous widths ${\mathrm{\ensuremath{\Gamma}}}_{\mathrm{h}}$ (4.2 K) and ${\mathrm{\ensuremath{\Gamma}}}_{\mathrm{h}}$ (T\ensuremath{\rightarrow}0) are explained by using the one-phonon process model.