The effect of electric-field strength on the binding energy of a hydrogenic impurity in an InAs/GaAs quantum wire is discussed. Calculations have been performed using Bessel functions as an orthonormal basis within a single-band effective-mass approximation. The electric-field-induced photoionization cross section of the hydrogenic impurity is investigated. The total optical absorption and the refractive-index changes as a function of normalized photon energy between the ground and the first excited state under the influence of an electric field are analyzed. The optical absorption coefficients and the refractive-index changes strongly depend on the incident optical intensity and the electric-field intensity.