We have demonstrated that low‐energy electron irradiation of silica glass leads to a sufficient change in the refractive index to form optical waveguides. A peak enhancement of at least 0.9% is achieved by the deposition of some 1024keV cm−3and is stable to at least 200 °C. This energy requirement is consistent with measurements of lattice compaction in silica which also reaches a maximum value when ∼1024keV cm−3is deposited in ionization or electronic excitations. (The change is thought to be the result of irradiation damage). It is noted that changes induced in this way might have application in both integrated optics and graded index fibers.