Selectively oxidized single-mode GaAs vertical-cavity surface-emitting lasers are investigated for biased 3-Gb/s and bias-free 1-Gb/s data links. Bit-error rates of better than 10(-11) for pseudorandom data transmission over 4.3 km of standard 1300-nm single-mode fiber are demonstrated, A simple mode filter is used to suppress intermodal dispersion. The requirements of the gigabit ethernet are fulfilled even for bias-free operation.