Spectral transmission, reflection, and photocurrent absorption data obtained on gas‐source molecular beam epitaxy grown InGaAs/InP multiple quantum well (MQW) and superlatticep‐i‐ndiode structures demonstrate, for the first time in this materials system, that similar modulation to MQW structures can be achieved using superlattices, but at significantly lower operating voltages. Specifically, we have observed photocurrent absorption changes of as much as 58%, transmission changes of 8.2%, and reflection changes of 32% for applied biases of only 4 V, in nonresonant modulators operating at a wavelength ∼1.5 &mgr;m. These results encourage the possibility of employing such devices in fast, high density optical modulator arrays operating over the 1.3–1.6 &mgr;m range.