This article presents a framework for new architectures and integration schemes for terahertz modulators with a 1550-nm-pumped InAs-based modulator integrated in a WR1.0 waveguide operating in the 0.75–1.1 THz frequency range. Insertion loss is less than 5 dB, average modulation depth is between 60% and 90%, and the modulation bandwidth is 15 MHz. The fiber technology employed reduces the size of the pump beam and consequently increases the optical density useful for pumping. The smaller pump spot size increases bandwidth while maintaining high modulation depth. A thinner InAs layer grown on lattice-mismatched substrates achieve larger bandwidths, and p-type dopants reduce insertion loss.