We report on the analysis of electroabsorption in thin GaAs/Al0.3Ga0.7As nanophotonic waveguides with an embedded p–i–n junction. By measuring transmission through different lengths, we derive propagation loss as a function electric field, wavelength, and temperature. The results are good agreement Franz–Keldysh model extending over 200 meV below GaAs bandgap, i.e., wavelength range 910–970 nm....