  We comment on the model proposed by Orenstein and Dodge in
arXiv:1506.06758v1, which describes time-domain terahertz measurements of
transiently generated, high-electron-mobility (or superconducting) phases of
solids. The authors' main conclusion is that time-domain terahertz spectroscopy
does not measure a response function that is mathematically identical to the
transient optical conductivity. We show that although this is correct, the
difference between the measured response function and the microscopic optical
conductivity is small for realistic experimental parameters. We also show that
for the experiments reported by our group on light-induced superconducting-like
phases in cuprates and in organic conductors, the time-domain terahertz yields
a very good estimate for the optical conductivity.
