  We studied the superconducting (SC) state depletion process in an electron
doped cuprate Pr$_{1.85}$Ce$_{0.15}$CuO$_{4-\delta}$ by pumping with
near-infrared (NIR) and narrow-band THz pulses. When pumping with THz pulses
tuned just above the SC gap, we find the absorbed energy density required to
deplete superconductivity, $A_{dep}$, matches the thermodynamic condensation
energy. Contrary, by NIR pumping $A_{dep}$ is an order of magnitude higher,
despite the fact that the SC gap is much smaller than the energy of relevant
bosonic excitations. The result implies that only a small subset of bosons
contribute to pairing.
