The intersubband absorption saturation in GaAs/AlGaAs quantum wells as a function of the incident power has been measured, using picosecond micropulses with a power density up to 1 GW/cm2delivered by a free‐electron laser. The absorption in a sample with a bound‐to‐bound transition was compared to the absorption in a sample with a bound‐to‐resonant transition, and it was found that the electron relaxation time in the bound‐to‐bound transition is about four times shorter than for the bound‐to‐resonant transition. ©1995 American Institute of Physics.