This paper discusses the process of triggering photon avalanche in deep doped quantum wells. The threshold intensities of the IR light that causes the avalanche are hundreds of kilowatts per square centimeter. The energies for switching the system between states with strong and weak absorption of the pump light are tens of femtojoules per square micrometer.
E. Yu. Perlin and R. S. Levitskii, "Photon avalanche in doped quantum wells: Up-conversion and the switching effect," J. Opt. Technol. 73, 1-8 (2006)