A unified classical stochastic treatment of spontaneous and stimulated emission in a free-electron-laser oscillator is presented. The theory accounts for photon noise phenomenologically and includes also the effects of electron shot noise. Computer simulation results for the time evolution of the laser field, from incoherent spontaneous emission to coherent stimulated emission and eventual saturation, are reported for a one-dimensional model of the Stanford free-electron-laser oscillator.
A. T. Georges, A. T. Georges,
"From Noise To Coherence In A Free-Electron Laser Oscillator", Proc. SPIE 0453, Free-Electron Generators of Coherent Radiation, (16 February 1984); doi: 10.1117/12.947111; https://doi.org/10.1117/12.947111