Formation and annihilation of laser light pulse quanta in   thermodynamic-like pathway
  We present a theoretical and experimental study of multiple pulse formation in passively mode-locked (PML) lasers. Following a statistical mechanics approach, the study yields a thermodynamic-like "phase diagram" with boundaries representing cascaded first order phase transitions. They correspond to abrupt creation or annihilation of pulses and a quantized RF power behavior, as system parameters (noise and/or pumping levels) are varied, in excellent accordance with the experiments. Remarkably, individual pulses carry an almost constant quantum of energy. 
Boris Vodonos, Rafi Weill, Ariel Gordon, Alexander Bekker, Vladimir   Smulakovsky, Omri Gat and Baruch Fischer