Non-equilibrium condition N_2 > N_1 between an upper and lower level of a quantum system. Required for net stimulated emission (gain) at the corresponding transition. Achieved by pumping (optical, electrical, chemical) faster than…
Non-equilibrium condition N_2 > N_1 between an upper and lower level of a quantum system. Required for net stimulated emission (gain) at the corresponding transition. Achieved by pumping (optical, electrical, chemical) faster than…