Amplification in Nonlinear Reactive Networks

Sufficient conditions for validity of the Manley-Rowe equations in a classical nonlinear reactive network are shown to be conservation of energy and proportionality of average power with frequency. It is shown by counter example that conservation of energy alone is insufficient. A sufficient condition for a quantum mechanical maser model is found to be equilibrium of state populations. In this case conservation of energy follows as a consequence from the equilibrium condition, but proportionality of power with frequency is not required.