Angular Momentum Transfer between Quantum Oscillators

The transfer of angular momentum of light to a quasi-isotropic laser is theoretically and experimentally investigated. It is shown that the dynamics of the injected laser is governed not only by energy transfer but also by the conservation of angular momentum. In particular, the frequencies of the two angular momentum components of laser light must be described by two coupled equations which incorporate a light-induced Faraday effect. These quantum features of laser oscillators are taken into account in a simple model which is in good agreement with experiments.