Effective hamiltonians in two-photon laser theory

Ning Lü, Shi-Yao Zhu

Jakub Zakrzewski, Maciej Lewenstein, THOMAS W. MOSSBERG

We present a detailed theory of dressed-state lasers, i.e., the lasers that operate due to the gain on an inverted transition between dressed states of a coupled atom-field system. We derive effective Hamiltonians that describe such lasers for the case of one- and two-photon resonances. We argue that, due to the presence of nearly resonant intermediate states, the use of gain media consisting of strongly driven two-level atoms provides an unorthodox yet promising means for achieving cw optical two-photon laser oscillation. We disscuss the stability properties of radiation generated by such media.

Wang Zhi Cheng, Hermann Haken

Wang Zhicheng, 兰州大学物理系,兰州,730001

Starting from the microscopic Hamiltonian of the three-level model and making use of the slowly varying amplitude approximation and the two-photon rotating wave approximation, we derive an effective Hamiltonian for the two-level two photon model under conditions where the two-photon process dominates the other radiartive processes, so that an exact relation between the three-level model and the two-level two-photon model is established. The effective Hamiltonian includes a term come from the optical Stark effect which was neglected in the conventional treatment. The coefficient of this term may have the same order of magnitude as the effective coupling constant. Based on this effective Hamiltonian, the standard method of Haken's laser theory is applied to study the threshold, the mean photon number, the self-induced frequency shift, the photon statistics and the fluctuation in steady states. Results are compared with previous ones which neglect the Strk effect.

Z. C. Wang, Hermann Haken

Z. C. Wang, Hermann Haken