| 摘要 |
<p>A method for creating population inversions for use in stimulated emission devices which beam combine, beam clean-up, or frequency up-convert electromagnetic radiation. The invention comprises near resonantly enhanced multiphoton pumping of a multi-level quantum medium with pump beams of appropriate intensities and frequencies detuned from the transition frequencies of the medium. The intensities are orders of magnitude lower than those required for non-resonantly enhanced multiphoton pumping. The detuning is smaller for the maximum multiphoton resonance than for the single photon resonances. Appropriate medium decay constants are required for creating a population inversion between energy levels of the quantum medium. The population inversion exists between energy levels of the medium whose energy difference may exceed the energy of any single pump photon energy. The appropriate energies, detunings, intensities, and decay constants are determined by analysis of the semiclassical densities matrix equations for the multi-level quantum medium. The energy extracted from the population inversion may be at a frequency nearly equal to or greater than the pump frequencies.</p> |
