We show that, although the efficiency of a multiwave mixing process can be significantly enhanced by an ultra-slowly-propagating pump wave, a three-photon destructive interference between the generated wave and the pump wave limits the final achievable conversion efficiency.
We propose a dual electromagnetically induced transparency (EIT) based multiwave mixing scheme that retains the significantly enhanced conversion efficiency enabled by ultraslow propagation of pump waves, yet is also capable of inhibiting and delaying the onset of the detrimental three-photon destructive interference that limits the further growth of the four-wave mixing (FWM) field. We show that the new scheme exhibits a wave-matching condition that is fundamentally different from the conventional FWM without EIT, and the efficient generation of the mixing wave is not critically dependent upon the FWM detuning to achieve constructive interference as required in the conventional FWM. These are significant steps forward in enabling applications of ultraslow wave nonlinear optics.
We analyze a lifetime-broadened four-state four-wave-mixing (FWM) scheme in the ultraslow propagation regime and show that the generated FWM field can acquire the same group velocity and pulse shape as those of an ultraslow pump field. We show that a new type of induced transparency resulted from multiphoton destructive interference that significantly reduced the pump field loss. Such induced transparency based on multphoton destructive interference may have important applications in other nonlinear optical processes.
We show that by strongly modifying the dispersion properties of a four-level system, non-existing wave mixing channels can be opened and significantly enhanced. Specifically, we show that coherent optical four-wave mixing with a pump wave mediated by electromagnetically induced transparency (thereby propagating with an extremely slow group velocity) will lead to many orders of magnitude enhancement in the amplitude of the generated wave. Contrary to common belief, a large transparency window, which causes a large propagation velocity, actually diminishes efficient mixing wave production.