Figure 1: AE scheme in atomic physics and optical waveguides.

A general three-coupled mode system can be realized in (a) atomic systems and in (b) three-waveguide coupler. These systems share equivalent dynamics where the time evolution of the population of electrons in each level is analogous to the electric field propagation in each waveguide. In both cases, the evolution is dictated by the couplings between the modes, V_ij and by the detunings Δ_ij or the difference between propagation constants Δβ_ij. (c) The intensity evolution in three identical waveguides, where V₁₂=V₂₃ and the light is injected in waveguide 1. This evolution is equivalent to on-resonant three-level atomic interactions, where all the electrons are initially in the ground state. As seen, all the waveguides have a significant light intensity throughout the propagation as a result of the couplings. (d) AE process in the atomic system relies on a strong coupling between nearby levels that exhibit a very large detuning between them (Δ₁₂, Δ₂₃≫V₁₂, V₂₃). Since each of the two coupling processes is greatly detuned, the amplitude of the intermediate level oscillates very rapidly in comparison to the slow varying population in the other levels resulting in no significant build up and remaining at its initial value. The three-level system is thus reduced to an effective two-level system with an effective coupling between the ground and the excited states, with the intermediate level being a ‘dark’ state. (e) AE analogue in optical waveguides. The outer waveguides become an effective two-mode coupler with and the middle waveguide is a ‘dark mode’. Importantly, the coupling between the two outer waveguides is now controllable through Δβ₁₂. (f) When AE conditions are met, the light injected in waveguide 1 propagates only in the outer waveguides 1 and 3. The middle waveguide is effectively eliminated, as its energy build-up remains very low during the entire propagation.