Adiabatic elimination in waveguides for broadband light transfer

Fu-Quan Dou, Zhi-Ming Yan, Xuan-Qing Liu +2 more

Andon A. Rangelov, U. Gaubatz, Nikolay V. Vitanov

Germano Montemezzani, Virginie Coda, Charles Ciret +2 more

Hassan Oukraou, Virginie Coda, Andon A. Rangelov +1 more

We propose an adiabatic method for the robust transfer of light between the two outer waveguides in a three-waveguide directional coupler. Unlike the established technique inherited from stimulated Raman adiabatic passage (STIRAP), the method proposed here is symmetric with respect to an exchange of the left and right waveguides in the structure and permits the transfer in both directions. The technique uses the adiabatic elimination of the middle waveguide together with level crossing and adiabatic passage in an effective two-state system involving only the external waveguides. It requires a strong detuning between the outer and the middle waveguide and does not rely on the adiabatic transfer state (dark state) underlying the STIRAP process. The suggested technique is generalized to an array of $N$ waveguides and verified by numerical beam propagation calculations.

Xin-Ding Zhang, Wenjie Liu, Guang-Fei Yang

Rim Alrifai, Virginie Coda, Toni Alhaddad +3 more

We propose a method for robust mode conversion between the two outer waveguides in a three-waveguide coupler based on analogies with quantum population transfer. Depending on the presence or absence of detuning between the propagation constants of the intermediate waveguide, the mode conversion can be analogous to the adiabatic-elimination or stimulated Raman adiabatic passage techniques. Both configurations give broadband and robust mode converters.