Optically induced diffraction gratings based on periodic modulation of linear and nonlinear effects for atom-light coupling quantum systems near plasmonic nanostructures

Azar Vafafard,Hamid Reza Hamedi,Vahid Siahpoush,Seyyed Hossein Asadpour,Mostafa Sahrai

doi:10.1038/s41598-020-73587-y

Abstract

We investigate the quantum linear and nonlinear effects in a novel five-level quantum system placed near a plasmonic nanostructure. Such a quantum scheme contains a double-V-type subsystem interacting with a weak probe field. The double-V-subsystem is then coupled to an excited state by a strong coupling field, which can be a position-dependent standing-wave field. We start by analyzing the first-order linear as well as the third and fifth order nonlinear terms of the probe susceptibility by systematically solving the equations for the matter-fields. When the quantum system is near the plasmonic nanostructure, the coherent control of linear and nonlinear susceptibilities becomes inevitable, leading to vanishing absorption effects and enhancing the nonlinearities. We also show that when the coupling light involves a standing-wave pattern, the periodic modulation of linear and nonlinear spectra results in an efficient scheme for the electromagnetically induced grating (EIG). In particular, the diffraction efficiency is influenced by changing the distance between the quantum system and plasmonic nanostructure. The proposed scheme may find potential applications in future nanoscale photonic devices.

Highlights

We investigate the quantum linear and nonlinear effects in a novel five-level quantum system placed near a plasmonic nanostructure
The current study extends the previous works to a five-level quantum system near plasmonic nanostructure through coherently adjusting nonlinear parts of susceptibility
We investigate the linear and nonlinear properties of the quantum system placed near the plasmonic nanostructure when α = 1 and β = −1 and for different distances between the quantum system and plasmonic nanostructure

Summary

Theoretical model and formulation

According to Eq (11d), the cross-Kerr nonlinearity increases when the coupling field is out of the resonance condition with the corresponding transition Such an enhancement may be accompanied by vanishing linear absorption via adjusting the distance from the plasmonic nanostructure. We are moving to the regime where a considerable portion of energy is transferred from zero-order to first-order of diffraction direction with a high efficiency This is the distance from the surface of plasmonic nanostructure for which we observed an enhanced cross- Kerr nonlinear with vanishing absorption effects

Conclusion

Additional information