Research Of Double Electromagnetically Induced Transparency Mechanish Based On Dielectric Grating Waveguide System

Electromagnetically induced transparency(EIT)is a quantum interference phenomenon that occurs between different transition paths in an atomic three-level system.However,researchers turn to classical optical systems to simulate the EIT effect due to the harsh implementation conditions,which is also known as the EIT-like effect.At present,EIT-like effects have been achieved in waveguide-cavity systems,metamaterial systems,photonic crystals,and guided-mode resonance(GMR)systems.In metamaterials or waveguide-cavity systems,researchers have extended EIT to double transparent windows and even multiple transparent windows.However,the study of using guided-mode resonance effect to extend EIT to two transparent windows in dielectric grating waveguide systems has not been reported.This paper uses the finite difference time domain method(FDTD)to study the double EIT effect in a dielectric grating waveguide system.In this paper,we use FDTD numerical simulation to achieve the double EIT effect in two different dielectric grating waveguide systems,and use two different multi-level system models for theoretical explanation.The following are the main research contents and innovations of this article.1.We designed a double-bars dielectric grating waveguide system and realized the double EIT effect by using the GMR effect,the double-?five level atomic system is used to explain the double EIT mechanism.Two different transparent windows appeared in two different resonance dips caused by guided-mode resonance.And the quality factor(Q)of the two transparent windows is as high as 10~4,and two peaks transmittance are above 94%.The response wavelengths of the two EITs can be flexibly adjusted by changing different structural parameters.The two optical resolution FOM(figure of merit)of the dual-mode refractive index sensor designed based on this system reached 571.88and 587.42 respectively.2.We designed a waveguide system with a grating cascade structure,and once again realized the double EIT effect by using the GMR effect,the quasi-?four level atomic system is used to explain the double EIT mechanism.The double transparent windows appeared in the same resonance dip caused by the GMR effect.The work obtains the remarkable two optical delay times of 22.59 ps and8.43 ps.In addition,a broadband flat-top transparent window is realized by appropriately adjusting the response wavelength detuning between different guided modes.The researches not only are helpful to deeply understand the mechanism of the EIT effect in the dielectric grating waveguide system,but also obtain two methods to realize the double EIT effect and develop the related application of EIT.These research results have certain reference significance for the research and application of optical communication,integrated optical circuit and photoelectric information.