Active Control Of Electromagnetically Induced Transparency Analogue In Coupled Cavity-waveguide Systems Integrated With Black Phosphorus

Electromagnetically Induced Transparency(EIT)is the result of quantum destructive interference in the three-level atomic system.The absorption and dispersion characteristics have changed drastically in the transparent window which has potential applications in slow light,optical storage and other nonlinear optical processes.Many researchers have proposed some solutions similar to the EIT(EIT-like)effect by designing coherent excitation paths in various model systems(including photonic crystal waveguides,optomechanical systems,coupled optical resonators,and metamaterials).EIT-like effects have been observed in various types of resonator systems.But EIT-like effects based on one-dimensional photonic crystal nanobeam cavities are rarely reported in the literature.In addition,it is very important in practical applications that effective control of dispersion and group delay and active modulation of EITlike.The most commonly method is to integrate tunable materials to achieve adjustable transparent windows.Black phosphorus is an emerging two-dimensional material and there is an order of magnitude difference between the effective electron mass in the armchair lattice direction(x direction)and the zigzag lattice direction(y direction)which leads to anisotropic electrical and optical properties.Black phosphorus has huge application potential in the fields of photoelectric sensing,imaging,micro-nano devices,and photodetectors.The main research contents of this paper are as follows:1.We proposed a new photonic crystal nanobeam cavity-waveguide coupling system,which consists of a strip waveguide and two one-dimensional photonic crystal nanobeam cavities and one of the surface of the microcavities is covered with black phosphorus,which can achieve the unique EIT-like effect.The transmission characteristics and EIT-like effects of the system are studied using the finite difference time domain method.And the numerical simulation results show that the active control of the transparent window in the EIT-like effect can be achieved by changing the distance between the two microcavities.In addition,it can also realize the active regulation of the transparent window in the EIT-like effect when the coupling distance between the two microcavities is fixed by adjusting the Fermi level of black phosphorus2.We conducted a theoretical analysis based on the coupled mode theory and explored its potential physical mechanism which are highly consistent with the numerical results.Theoretical analysis shows that the active modulation of the EIT-like effect is due to the change of the dark mode cavity loss results.In addition,the group delay of the accompanying EIT-like system is calculated.The results show that when the black phosphorus takes the armchair lattice orientation,the maximum group delay of the system is 2.9 ps.When the black phosphorus takes the zigzag lattice direction,the maximum group delay of the system is 4.5 ps.At the same time,the group delay can also be actively controlled by changing the Fermi level of black phosphorus.