Study On Characteristic Of Waveguide With Negative Refractive Index Material

After decades of development, the negative refractive index material has been used to make integrated optical devices from the original assumption and theoretical study, and one of the applications is the sensor with negative refractive index material. Comparison with the sensor with conventional material, the one with negative refractive index material have higher sensitivity and lower detection limits.The paper investigates the mode characteristics for the four-layer slab waveguide through Maxwell equations, by using numerical calculation method, and investigates the influence of negative refractive index layer on the waveguide model. the main contents and conclusions are detailed as follows:(1) the mode characteristics of a three-layer slab waveguide is introduced, and a buffer layer of negative refractive index is sandwiched between a semi-infinite cladding and the guiding layer, the mode equation and electric fields of linear slab waveguide of a four-layer slab waveguide in TE and TM modes are derived.(2) When the guiding layer with single negative refractive material, the influence of model parameters on the guiding mode and surface mode are investigated. The results show that the evanescent wave created at the boundary between the guiding layer and the buffer layer incites a surface guided mode at the boundary between the buffer layer and the cladding layer, and the evanescent wave in the cladding layer can be amplified by the buffer layer with negative refractive index material.(3) When the guiding layer with double negative refractive material, the influence of model parameters on the guiding mode is investigated. Through the analysis of the characteristic curve of the model, we can find that:the fundamental mode is exist in the proposed structure, mode-double-degeneracy appears for the high-order modes of TE mode and TM mode, and in the specific thickness of guided layer, the TE mode and TM mode in the same order have identical effective index. With the increase of buffer layer’s thickness and permittivity. With the increase of buffer layer’s thickness and permittivity, the mode-double-degeneracy of TM mode is more obvious. The transverse profiles are similar when the mode number m is odd or even, but as the thickness of guided layer increase, whose oscillating transverse profile in the waveguide is stronger, whereas the buffer layer is almost unchanged. We can flexibly convert mode characteristics of waveguide by control dielectric parameters of negative refractive index.