Research On Topological Light Transport Of Valley Photonic Crystals In Integrated Photonics

In recent years,due to its high transmission speed,low energy consumption,information processing density and other advantages,silicon-based integrated optics is about to "fail" in the current integrated circuit Moore’s Law,and information science and technology urgently need to "surpass Moore" for "lane change overtaking" to stand out and get a lot of attention.As a micro-nano photonic structure that has been studied a lot recently,Valley Photonic Crystals belong to a kind of topological photonic crystals and have the characteristics of realizing the robust transmission of optical waves.Therefore,the combination of Valley Photonic Crystals and silicon-based integrated optics will hopefully solve the problem of reflection scattering during transmission that is difficult to solve in the current silicon-based integrated optical path.In this paper,for the silicon-based integrated optical platform based on Valley Photonic Crystals,we design and explore a variety of silicon-based photonic crystal optical processor devices,which promotes the path of silicon-based photonic crystal integrated optical path towards functional diversity.In view of the bandwidth problem of the unidirectional optical transport device of the Valley Photonic Crystal,we propose the triangular stomatal structure on the silicon substrate,which theoretically ensures the breaking of spatial inversion symmetry and the emergence of topological non-banality,and ensures that the device operates in a larger band gap.Finally,we achieved unidirectional topological optical transmission in the optical communication band,obtaining an operating bandwidth of about 230 nm near 1550 nm,of which the unidirectional operating bandwidth was as high as 217 nm and the robust transmission bandwidth was 178 nm.In addition,our theoretical research on increasing bandwidth also provides new ideas for the subsequent design of broadband Valley Photonic Crystal devices.Aiming at the problem of tunable edge state of Valley Photonic Crystals,we propose a method of modulating the stomata size at the topological boundary and then changing the relative refractive index at the boundary,and finally using the modulation to the marginal state frequency range.This method can change the operating bandwidth of silicon-based Valley Photonic Crystal devices without any additional conditions.Through this method,we designed a silicon-based Valley Photonic Crystal wavelength division multiplexing device in the optical communication band,which realizes two-way wavelength division multiplexing(1470 nm-1523 nm band and 1548 nm-1609 nm band),and achieves a contrast ratio of up to 22.7 d B and 24.9 d B in the two bands,which improves the low contrast of the traditional photonic crystal wavelength division multiplexing structure.Among them,our edge modulation method also provides a solution for the on-demand design of silicon-based Valley Photonic Crystal devices operating in the band.In view of the problem of interlayer optical transport of Valley Photonic Crystals,we designed the layer polarization type and layer mixed double layer Valley Photonic Crystals by layering,so as to introduce the interlayer degree of freedom into the valley photonic crystals.By analyzing the band structure and edge state structure of two kinds of bilayer Valley Photonic Crystals,the interlayer topology number is further defined to distinguish the double-layer Valley Photonic Crystals.Finally,through the numerical simulation of interlayer transmission,we obtain the "interlayer directional coupler" characteristic of the layer polarized double-layer Valley Photonic Crystal,which establishes the research basis for the prototype design of the "interlayer connector" by using the integrated optical platform of the Valley Photonic Crystal to achieve multi-dimensional light transmission.