Research On Micro/Nano Photonic Devices Based On Inverse Design

With the development of photonic integrated circuits,photonic devices are gradually developing towards miniaturization and large-scale integration.The development of silicon photonics and the maturity of silicon on insulators process have created possibilities for large-scale optoelectronic integration.The method of inverse design is an important design theory,which is a typical application of machine learning in the area of designing micro/nano photonic devices.By taking the advantage of the high precision of etching process,the structure of the device can be automatically designed efficiently with high performance intelligent algorithms.Therefore,further research on the existing inverse design platform will be of great benefit to improve the integrated scale of photonic integrated circuits.Besides,with the growth of the scale and complexity of photonic integrated circuits,traditional single-layer silicon chips can hardly meet the integration requirements of large-scale micro/nano photonic devices.Considering the development of electronic integrated circuits,it is an inevitable trend to research and develop 3D photonic integrated circuits,which is of great significance to improve the integrated density of traditional 2D photonic integrated circuits.At the same time,with the development of surface plasmon polaritons effect and metasurface technology in recent years,metal materials are more and more widely used in the design of micro/nano photonic devices.So,it is necessary to introduce metal materials into the current inverse design platform,which will enrich the design functionalities of the inverse design platform and improve the design efficiency of the metasurface devices.In summary,this paper focuses on the 3D/multi-layer inverse design platform and the metal model of inverse design.The main contents and results of this paper are as follows:(1)Firstly,based on the traditional inverse design platform for 2D planar structure,we have constructed a multi-layer inverse design platform for designing multi-layer structure in 3D space and proposed a novel micro/nano photonic device namely vertical light via,which is the key device in the 3D photonic integrated circuits for interlayer connection.With the help of the multi-layer inverse design platform,we design a vertical light via with a small footprint of only 2.8?m×2.8 ?m.And the simulation results of the coupling efficiency and insertion loss are 88.18%and 0.55 dB respectfully@1550 nm,with a 1 dB operating bandwidth of approximately 260 nm.Besides,we have also analyzed the influence of initial parameters on the performance of the light via and further optimize its transmission efficiency.(2)Then,we proposed and design a polarization rotator with multi-layer structure by further taking the advantages of multi-layer inverse design platform.The device exhibits a good performance of high extinction ratio of 25 dB with a coupling length of only 2.8 ?m@1550 nm,while the insertion loss is slightly high as 3.29 dB.Besides,it has an effective operating bandwidth of 64 nm and achieves an extinction ratio as high as 46.48 dB @ 1516 nm.We have also analyzed the influence of initial parameters on performance of the polarization rotator and further optimize its insertion loss.(3)Finally,the metal model of inverse design is established and verified.By introducing surface plasmon polaritons effect and metasurface theory into the multi-layer inverse design platform,we designed two new types of polarization rotator.The polarization rotator based on surface plasmon polaritons effect can achieve a conversion efficiency up to 58.62%@1550 nm.Moreover,the introduction of metal material has obviously accelerated the inverse design process of polarization rotator and has a significant auxiliary effect on realizing the functionality of polarization rotation.Besides,we have also analyzed the influence of initial parameters on the performance of the polarization rotator and further optimize its conversion efficiency.