Ta2O5 based nonlinear waveguide for Si photonics
演讲课题：Ta2O5 based nonlinear waveguide for Si photonics
To achieve high bit rate signal processing in the integrated optical system, the ultrafast all optical modulator is regarded as the key element in the modern optical communication system. Up to date, number of material systems, such as Si, SiO, SiN and so on, have been chosen for nonlinear optical processing in waveguide photonics fields. However, the physical limitation on application is on the inevitable linear or nonlinear absorption performance. For example, Si has only a finite transparency range, restricting its usage in the visible region. Furthermore, Si suffers from significant two-photon as well as free-carrier absorption due to low band gap structure, greatly suppressing the nonlinear optical property, and hence the nonlinear optical application in Si photonics. On the other hand, low nonlinear coefficient in SiO2 and high stress on depositing thick Si3N4 film has posed material limitation on applications. As a result, seeking high-nonlinearity material while maintaining low absorption is always an important issue to enable all-optical photonics. Recently, a low-loss and high-Q Ta2O5 based micro-ring resonator is developed and presented. The micro-ring resonator and channel waveguide with core area of the 700 by 400 nm2 were fabricated on amorphous Ta2O5 thin films prepared by reactive sputtering with Q as high as 2x105. Meanwhile, the nonlinear refractive index of Ta2O5 waveguide at 1550 nm as high as 4 × 10−14 cm2∕W was also reported. In this work, the progress of nonlinear optical properties of low loss waveguide based on Tantalum Pentoxide (Ta2O5) will be introduced. In addition, the application for Si photonics will be discussed as well.