The progress of silicon-based grating couplers

Silicon-based photonic integrated chips recently have attracted great attention and actively intervened in many applications such as optical communications, optical interconnects, and optical sensing for relevant research institutions. Photonic integrated circuits are the key block to build information infrastructures. Among of them, grating couplers play an important role in silicon photonics, due to high efficient optical coupling on/off photonic chips. Also, they have many advantages in high density photonic packaging and on-wafer testing, such as large alignment tolerances and no requirements for wafer scribing or chip polishing. This review focuses on the principles and performances of grating couplers on silicon-on-insulator substrates. In this article, we also discuss the state-of-art and the trends in the near future, with a summary of our achievements over the last few years.