With the increasing bandwidth requirement in computing and signal processing, the inherent limitations in metallic interconnection are seriously threatening the future of traditional IC industry. Silicon photonics can provide a low-cost approach to overcome the bottleneck of the high data rate transmission by replacing the original electronic integrated circuits with photonic integrated circuits. Although the commercial promise has not been realized, this perspective gives huge impetus to the development of silicon photonics these years. This paper provides an overview of the progress and the state of the art of each component in silicon photonics, including waveguides, filters, modulators, detectors, and lasers, mainly in the last five years.