Si-based optical interconnect is an important approach to solve the bottleneck of Si integrated circuits due to its high speed, high bandwidth, low power consumption, and ability to be monolithically integrated on Si. Most of the key devices for Si-based optical interconnect have already been demonstrated, except Si-based light source. In Group IV, Ge has potential application in Si-based light emitting source via proper band engineering and other treatments because of its unique pseudo-direct bandgap structure. During the past years, Si-based emitting materials and light emitters obtained significant developments. We review and summarize the most recent progress in this field, including tensile strain Ge, Ge light emitting diode on Si, Ge laser on Si, and GeSn light emitting diode. Finally, the challenges and opportunities associated with these approaches are discussed.