We propose a unidirectional emission silicon/III-V laser, which comprises an III-V quantum wells microdisk connected to an output waveguide and a siliconon-insulator (SOI) waveguide. Characteristics of the III-V microdisk with an output waveguide and mode coupling between the III-V output waveguide and the SOI waveguide are investigated by three-dimensional (3D) finite-difference time-domain (FDTD) method. Simulation results show that the Q factor of a coupled mode for a 7.5 μm diameter microdisk connected to a 0.5 μm wide output waveguide is about 8.5
104. And the coupling efficiency between the III-V output waveguide and the SOI waveguide is over 96% when the III-V waveguide width is 0.5 μm, the SOI waveguide width is 0.565 μm and the vertical gap between those two waveguides is 0.1 μm. The proposed hybrid laser would be of valuable applications for on-chip interconnects.