Semiconductor optical amplifier and preparation method thereof

The embodiment of the invention provides a semiconductor optical amplifier and a preparation method thereof.The semiconductor optical amplifier comprises a waveguide structure, the waveguide structure is in a U shape, the two ends of the U shape of the waveguide structure serve as the input end and the output end of the semiconductor optical amplifier respectively, and the input end and the output end are both located on the optical coating face of the semiconductor optical amplifier; and the waveguide structure is inclined relative to the optical coating surface. Therefore, the input end and the output end are arranged on the same end face (an optical coating face) of the semiconductor optical amplifier by utilizing the U-shaped waveguide structure, so that an optical film only needs to be coated once in the technological process, the technological steps are reduced, and the technological process is optimized. In addition, an inclined waveguide structure is adopted, so that resonance of light waves in the se