A housing for packaging an optical transmitter module includes a body, a focusing structure, a first three-dimensional (3D) optical waveguide, and an optical fiber interface. The optical fiber interface is located inside the body and configured to accommodate a single-mode optical fiber. The first 3D optical waveguide is embedded in the body. The focusing structure is configured to receive a first single-mode optical signal and enable the received first single-mode optical signal to be focused for a first time at a focal point of the focusing structure. The first 3D optical waveguide is configured to receive the first single-mode optical signal, and output the first single-mode optical signal to the single-mode optical fiber. The focal point of the focusing structure coincides with an input end of the first 3D optical waveguide.