A housing for packaging an optical transmitter module, wherein the housing comprises a body, a focusing structure, a first bent three-dimensional, 3D, optical waveguide, and an optical fiber interface, the optical fiber interface is configured to accommodate a single-mode optical fiber, and the first 3D optical waveguide is embedded in the body; the focusing structure is configured to: receive a first single-mode optical signal transmitted by a single-mode laser, and enable the received first single-mode optical signal to be focused for a first time at a focal point of the focusing structure; and the first 3D optical waveguide is configured to: receive, from an input end of the first 3D optical waveguide, the first single-mode optical signal that has been focused for the first time, and output, from an output end of the first 3D optical waveguide, the first single-mode optical signal that has been focused for the first time to the single-mode optical fiber, wherein the focal point of the focusing structure coincides with the input end of the first 3D optical waveguide, wherein the first 3D optical waveguide comprises an input portion and a transmission portion, an input end of the input portion is the input end of the first 3D optical waveguide, and an output end of the transmission portion is the output end of the first 3D optical waveguide; the input portion is configured to: receive, from the input end of the input portion, the first single-mode optical signal that has been focused for the first time, and transmit the first single-mode optical signal that has been focused for the first time to the transmission portion; the transmission portion is configured to: receive the first single-mode optical signal that has been focused for the first time, and output, from the output end of the transmission portion, the first single-mode optical signal that has been focused for the first time to the single-mode optical fiber; characterized in that the optical fiber interface is located inside the body and a diameter of the input portion decreases evenly in a transmission direction of an optical signal in the input portion, and a minimum diameter of the input portion is the same as a diameter of the transmission portion, wherein the input portion and the transmission portion are two independent subwaveguides, the input portion is a first subwaveguide, and the transmission portion is a second subwaveguide, the housing further comprises a second reflective surface, wherein the second reflective surface is located inside the body, and an output end of the first subwaveguide and an input end of the second subwaveguide are both in contact with the second reflective surface; and the second reflective surface is configured to: receive the first single-mode optical signal that has been focused for the first time and that is transmitted by the first subwaveguide, and transmit the first single-mode optical signal that has been focused for the first time to the second subwaveguide. the focusing structure is configured to: receive a first single-mode optical signal transmitted by a single-mode laser, and enable the received first single-mode optical signal to be focused for a first time at a focal point of the focusing structure; and the first 3D optical waveguide is configured to: receive, from an input end of the first 3D optical waveguide, the first single-mode optical signal that has been focused for the first time, and output, from an output end of the first 3D optical waveguide, the first single-mode optical signal that has been focused for the first time to the single-mode optical fiber, wherein the focal point of the focusing structure coincides with the input end of the first 3D optical waveguide, wherein the first 3D optical waveguide comprises an input portion and a transmission portion, an input end of the input portion is the input end of the first 3D optical waveguide, and an output end of the transmission portion is the output end of the first 3D optical waveguide; the input portion is configured to: receive, from the input end of the input portion, the first single-mode optical signal that has been focused for the first time, and transmit the first single-mode optical signal that has been focused for the first time to the transmission portion; the transmission portion is configured to: receive the first single-mode optical signal that has been focused for the first time, and output, from the output end of the transmission portion, the first single-mode optical signal that has been focused for the first time to the single-mode optical fiber; characterized in that the optical fiber interface is located inside the body and a diameter of the input portion decreases evenly in a transmission direction of an optical signal in the input portion, and a minimum diameter of the input portion is the same as a diameter of the transmission portion, wherein the input portion and the transmission portion are two independent subwaveguides, the input portion is a first subwaveguide, and the transmission portion is a second subwaveguide, the housing further comprises a second reflective surface, wherein the second reflective surface is located inside the body, and an output end of the first subwaveguide and an input end of the second subwaveguide are both in contact with the second reflective surface; and the second reflective surface is configured to: receive the first single-mode optical signal that has been focused for the first time and that is transmitted by the first subwaveguide, and transmit the first single-mode optical signal that has been focused for the first time to the second subwaveguide.