Wavelength-division multiplexing device and communications device

A wavelength-division multiplexing device comprising:

• a fastener, optical fibers, a filter, and a lens, wherein:
• the fastener is provided with an optical fiber positioning hole and a filter mounting groove, the filter mounting groove is disposed on a side of a tail end of the optical fiber positioning hole and that is away from an opening of the optical fiber positioning hole, and the filter mounting groove and the tail end of the optical fiber positioning hole are spaced apart;
• an optical fiber of the optical fibers is installed in the optical fiber positioning hole, the filter is installed in the filter mounting groove, and the filter is configured to transmit or reflect light rays emitted by the optical fiber;
• the lens is disposed between the optical fiber and the filter, and the lens is configured to:
• perform collimation processing on light rays emitted by the optical fiber, or
• converge collimated light rays and then input the converged light rays into the optical fiber;
• and
• a positioning step is disposed at the tail end of the optical fiber positioning hole, and the optical fiber is configured to abut against the positioning step.