An optical link may include a main optical waveguide; N sub-optical waveguides, where N is a natural number; N mode couplers, each configured to perform a mode coupling operation between the main optical waveguide and a respective one of the N sub-optical waveguide; and an optical wavelength filter connected to an output terminal of the main optical waveguide and an output terminal of each of the N sub-optical waveguides. A memory system may include a memory device, a memory controller, and the optical link. A data processing system may include the memory system and a central processing unit connected to the memory system through a bus.