A memory system includes a memory controller, a plurality of memory modules, and a memory bus connecting the memory controller and the plurality of memory modules. The memory bus includes at least one polarization-controlled optical channel configured to control a polarization of transmission light in response to a plurality of selection signals in order to transfer the transmission light to a target memory module among the plurality of memory modules. The transmission light is linearly-polarized light provided from the memory controller, and the plurality of selection signals correspond to the plurality of memory modules, respectively.