Abstract: A device includes an integrated structure of an input fiber, a first output fiber, an input splitting/combining device, a first output splitting/combining device, an input rotation device, a first output rotation device, a first lens, an isolator core, a second lens, a second output rotation device, a second output splitting/combining device, and a second output fiber. With the integrated structure, the device integrates functions of an optical isolator and an optical splitter. As an optical splitter, input of an optical signal into the input fiber are distributed to the two output fibers for output. As an optical splitter, the device can isolate light in opposite directions and can reduce damage to a light source at the input. In a system, the device can replace two conventional optical isolators and optical splitters and effectively reduce space, simplify the assembly process, and facilitate miniaturization and integration for systems.