A fiber isolator made using the Faradayrotation effect consists of a central CORE, and two fiber collimators at bothends. The CORE is composed of a Faraday crystal plate, two crystal wedges and amagnetic tube on the periphery. As needed, the CORE can be designed for differentworking wavelengths. If isolation of the single-stage CORE is insufficient, atwo-stage CORE can also be made.