Online optical isolator

The embodiment of the invention discloses an online optical isolator. The optical isolator sequentially comprises an optical fiber output module, a collimation output module, an input coupling module and an optical fiber coupling module along an optical path direction, the optical isolator further comprises a light beam isolation module, and the light beam isolation module comprises at least one single-stage light beam isolation module. The single-stage light beam isolation module is arranged between the optical fiber output module and the collimation output module, and/or between the input coupling module and the optical fiber coupling module; the single-stage light beam isolation module comprises a magnetic tube, and a light splitting crystal, a wave plate, a Faraday rotation sheet and a light combining crystal which are arranged in the magnetic tube in sequence along the light path direction. According to the optical isolator, various single-stage and multi-stage on-line optical isolators can be freely com