Clad mode stripper

摘要

A clad mode stripper is provided on a passive double-clad fiber guiding amplified light signal downstream from a gain block. The fiber is configured with an upstream end stripped from a protective coating. A light absorbing mixture is applied to the exposed cladding of the fiber receiving unwanted pump light. The mixture includes a host material and a plurality of diffusers which are operative to scatter cladding light incident thereon and embedded in the host material so as to define upstream and downstream decoupling zones. The diffusers are selected from either silicone polymers with a refractive index lower than that of the host material or from metal particles and lower the effective refractive index of the mixture so that it at most equal to that of the cladding. The mixture is operative to gradually remove substantially entire unwanted light guided by the cladding so that the downstream decoupling zone is heated at a temperature lower than that of the upstream zone.

主权项

1. A device for gradually removing cladding modes during a switch-on operational phase of high power single mode fiber laser system, comprising:
a double-clad fiber including a core and a cladding surrounding the core; a light absorber being in direct contact with a portion of the cladding and including a mixture of host material and plurality of passive light diffusers, which are embedded in the host material to provide the mixture with an effective refractive index at most equal to a refractive index of the cladding, the passive diffusers scattering clad light incident thereupon along an entire length of the absorber so that an upstream zone of the absorber heats at a temperature lower than that of at least one downstream zone, wherein the clad light is substantially removed from the cladding at an end of the switch-on phase.