US Patent 10310201 Back-reflection protection and monitoring in fiber and fiber-delivered lasers

A system includes an optical fiber situated to propagate a laser beam received from a laser source to an output of the optical fiber, a first cladding light stripper optically coupled to the optical fiber and situated to extract at least a portion of forward-propagating cladding light in the optical fiber, and a second cladding light stripper optically coupled to the optical fiber between the first cladding light stripper and the optical fiber output and situated to extract at least a portion of backward-propagating cladding light in the optical fiber.