Patent ID: 10931075

Abstract:
Apparatus for optical isolation, which apparatus comprises a laser (1), a beam delivery system (91), and an output port (92), wherein: the beam delivery system (91) comprises an optical isolator (8) and an optical fibre (2); the laser (1) is defined by a peak power (21); the laser (1) emits laser radiation (13) at a signal wavelength (19); the laser radiation (13) is coupled from the laser (1) to the output port (92) via the beam delivery system (91); and the optical fibre (2) comprises an optical waveguide (100) defined by a core (101), a cladding (102), a mode field area (104) at the signal wavelength (19), a length (86), and a Raman wavelength (25); and the apparatus being characterised in that: the Raman wavelength (25) is longer than the signal wavelength (19); the beam delivery system (91) attenuates the laser radiation (13) at the signal wavelength (19) such that the power of the laser radiation (13) emitted by the laser (1) is more than the power of the laser radiation (13) at the output port (92); the apparatus does not include a pump for pumping the laser radiation (13) at the signal wavelength (19) as the laser radiation (13) propagates along the optical fibre (2); the optical isolator (8) has greater backward optical isolation (33) and greater forward transmission (28) at the signal wavelength (19) compared to the Raman wavelength (25); and the optical fibre (2) comprises a suppressing means (94) for suppressing stimulated Raman scattering.