Fibre-optic connector employing mode field modification.

摘要

Disclosed is a mode field modifier (40) for use with an optical fibre (54) having a core (56) and a cladding (58) of outside diameter d. The modifier comprises a modifier core (42) having a refractive index n1. Surrounding the modifier core is first cladding layer (44) having a refractive index n2 that is less than n1. On the surface of the first cladding layer is a second cladding layer (46) having a refractive index n3 which is less than n2. The modifier is tapered intermediate its ends whereby it has a large diameter end and a small diameter end. The diameters of at least the core and first cladding layer at the large diameter end are greater than the corresponding diameters at the small diameter end. The diameter D1 of the first cladding layer at the large diameter end is greater than d. An axially disposed hole (52) in the large diameter end receives a fiber (54) which is held in such alignment with the mode field modifier (40) that it is in light coupling relationship with the modifier core (42). The mode field of a signal coupled from the fiber to the mode field modifier expands as it propagates through the tapered portion of the modifier to the small diameter end. An in-line coupler between two optical fibers is effected by connecting together in axial alignment two such mode field modifiers with their small diameter ends adjacent one another.