Double clad fiber coupler and device

摘要

There is described a double-clad fiber coupler (DCFC) composed of two double-clad fibers that have been fused together and tapered. The DCFC allows the propagation of light in the fundamental mode in its single-mode core with very little loss. Back reflected light may be collected two ways: by the core of the double-clad fiber and by the inner cladding of the double-clad fiber.

主权项

1. A double-clad fiber coupler comprising:
a first double-clad fiber having a first end, a second end, and a first middle portion therebetween, and having a first core, a first inner cladding, and a first outer cladding; a second double-clad fiber having a third end, a fourth end, and a second middle portion therebetween and having a second core, a second inner cladding, and a second outer cladding; and a fused region composed of the first middle portion fused to the second middle portion, wherein the first core and the second core remain separate and the first inner cladding and the second inner cladding are coupled to form a fused inner cladding, the fused region comprising a first diameter transition section, a constant diameter section, and a second diameter transition section, the first diameter transition section corresponding to a down-taper of the fused region and the second diameter transition section corresponding to an up-taper of the fused region, the fused region section having a predetermined taper ratio, and wherein the fused region allows light injected in the first core at the first end to be transmitted in the first core to the second end, light injected in the first core at the second end is transmitted in the first core to the first end, and light injected in the first inner cladding at the second end is substantially equally split between the first inner cladding towards the first end and the second inner cladding towards the third end;wherein the predetermined taper ratio is comprised between about 0.1 and about 0.6.