Non-adiabatic losses in fused fiber couplers-experimental findings

Bi-conically tapered single-mode couplers are fabricated using a fiber fusion coupler workstation. Losses found during fabrication are analyzed for a range of elongation. It is found that longer elongations will lower the losses. Theoretically, the losses are due to the taper paths crossing delineating curves. These losses which occur during tapering process are not really adiabatic if part of the signal power is not guided at the end of tapering process. In other words, taper path will not be inside adiabatic region of cladding guidance. It will cross from core-guidance region into lossy region or non-adiabatic region of cladding guidance.