UV trimming of fused fiber coupler spectral response: a complete model

In this letter, we propose a complete model of the transmission change of fused tapered fiber couplers exposed to uniform UV light by using supermode propagation theory. The main contribution of this change is found to be a decrease of the supermode propagation constant difference. This effect is found to be more significant when supermodes become cladding modes. The model shows a good qualitative agreement with experimental results found in the literature.