The effect of an axial dip and ripples in the inner cladding on the leakage loss of LP01 mode in depressed index clad fibre

The effect of profile imperfections, like axial index dip and layered structure in the inner cladding, on the leakage loss of LP₀₁ mode in MCVD made single-mode depressed index cladding (DIC) fibres is investigated quantitatively through a matrix approach. The study reveals that these apparent profile imperfections may greatly affect leakage loss coefficients especially at longer wavelengths. A typical example of the presence of a linear axial dip along with ripples in the inner cladding is seen to increase the leakage loss coefficient of the LP₀₁ mode to 43.44 dB/km from a value of 0.25 dB/km at 1.3 μm in the absence of profile perturbation