Measurement of n/sub 2/ of various types of fibres used for ultra-high bit rate transmission

A reliable and simple method for measuring n/sub 2//A/sub e/ff is described This technique has the advantage of making use of CW lasers only and, therefore, the power measurements become considerably more accurate than when pulses are employed. Also, the fact that equal intensity spectral lines are used represents a great simplification of the calculations involved in determining the maximum nonlinear phase shift. The value of n/sub 2//A/sub e/ff was measured for several fibres with different compositions, namely, single mode fibres (SMF), five dispersion shifted fibres (DSF) and eight dispersion compensating fibres (DCF), four with Ge-doping only and four with Ge and F-doping. The error in the values obtained was never greater than 10% and agreed well with the fibre's dopants concentrations and profile.