Measurements of n/sub 2/ and normalization factor for random polarization in optical fibers

We measure the nonlinear coefficient through the effect of self-phase modulation (SPM) and cross-polarization (XPM) on a cw dual-frequency beat signal. Firstly, the nonlinear refractive index n/sub 2/ for collinear polarization was measured through SPM. The copolarized output from two equal intensity DFB laser diodes centered at 1548.5 nm with a wavelength separation of 0.3 nm were used to generate a beat signal. This was amplified in an EDFA and on propagating through a dispersion-shifted fiber (DSF) of length 1-5 km experienced SPM.