Measurement of self-phase modulation of amplified spontaneous emission: the role of second-order degree of coherence in determining the Kerr effect

We have experimentally characterized the self-phase-modulation-induced spectral broadening of continuous-wave amplified spontaneous emission (ASE) propagating in dispersion-shifted fiber samples. Experimental results for polarized and unpolarized beams show a dependence of the Kerr effect on the second-order degree of coherence of light g/sub 11//sup (2)/(0). In particular, the difference in second-order statistics for laser and ASE light must be properly accounted for when estimating the Kerr effect for a reliable modeling of transmission in long-haul amplified optical links. Whenever the g/sub 11//sup (2)/(0)=2 value for ASE light cannot be properly reproduced in simulated transmission, an enhanced value for the Kerr coefficient n/sub 2/ with respect to the coherent light case, must be used in computing the effects of self-phase modulation for the ASE portion of light.