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

In this letter, we have experimentally characterized the self-phase-modulat ion-induced spectral broadening of continuous-wave amplified spontaneous em ission (ASE) propagating in dispersion-shifted fiber samples. Experimental results for polarized and unpolarized beams show a dependence of the Kerr e ffect on the second-order degree of coherence of light g(11)((2)) (0). In p articular, the difference in second-order statistics for laser and ASE ligh t must be properly accounted for when estimating the Kerr effect for a reli able modeling of transmission in long-haul amplified optical links. Wheneve r the g(11)((2)) (0) = 2 value for ASE light cannot be properly reproduced in simulated transmission, an enhanced value for the Kerr coefficient n(2) with respect to the coherent light case, must be used in computing the effe cts of self-phase modulation for the ASE portion of light.