Path average measurements of optical fiber nonlinearity using solitons

This paper experimentally demonstrates a new method to determine the optical nonlinearity of single-mode optical fiber. The technique takes advantage of the well-known nonlinear response of optical fibers and well-developed models for soliton pulse propagation to extract information about the fiber characteristics. Fiber nonlinearity can degrade the performance of communication systems by, for example, causing crosstalk and signal distortions. Measuring the fiber nonlinearity would greatly aid system designers in building and upgrading communication systems. The method is utilized to determine values for n/sub 2//A/sub eff/, where n/sub 2/ is the nonlinearity of the glass and A/sub eff/ is effective area of the core. On various lengths of Corning SMF-28 fiber and Corning SMF-DS fiber. Experimentally measured propagation results for short (/spl ap/2 ps) optical pulses are compared to computer simulated models to determine the fiber nonlinearity. The method finds n/sub 2//A/sub eff/=3.0/spl times/10/sup -10/ W/sup -1/ values for short lengths (/spl ap/400 m) of Corning SMF-28 fiber and values of 2.7/spl times/10/sup -10/ W/sup -1/ for longer lengths (/spl ap/6.5 km and /spl ap/20 km). The difference is expected due to the 8/9 polarization scrambling factor, and the values are in agreement with reported literature [1]. The method also determines n/sub 2//A/sub eff/=5.6/spl times/10/sup -10/ W/sup -1/ for a /spl ap/12 km Corning dispersion shifted fiber. The method has two major regimes of operation based on the soliton period, a characteristic length for solitons. For few soliton periods (Z/Z/sub 0/ /spl sim/4) the output pulsewidth is measured as a function of launched power. The method's major advantage is its capability to measure long lengths of standard fiber, where it uses only standard diagnostic tools such as autocorrelation and optical power measurements. However, the method is only applicable in the soliton regime of fibers.