Chirp Of Soliton Under Some Transmission Conditions

According the NLS and ENLS equations, the chirp of soliton is studied when transmitting under some conditions by means of parse and numerical computing. The functions of GVD-caused chirp and SPM-caused chirp are calculated in calculus approximation. The evolution of second-order soliton's chirp is studied for the first time. Also is the chirp of soliton in dispersion-decreasing fiber (DDF) of types of dispersion profiles. How the chirp is affected by factors in polarization multiplexed communication system is studied in detail. Finally, The super short soliton's chirp caused by high order effects-TOD, SS (self steepening), and ISRS -is studied. Conclusions are as the followings:Fundamental soliton's chirp is always zero, which comes from the well offset between GVD-caused chirp and SPM-caused chirp. The evolution trend for chirp of high-order soliton is complicated. A case in point is the second-order soliton's chirp, which turns large and conversely at the half of soliton cycle length.In the DDF, the soliton's chirp differs in response to the dispersion profiles. The GVD-caused chirp in the exponential type of DDF is the least likely to be affected by the initial chirp. The GVD-caused chirp in exponential, linear, Logarithm and Gaussian types of DDF has similar synchronous character of saturation with the SPM-caused chirp, which makes the sum chirp tend to be zero. From this aspect, the type of Exponential is of the most practical value for soliton communications system, while linear and Gaussian types are the best two types for pulse compression.In polarization multiplexed communication system, soliton's sum-chirp is found to have the character of saturation caused by fiber attenuation. The Sum-chirp's value appears different between the two neighboring pulses according to their difference in the incidence amplitude. Sum-chirp is dominated by the initial chirp at short distances, and by nonlinear effects at long distances. It will be influenced by wavevector mismatch parameter below 1 Ops/km.Chirp caused by TOD, SS and ISRS make the super short soliton pulse deform and fission. The TOD-caused chirp affects most fast and strongly; on one side, it takes on unchanged outline, on the other side, its outline and spot of peak value change during the transmission. The peculiar character of SS-caused chirp is the ascendant on the trailing edge over the leading edge. And the ISRS-caused chirp is large and mainly change more complicatedly than the second-order soliton's chirp on the trailing edge after transmitting for about 2 soliton cycle length.