In this paper, firstly, effects of third order dispersion (TOD) on coupled pulses are analyzed. Then, averaging method is modified and proved to be an effective way for obtaining non-radiative bi-soliton solution of the TOD perturbed nonlinear Schrodinger equation (NLSE), which models a dispersion managed (DM) optical transmission system. Finally, the obtained bi-soliton evolution behavior is studied, and compared with that of uni-soliton. With the increase of average TOD, pulse velocity of bi-soliton largely deviates from that of uni-soliton. Thus, even though TOD cannot be exactly vanished in fabrication, it is suggested to compensate average TOD as low as possible.

The power of laser radar received echoes varies over a large range due to many factors such as target distance, size, reflection ratio, etc, which leads to the difficulty of decoding codes from the received noise buried signals for spectrum code modulated laser radar. Firstly, a pseudo-random noise (PN) code modulated laser radar model is given, and the problem to be addressed is discussed. Then, a novel method based on Inter Symbol Interference (ISI) is proposed for resolving the problem, providing that only Additive White Gaussian Noise (AWGN) exists. The ISI effect is introduced by using a high pass filter (HPF). The results show that ISI improves laser radar receiver decoding ratio, thus the peak of the correlation function of decoded codes and modulation codes. Finally, the effect of proposed method is verified by a simple experiment.