Research On The Multiple Laser Pulse Interaction And Control Mechanism In Optical Fiber

It is very important to realize all-optical controlling and improving quality of laser pulse in optical fiber.Through soliton trapping can realize the control of low-power pulse by high-power pulse.In order to better apply soliton trapping to optical communication technology,a clear and systematic analysis of the soliton trapping conditions and regularities should be needed.The stacked pulse is formed by superposition of the several sub-pulses interaction for easier realizing the control of high-power laser and improving quality of laser pulse.In order to better reflect the nonlinear interaction in the process of stacked pulse propagation and study the propagation variation regularity of a single pulse,need to use the propagation model which based on the nonlinear interaction between the sub-pulses to study the propagation characteristics of the stacked pulse.Firstly,we draw on the experience of the nonlinear Schrodinger equation of the single pulse propagation in single-mode fiber nonlinear,discuss the nonlinear propagation evolution equation when two pulses interaction propagation in the optical fiber,and generalize the nonlinear propagation evolution equation of two pulses to multiple pulse interaction propagation.Secondly,we theoretically and numerically investigate the systematic trapping regularity of the low-power soliton by the high-power laser that the low-power laser pulse can be captured as soliton or quasi-soliton,the low-power quasi-soliton demonstrate cyclical evolution.The trapped pulse is a central symmetry low-power soliton when the low-power pulse is almost completely captured,but it is developed into an asymmetric quasi-soliton when the low-power pulse is partially captured.Half of the asymmetric quasi-soliton is the same with the soliton profile,while the other half is wider than the soliton profile.The asymmetry of the trapped pulse leads to the cyclical evolution,and the more asymmetric the pulse is,the broader evolution the amplitude will become.The low-power trapped soliton or qusi-soliton can be obtained from any bell-shaped pulses.Lastly,we use the nonlinear propagation model based on cross-phase modulation between the sub-pulses to research the nonlinear propagation and peak-to-average power ratio(PAPR)of the stacked pulses,and give the approximate value of the sub-pulses delay for different types of stacked pulse shape can basically remain unchanged in the process of nonlinear propagation.It is found that when the sub-pulses of the stacked pulse all overlapped,time-coherent will lead to interaction between the sub-pulses and change the quality of sub-pulses in the process of propagation.Under the condition of different sub-pulses delay,the intensity and PAPR of the stacked pulse occur different degrees of change during the propagation,and their variation amplitude decreases with the sub-pulses delay.