Intense, ultrashort pulse, vector wave propagation in optical fibers

The planned research is initially motivated by experiments on twisted fiber to examine the polarization of the output pulses. The initial polarization launched into the fiber evolves to a new final state that asymptotically moves to one of two opposite circular polarizations. The initial research was to program the vector wave equations of one and coupled solitons in a twisted fiber including the additional nonlinear terms stimulated Raman scattering and self-steepening. The high-twist fiber eliminates small linear birefringence at the expense of introducing circular birefringence manifested in the group velocities. The vector equations are naturally written in the circular polarization basis. To verify the numerical results, I made a sojourn to INAOE in Puebla, Mexico to run an experiment and compare the results. The numerical compare extremely well with the experimental results. For one soliton, the output polarization of the twisted fiber follows the input with high fluctuations. However, for the coupled soliton input, when the input polarization is close to linear, we observe a very abrupt polarization switch from nearly negative circular, -45° to nearly positive circular, 45° over a very narrow range of the input ellipticities. The literature is full of simulations of super-continuum generation using scalar wave equations, but we have not seen any report on the polarization of the output Supercontinuum light. Again, motivated by the experiments on polarization evolution in optical fibers we wanted to study the vector wave equations at higher incident powers to discover what the polarization state of the output waves are in an extreme nonlinear situation