Polarization dynamics in nonlinear anisotropic fibers

Abstract

We give an extensive study of polarization dynamics in anisotropic fibers exhibiting a third-order index nonlinearity. The study is performed in the framework of the Stokes parameters with the help of the Poincaré sphere. Stationary states are determined, and their stability is investigated. The number of fixed points and their stability depend on the respective magnitude of the linear and nonlinear birefringence. A conservation relation analogous to the energy conservation in mechanics allows evidencing a close analogy between the movement of the polarization in the Poincaré sphere and the motion of a particle in a potential well. Two distinct potentials are found, leading to the existence of two families of solutions, according to the sign of the total energy of the equivalent mechanical system. The mechanical analogy allows us to fully characterize the solutions and also to determine analytically the associated beat lengths. General analytical solutions are given for the two families in terms of Jacobi's functions. The intensity-dependent transmission of a fiber placed between two crossed polarizers is calculated. Optimal conditions for efficient nonlinear switching compatible with mode-locking applications are determined. The general case of a nonlinear fiber ring with an intracavity polarizer placed between two polarization controllers is also considered.

Polarisation Dynamics of Vector Soliton Molecules in Mode Locked Fibre Laser

“…As shown by Akhmediev, Soto-Crespo26 and Komarov et al45, the eigenstates for a fibre with the linear birefringence and circular birefringence can be found as follows (Fig. 7 (a)): Here S 0 = const and α is determined by the ratio of linear to circular birefringence strength.…”

“…Unlike polarisation dynamics of vector solitons on the Poincaré sphere demonstrated by Akhmediev, Soto-Crespo26 and Komarov et al45, we study experimentally how polarisation hole burning in an active medium46474849 contributes to the polarisation dynamics. All results are obtained based on inline polarimeter (OFS TruePhase IPLM) optimised for high-speed operation505152.…”

Manipulating dissipative soliton ensembles in passively mode-locked fiber lasers

“…To favor multiple-pulse mode locking, the total dispersion is set in the anomalous regime with b DCF 2 L ¼ À0:16 ps 2 , with a total cavity length of L = 32.5 m corresponding to a round trip time of 162.4 ns and to a free spectral range of 6.16 MHz. Mode-locking is obtained thanks to the nonlinear polarization evolution technique based on nonlinear losses resulting from a polarizing isolator placed between two fibered polarization controllers [31]. As usual, the adjustment of the polarization controllers allows obtaining a large variety of soliton distributions [15].…”

Vector solitons in harmonic mode-locked erbium-doped fiber lasers

“…Harmonic MLFLs based on carbon nanotubes (CNTs) demonstrated sub-picosecond pulses at high repetition rates 26 .We present experimental study of polarization attractors of fundamental and harmonic mode-locked regimes for two fiber lasers with different gain fibers. Unlike polarization dynamics of vector solitons on the Poincaré sphere demonstrated by Akhmediev, Soto-Crespo 27 and Komarov et al 28 , we demonstrate new insight related to contribution of polarization hole burning in an active medium to the polarization dynamics.…”

“…CNTs films preparation and characterization was as described in Ref. 28. In experiments, the pump current of the laser diode was increased and various polarization attractors were obtained by varying both the in-cavity and pump PCs for a given pump power.…”