Observation of chaotic polarization attractors from a graphene mode locked soliton fiber laser

We have demonstrated an all-fiber passively mode locked erbium-doped fiber laser(EDFL) based on graphene–polyvinyl-alcohol film. By watchfully adjusting the polarization controller, two different polarization attractors, including polarization locked vector solitons and a circular attractor, can be observed. This is first time, to the best of our knowledge, to explore the dynamics polarization attractors exhibited by a vector soliton generated from an EDFL based on graphene.

Spiral attractor created by vector solitons

Mode-locked lasers emitting a train of femtosecond pulses called dissipative solitons are an enabling technology for metrology,high-resolution spectroscopy,fibre optic communications,nano-optics and many other fields of science and applications.Recently,the vector nature of dissipative solitons has been exploited to demonstrate mode locked lasing with both locked and rapidly evolving states of polarisation.Here,for an erbium-doped fibre laser mode locked with carbon nanotubes,we demonstrate the first experimental and theoretical evidence of a new class of slowly evolving vector solitons characterized by a double-scroll chaotic polarisation attractor substantially different from Lorenz,Ro¨ssler and Ikeda strange attractors.The underlying physics comprises a long time scale coherent coupling of two polarisation modes.The observed phenomena,apart from the fundamental interest,provide a base for advances in secure communications,trapping and manipulation of atoms and nanoparticles,control of magnetisation in data storage devices and many other areas.

Theoretical and experimental analysis of second order Bragg resonance of 45° TFG and its fiber laser application

We report the observation of second order Bragg resonance(2 nd-OBG) produced by tilted fiber gratings(TFGs) fabricated using phase mask UV inscription.The theoretical analysis has revealed that the generation of high order Bragg resonance of gratings is induced by a square-shape refractive index profile,which is caused by over-saturated UV exposure.In the experiment,we have studied the TFGs with different tilt angles under over-saturated UV exposure,in which all gratings have showed the 2 nd-OBR,and the larger tilt angle of the grating has the stronger 2 nd-OBR.When the tilt angle of the grating is-45°,the Bragg resonance exhibits very strong polarization dependence,because the 2 nd-OBR wavelength is located within the polarizing bandwidth of 45° TFG.Finally,we have demonstrated an erbium-doped fiber laser with> 99.9% degree of polarization,and,by applying mechanical stretching on the grating,a wavelength tunable laser output has been achieved.The output laser shows ~0.2 dB amplitude variation within 1 h continuous monitoring of the laser.