Analysis of dynamics stability of a twisted fiber external cavity semiconductor laser

We introduce some physical optical effects into a laser to construct a novel laser system. Using a twisted fiber as an optical delay feedback external cavity based on birefringence of twisted fiber, we present a novel delay feedback semiconductor laser system with the twisted fiber effect and establish its physical model, in which the effect of the twisted fiber birefringence is included to lead to dynamics in the laser system. We give linear analysis of stability of the influences of delayed phase and rotation angle of twisted fiber on the oscillation characteristics and behavior of the laser. And we give quantitative analysis of both delayed phase and rotation angle, which resulted from the physical effect of twisted fiber, and analyze to how to alter the relaxation oscillation or dynamics state. Because the twisted fiber can change the direction of light polarization and produce phase shift after light passing through the twisted fiber, the laser system is sensitive to phase change and polarization while some dynamic changes of the laser can be caused and excited. We discovery theoretical that the delayed phase and the rotation angle resulted from the twisted fiber can alter the relaxation oscillation and dynamics state. And the fiber parameter's variety can shift the delayed phase, the rotation angle, the delayed time, and the optical feedback level, so the laser's behavior will vary. We find that the scaling of the transmitting time-delay of fiber and the laser internal timescale creates an incorporation to induce various dynamical scenarios.