Complex dynamics of passively mode-locked fiber lasers with strict polarization control

Abstract

In this work we browse an overview of the complex dynamics that arise in the non-stationary modes of operation of partly mode-locked fiber lasers under strict polarization control. Both ring and figure-eight cavities implementing saturable absorber mechanisms that rely on nonlinear polarization rotation were considered. The use of twisted fiber ensures robust operation, whereas precise polarization adjustments allow tailoring the nonlinear switching characteristic in a clear and repeatable manner. The enhanced flexibility of these sources allowed identifying and studying a broad spectrum of peculiar dynamics, in particular by implementing the temporal and spectral mapping techniques. These include the emergence, fusion, splitting, complex evolution and eventual decay of chaotic bunches of radiation, which are also subject to large spectral shifts, ample quasi-periodic instabilities, extreme-intensity events or the creation of solitons, among others, as well as the complex evolution of massively multiple soliton states. Finally, with the help of numerical simulation, several aspects of the physics underlying these puzzling behaviors could be elucidated.

Numerical study of polarization evolution governed by linear birefringence, twist-induced circular birefringence and nonlinear birefringence in a single-mode optical fiber

“…In a broad number of optical fiber systems, a uniform twist rate is applied along the fiber, such as fiber Bragg gratings [1][2][3], interferometric schemes [4,5], fiber optic sensors based on induced circular birefringence [6][7][8], optical signal processing devices [9], mode-locked fiber lasers (ML-FL) [10][11][12][13][14] and so on. In most of these physical contexts, the twisted optical fiber is part of a strict polarization control scheme based on birefringence and polarization adjustments, which plays an important role in ensuring predictability and reproducibility of the adjustment process.…”