Dynamics of carbon nanotube-based mode-locking fiber lasers

Carbon nanotube (CNT) can work as excellent saturable absorber (SA) due to its advantages of fast recovery, low saturation intensity, polarization insensitivity, deep modulation depth, broad operation bandwidth, outstanding environmental stability, and affordable fabrication. Its successful application as SA has promoted the development of scientific research and practical application of mode-locked fiber lasers. Besides, mode-locked fiber laser constitutes an ideal platform for investigating soliton dynamics which exhibit profound nonlinear optical dynamics and excitation ubiquitous in many fields. Up to now, a variety of soliton dynamics have been observed. Among these researches, CNT-SA is a key component that suppresses the environmental perturbation and optimizes the laser system to reveal the true highly stochastic and non-repetitive unstable phenomena of the initial self-starting lasing process. This review is intended to provide an up-to-date introduction to the development of CNT-SA based ultrafast fiber lasers, with emphasis on recent progress in real-time buildup dynamics of solitons in CNT-SA mode-locked fiber lasers. It is anticipated that study of dynamics of solitons can not only further reveal the physical nature of solitons, but also optimize the performance of ultrafast fiber lasers and eventually expand their applications in different fields.