Abstract

Background: The physics of graphene, the most recently discovered allotrope of carbon, is currently one of the most extensively studied branches of condensed-matter science. Graphene has attracted great attention of the photonics community in the last years. Thanks to its unique optical properties, like broadband absorption, ultrashort recovery time and large modulation depth, it is currently widely used as universal saturable absorber for mode-locking of fiber lasers operating at different wavelengths.

Methods: The paper summarizes the most prominent recent achievements in the field of graphenebased mode-locked fiber lasers. The unique optical properties of graphene are also discussed. The recent experimental results reported in the literature are described and compared.

Results: The historically first graphene-based fiber lasers were developed in 2009 independently by the groups from Singapore and United Kingdom. Shortly after those reports, a number of papers appeared, demonstrating novel concepts of ultrafast lasers utilizing various forms of graphene, most popularly epitaxially grown and exfoliated (mechanically or in liquid phase). Unique nonlinear optical properties of graphene allowed to achieve many outstanding results and revolutionize the field of ultrafast laser science. Fiber lasers operating at different wavelengths, ranging from 1 to 2 µm were demonstrated, with pulse durations at the level of femtoseconds.

Conclusion: The recent most important advances in the field of ultrafast lasers utilizing graphene have been summarized. Thanks to its unique nonlinear optical properties, graphene has revolutionized the field mode-locked, ultrashort-pulsed fiber lasers. Graphene-based saturable absorbers might be developed in various techniques and they constitute a low-cost and robust alternative to semiconductor-based saturable absorbers. The ongoing research on graphene will surely lead to another, extremely interesting photonics applications of this material in the next years.

Keywords: Fiber lasers, graphene, mode-locked lasers, saturable absorbers, ultrafast lasers.

Graphical Abstract