In recent years, novel two-dimensional (2D) materials have revolutionized the field of ultrafast laser technology. They have emerged as efficient, cost-effective, and universal saturable absorbers for the so-called ultrafast lasers, which emit ultrashort optical pulses (on the timescale of femtoseconds). Thanks to their unique optical properties, such as broadband absorption, short recovery time, low saturation fluence, and high modulation depth, they might be used as saturable absorbers for

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... ferent lasers (solid state, fiber, semiconductor) operating at different wavelengths (ranging from 500 to 2500 nm). Such lasers may find various applications in different areas of industry, medical procedures, precise metrology, gas sensing, laser spectroscopy, etc. This chapter discusses the recent achievements in the area of ultrafast fiber lasers utilizing 2D materials: graphene, topological insulators (Bi 2 Te 3 , Bi 2 Se 3 , Sb 2 Te 3 ), transition metal dichalcogenides (MoS 2 , WS 2 , etc.), and black phosphorus. The optical properties of those materials will be described. Their usability in ultrafast photonics will be discussed.