Topological Insulators: An In-Depth Review of Their Use in Modelocked Fiber Lasers

Abstract

Topological insulators (TIs) exhibit exciting optical properties, which open up a new pathway to generate ultrashort pulses from fiber lasers. Layered TIs display distinct saturable absorption properties due to excited state absorption, as compared to their bulk structures. Moreover, the electronic structures of the TI films depend on the thickness of the films due to the quantum confinement of the electrons. By virtue of this, TI nanoparticles play a key role in all-fiber modelocked lasers. By tweaking the crystal structures of TIs, it is possible to generate ultrashort pulses across the visible, near-infrared, and mid-infrared wavelengths. Starting from the crystal structures and density of states calculations, how different topological insulators can be fabricated and integrated as an efficient passive saturable absorber in all-fiber modelocked lasers with the capability of producing fundamental to high-harmonic pulse generation are described clearly in this review report. Moreover, this report reviews the current state-of-art of TI-based saturable absorbers and their applications in different regimes of modelocked fiber�lasers. � 2021 Wiley-VCH GmbH