The year 2019 marks the 10th anniversary of the first report of ultrafast fiber laser mode-locked by graphene. This result has had an important impact on ultrafast laser optics and continues to offer new horizons. Herein, we mainly review the linear and nonlinear photonic properties of two-dimensional (2D) materials, as well as their nonlinear applications in efficient passive mode-locking devices and ultrafast fiber lasers. Initial works and significant progress in this field, as well as new insights and challenges of 2D materials for ultrafast fiber lasers, are reviewed and analyzed.

Silicon (Si) photonics have established as leading technologies in addressing the rapidly increasing demands of huge data transfer in optical communication systems with compact footprints, small power consumption, and ultradense bandwidth, which are driven by the next generation supercomputers and big data era. Particularly, Si photonics will penetrate into optical communication links at an ever-small scale, namely chip-to-chip and on-chip. However, the nanostructures made of Si with an indirect bandgap are not ideal candidates for on-chip light sources, modulators, and photodetectors, which most-frequently require optical materials with direct bandgap. Thanks to the advent of graphene, transition metal dichalcogenides and other two-dimensional (2D) materials, which can facilitate extraordinary progresses in improving device performance at the ultrathin scale, their integration with Si photonics furnishes a heterogeneous platform to construct fully functional and highly integrated photonic communication systems. In this work, the current advancements in the on-chip applications of Si photonics-2D materials heterostructures, inclusive of all essential chip-scale modules and integrated circuits, as well as the future prospective and challenges are reviewed and discussed. The present study sets out to objectively measure the feasibility of the hybrid integration between Si photonics and 2D materials in on-chip optical communications and the advanced applications beyond.

We reported diverse soliton operations in a thulium/holmium-doped fiber laser by taking advantage of a tapered fiber-based topological insulator (TI) Bi 2 Te 3 saturable absorber (SA). The SA had a nonsaturable loss of ∼53.5% and a modulation depth of 9.8%. Stable fundamentally mode-locked solitons at 1909.5 nm with distinct Kelly sidebands on the output spectrum, a pulse repetition rate of 21.5 MHz, and a measured pulse width of 1.26 ps were observed in the work. By increasing the pump power, both bunched solitons with soliton number up to 15 and harmonically mode-locked solitons with harmonic order up to 10 were obtained. To our knowledge, this is the first report of both bunched solitons and harmonically mode-locked solitons in a fiber laser at 2 μm region incorporated with TIs.

Engineering 2D‐structured lead halide perovskites leads to both excellent optoelectronic performance and intriguing photophysics. Here, the underlying mechanisms of exciton interaction and carrier transfer in 2D/3D hybrid perovskites are studied. The investigated perovskites are in the form of self‐assembled microplatelets, which are naturally composed of multiple perovskite phases, with n being 1, 2, 3, or 4 or nanocrystals in bulk phase (n ≈ ∞). Excitonic energy transfer and charge separation between different phases are found to coexist in this hybrid system, which occur at an ultrafast timescale (<100 fs) followed by a relatively slow channel (2–15 ps). The experimental results reveal that this hybrid perovskite naturally forms a series of “heterostructures,” with excitons generated in different phases, showing Coulomb interactions across the interface. This interlayer Coulomb coupling should account for the aforementioned ultrafast carrier transfer. This work provides an accurate and thorough explanation for the remarkable charge transfer rate, which is extremely beneficial for their applications in photovoltaic and optoelectronic devices, even with the apparent interfacial scattering, defect trapping, and disorder‐induced exciton localization in 2D/3D hybrid perovskites.

All-fiber-integrated mid-infrared (mid-IR) supercontinuum (SC) generation in a single mode ZBLAN (ZrF4-BaF2-LaF3-AlF3-NaF) fiber with 13 W average output power and a spectrum extending from ∼1.9 to 4.3 μm is reported, which we believe is the highest output power for mid-IR SC generation in ZBLAN fibers. The overall optical conversion efficiency from the 790 nm pump light of the last stage Tm-doped fiber (TDF) amplifier to the total SC output was 20%, and the SC power for wavelengths longer than 2.5 μm was 6.85 W with a power ratio of 52.69% with respect to the total SC power. The mid-IR SC generation in ZBLAN fiber was pumped by a 2 μm master oscillator power amplifier (MOPA) system, which is also very appropriate for high power 2-2.5 μm region SC generation. We also demonstrate high efficiency SC generation in the TDF amplifier with 62.1 W average power, 39.8% optical efficiency, and a spectrum extending from 1.9 to 2.7 μm.