PVP-Assisted Solvothermal Synthesis of High-Yielded Bi2Te3 Hexagonal Nanoplates: Application in Passively Q-Switched Fiber Laser

Abstract

High-yielded Bi2Te3 hexagonal nanoplates were fabricated via a facile solvothermal method with the assistance of poly (vinyl pyrrolidone) (PVP). Effects of PVP molecular weight and concentration on the morphology and size distribution of the products were illustrated in this study. Molecular weight of PVP is significant for determining the morphology of Bi2Te3. The hexagonal nanoplates with high yield were obtained in the presence of PVP with molecular weight of 40000–45000. The average size and size distribution of Bi2Te3 nanoplates can be slightly varied by controlling concentration of PVP. High-yielded Bi2Te3 nanoplates exhibit characteristics of saturable absorption, identified by open-aperture Z-scan technique. The synthesized Bi2Te3 nanoplates with large saturation intensity of 4.6 GW/cm2 and high modulation depth of 45.95% generated a stable passively Q-switched fiber laser pulse at 1.5 μm. In comparison with recently reported Q-switched fiber lasers utilizing exfoliated Bi2Te3 nanosheets, our passive Q-switching operations could be conducted at a relatively low threshold power of 30.2 mW or a quite high output power of 99.45 mW by tuning the cavity parameters.

High-quality and Large-size Topological Insulator Bi2Te3-Gold Saturable Absorber Mirror for Mode-Locking Fiber Laser

“…The calculated saturation intensity I sat , using I sat  =  F sat / τ A with the recovery time of SAs τ A  = 5.7 ps from ref. 51, is about 19 MW/cm 2 , which is comparable with I sat  = 26.7 MW/cm 2 for the Bi 2 Te 3 film deposited on microfiber by PLD57 but it is much less than 180 MW/cm 2 and 4.6 GW/cm 2 for Bi 2 Te 3 -nanosheets and Bi 2 Te 3 -nanoplates in refs 36 and 37, respectively. The large variation of saturation intensity could be due to that they are strongly dependent on the morphology and size (surface-to-volume ratio) of the Bi 2 Te 3 3758.…”

“…Although the mechanical exfoliation and bulk-structured TI methods can obtain low-cost and high-quality TI films by using scotch tape to repeatedly peel the film from the surface of the bulk crystal, it has the lowest repeatability. Furthermore, the wet chemical synthesis method is widely applied to obtain low-cost few-layer nanomaterials that are usually doped into polyvinyl acetate (PVA) to form TI/PVA film3637 and to be sandwiched between two fiber ferrules in laser cavity. However, the PVA-based SAs have less uniformity and are less liable to optical damage by high intracavity power and mechanical damage by fiber connectors.…”

Thermal Stability and Anisotropic Sublimation of Two-Dimensional Colloidal Bi2Te3 and Bi2Se3 Nanocrystals

“…The presence of PVP is known to have an important role in stabilizing and controlling the morphology of metal–chalcogenide nanoparticles produced by different routes, although the exact mechanisms have not been fully clarified. In addition to controlling the kinetics of different chemical reactions during the solution-based synthesis, PVP is also believed to preferentially bind to the outermost basal Te­(Se) planes of Bi 2 Te 3 (Bi 2 Se 3 ) during their one-pot synthesis thus contributing to the platelet-like morphology of the crystals. , In order to eliminate any possible effect that PVP may have on the stabilities of different crystal facets, the sublimation mechanism of three types of surfactant-free Bi 2 Te 3 NCs was also investigated. Figure S6 shows that the sublimation mechanism of the colloidal Bi 2 Te 3 NCs from which the PVP shell had been removed by the ligand-removal washing procedure , is analogous to that observed with the PVP-capped NCs.…”

Tris‐(8‐hydroxyquinoline) aluminium thin film as saturable absorber for passively Q‐switched erbium‐doped fibre laser

“…A 50/50 optical coupler was used to keep 50% of the oscillating light in the cavity and to extract another 50% for performance monitoring of the fibre laser. A high tap ratio coupler will enhance the output power and the signal-tonoise ratio (SNR) [55] and also reduce the pulse energy fluctuation [56]. The cavity length was estimated to be ∼6 m. The oscilloscope trace, output optical spectrum, and radio frequency (RF) spectrum of the output signal were all monitored simultaneously by 350 MHz oscilloscope with 2 GHz photodetector, optical spectrum analyser, and 7.8 GHz RF spectrum analyser, respectively.…”