Abstract
Abstract MXene as a novel two-dimensional (2D) material exhibits a lot of advantages in nonlinear optics. However, the common MXene, Ti3C2Tx and Ti2CTx nanosheets, easily suffer from degradation under ambient conditions, greatly limiting their practical applications. Here, we demonstrated one of MXene compounds, V2CTx, which has a strong modulation depth (nearly 50%), can serve as an excellent saturable absorber (SA) in passively mode-locked (PML) fiber lasers. More importantly, 206th harmonic order has been successfully generated in Er-doped mode-locked fiber laser, exhibiting maximum repetition rate of 1.01 GHz and pulse duration of 940 fs, which to the best of our knowledge, is the highest harmonic mode-locked fiber laser from the MXene SA so far. In addition, the high harmonic order mode-locked operation can maintain at least 24 h without any noticeable change, suggesting MXene V2CTx nanosheets have excellent stability in this mode-locked fiber laser. It is anticipated that the present work can pave the way to new design for MXene-based heterostructures for high-performance harmonic mode-locked lasers.
Highlights
Mode-locked (PML) fiber lasers have been attracted great attention due to their low-cost, simplification, high beam quality, etc
The crystal structure of the as-prepared V2CTx nanosheets can be further confirmed by High-resolution TEM (HRTEM) and selected area electron diffraction (SAED), shown in Figure 1c, in good agreement with previous demonstrations [48]
The absorption spectrum of the MXene V2CTx nanosheets remains unchanged after MXene V2CTx nanosheets/IPA stored for 10 days, suggesting their excellent stability under ambient conditions, which was evidenced by after-ten-day transmission electron microscope (TEM) measurement (Figure S1)
Summary
Mode-locked (PML) fiber lasers have been attracted great attention due to their low-cost, simplification, high beam quality, etc. Jiang et al reported that MXene Ti3C2Tx was employed as a SA for mode-locking operation at 1066 and 1555 nm, respectively, and a high stable femtosecond laser with pulse duration as short as 159 fs in the telecommunication window was readily obtained [34]. It is crucial to develop the high-performance harmonic mode-locked fiber laser based on MXene SA, including the high repetition rate and excellent stability. By increasing the pump power, 206th harmonic mode-locking can be generated with the central wavelength and 3 dB bandwidth are 1559.1 nm with 3.1 nm, respectively, and the repetition rate can reach up to 1.01 GHz with 940 fs pulse duration, in this work. The high harmonic order mode-locked operation can maintain at least 24 h without any noticeable change, suggesting MXene V2CTx nanosheets have excellent stability in this mode-locked fiber lasers
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