An Harmonic Mode-Locked Er-Doped Fiber Laser by the Evanescent Field-Based MXene Ti3C2Tx (T = F, O, or OH) Saturable Absorber

MXenes, as a legendary family of 2D van der Waals nanosheets materials, are extensively studied due to their unique characteristics of broadband nonlinear optical response. In particular, MXenes have excellent nonlinear optical properties of very large nonlinear absorption coefficients and very large nonlinear refractive indexes, which have attracted people's great attentions to study the application of MXenes in photonics, electronics, and optoelectronics in recent years. However, the high-repetition-rate (HRR) ultrafast pulses are not explored based on these kinds of materials. MXene Ti3C2Tx saturable absorber (SA) based on micro-fiber is fabricated by optical deposition method. Here, MXene Ti3C2Tx SA is used to achieve 36th harmonic mode-locking with a repetition rate of 218.4 MHz, a central wavelength of 1566.9 nm, the pulse width of 850 fs, and the spectral width of 3.51 nm. The maximum average output power and pulse energy are 6.95 mW and 0.032 nJ, respectively. This research based on MXene Ti3C2Tx light modulator opens a bright avenue for advanced nonlinear photonics.