Bulk-structured PtSe for femtosecond fiber laser mode-locking.

The interest in pulsed fiber laser technology surrounds lots of critical optoelectronic applications ranging from optical communications, remote sensing to industrial material processing. Here, a femtosecond Er-doped fiber laser at 1560 nm have been demonstrated by using bulk-structured transition metal dichalcogenides (TMDs) - PtSe as the pulse modulator. The PtSe modulator was fabricated by using mechanically exfoliated methods from its single crystal and the exfoliated PtSe was directly transferred to the polished surface of the D-shaped fiber. Due to the strong interaction between PtSe and evanescent field, a self-starting Q-switched operation can be obtained. Furthermore, the mode-locking operation can be achieved easily by controlling the intra-cavity polarization states. Stable mode-locked operation can be maintained with pulse duration of 861 fs and signal to noise ratio (SNR) of 61.1 dB. These experimental results can validate the excellent nonlinear optical performance of PtSe, and may make inroads for the ultrafast applications of the bulk and low-dimensional TMDs.