PbSe Nanosheets for High‐Performance Harmonic Mode Locking.

As a new emerging semiconductor with interlayer bandgap, lead selenide (PbSe) have broad prospects in the fields of electrocatalysis, photocatalysis, infrared optoelectronic devices, optoelectronics, and ultrafast photonics. Among them, ultrafast photonics is receiving a lot of attention due to its ultrashort pulse, strong peak power, narrow bandwidth, and high repetition frequency. Herein, the properties are systematically studied of PbSe through various characterization methods. The modulation depth of PbSe is up to 30%, and its saturation light intensity is 7.86 MW cm−2. Using the evanescent field effect, nonlinear fiber‐based photonics devices has been successfully prepared based on the PbSe nanosheet solution, which can increase the bearable pump power. The 36th picosecond harmonic mode‐locked soliton molecule is generated in the erbium‐doped fiber laser, which corresponds to a maximum repetition frequency of 222 MHz. The results show that the signal‐to‐noise ratio can reach up to 49.1 dB which is higher than most previous works by now. The results revealed the potential of PbSe as an excellent photonics material in applications such as nonlinear optics, ultrafast photonics equipment, photoconductive detectors, and light modulators. [ABSTRACT FROM AUTHOR]