Nonlinear photoresponse of metallic graphene-like VSe2 ultrathin nanosheets for pulse laser generation

Vanadium diselenide (VSe 2 ), a typical metallic behaviour material among transition metal dichalcogenides (TMDCs) family, exhibits excellent photoelectric characteristics with a zero band gap, missing applicaiotn in pulse generation. In this work, a high-quality VSe 2 saturable absorber (SA) was synthesized through a liquid-phase exfoliation method. The saturable absorption of obtained VSe 2 -SA was characterized systematically. The measured modulation depth was 9.9%, and the saturated intensity was 533.8 µJ/cm 2 . By incorporating this optical modulator into a ytterbium-doped fiber laser cavity, a stable passively Q-switched laser could be achieved. The pulse had the central wavelength of 1064.03 nm. As the pump power was increased, the repetition rate increased from 24.3 kHz to 35.6 kHz, and the pulse duration decreased from 7.21 µs to 5.27 µs. The output power had the maximum value of 28.55 mW. These results indicated that VSe 2 is an effective candidate to generate pulse laser due to its excellent nonlinear optical properties and universal photoelectric response, which may advance the applications of VSe 2 -based nonlinear optics and photoelectric devices.