Nonlinear optical response of a monolayer WS 2 and the application of a hundred-MHz nanosecond laser

Abstract

High quality monolayer WS 2 was successfully fabricated by chemical vapor deposition method. The nonlinear optical response of monolayer WS 2 is demonstrated for the first time. Due to the relatively low modulation depth of 1.4% and saturable intensity of 68.6 kW/cm 2 of monolayer WS 2 , a robust continuous-wave mode-locked (CWML) nanosecond laser with a repetition rate of 93.1 MHz is obtained. To the best of our knowledge, this is the highest repetition rate of nanosecond pulses generated from CWML lasers. This work provides an effective approach to obtaining nanosecond pulsed lasers with repetition rates of hundred-megahertz.