Supplement Number 1

Experimental methods of non-degenerate pump-probe measurements, Z-scan and I-scan technique, 3.0 μm Q-switched laser experiment, AFM image and typical height profiles of PtTe2 SA, spectra of CW and Q-switched lasers, beam profiles in the Q-switched operation, repetition rate and pulse width versus the absorbed pump power under different thicknesses of PtTe2, single pulse energy and pulse peak power versus the absorbed pump power under different thicknesses of PtTe2, Q-switched pulsed trains under maximum absorbed pump power and stability measurements of Q-switched operation.