Fig. 3

Nonlinear optical responses to ns pulses. a, b Circles: normalized transmission of Bio-Te-PmPV as a function of z at 532 nm and 1064 nm; Squares: light intensity scattered by the sample at 35 degrees to the laser’s direction; Lines: z-scan fitting results. c, d Effective nonlinear extinction (NLE) coefficient β_NLE and corresponding Imχ⁽³⁾ as a function of on-focus intensity for ns pulses at 532/1064 nm. e Effective nonlinear extinction coefficient β_NLE as a function of linear absorption coefficient α₀ with error bars indicating s.e.m. f Comparison of optical limiting performance of Bio-Te-PmPV, PcZn (t-Bu₄PcZn), C₆₀, and single-walled carbon nanotube (SWNT) dispersions at 532 nm, 6 ns irradiation