Large purely refractive nonlinear index ofsingle crystal P-toluene sulphonate (PTS) at1600 nm

Abstract
Z-scan measurements at 1600 nm on single-crystal PTS (p-toluene sulfonate) with single, 65 ps pulses gave a complex nonlinear refractive index coefficient of n2 = 2.2(±0.3) × 10-12 cm2/W at 1 GW/cm2 and α2 < 0.5 cm/GW. This is the first highly nonlinear, organic material to satisfy the conditions imposed by the figures of merit.