Optical nonlinearities of CVD fabricated graphene by z-scan technique

Optical nonlinearities of single layer graphene were investigated by z-scan method with ps laser pulses at wavelength of 532 nm. In addition to saturable absorption, the inverse saturation absorption was also observed at a higher intensity level. The two-photon absorption coefficient ß and nonlinear refractive index n
₂
are obtained as 0.17 to 5.4 (10
⁵
cm/W) and 0.8 to 10 (cm
²
/GW) respectively, while the pulse intensity was at the range of 6.5 to 97.2 (GW/cm
²
).