Observation of optical nonlinearites in strongly quantum confined PbSe nanocrystals for all-optical tunable nanophotonics

The nonlinear refractive index (n 2) and two-photon absorption coefficient (β 2), was determined for PbSe nanocrystals (NCs) suspended in trichloroethylene (TCE) using a standard Z-scan technique with femtosecond pulses over a range of wavelengths in the near-IR. For comparison, the n 2 of PbS NCs in chloroform was also measured. The exciton peaks of the NCs were tuned to telecommunications wavelengths. The concentration of the solutions ranged from 4.5 mg/mL to 18.8 mg/mL.