Third-order nonlinear response in cubic concave gold nanoparticles

Concave cubic nanoparticles were theoretically proposed as strong sources of non-linear phenomena such as the optical Kerr effect. In this work, concave cubic gold nanoparticles were prepared by the Turkevich method. A comparison of the third-order susceptibility χ(3) response with regard to the nanoparticle size was realised in the non-resonant regime by the use of the Z-Scan technique. These measurements were done with ultra-short pulses in the near IR (λ = 830 nm). We also studied their temporal dependence in order to obtain the non-thermal non-linear response with the use of a pulse-train chopper.