Au纳米颗粒阵列中双光子吸收的饱和过程

The two-photon absorption saturation process in an Au nanoparticle array

采用纳米球蚀刻法制备了Au纳米颗粒阵列.并通过扫描电子显微镜观测了其表面形貌,表明三角形的Au纳米颗粒呈阵列状分布.采用Z扫描方法(800nm,50fs)测量了Au纳米颗粒阵列的三阶非线性光学特性.在较小的激发功率下,结果呈现出双光子吸收效应,随着激发功率不断增加,出现了双光子吸收饱和的过程;非线性折射则呈现出自散焦效应.这种高效率的非线性响应机理使得该种Au纳米颗粒阵列在高速全光开关中有潜在的应用价值.

The triangular Au nanoparticle array of size 37 nm was fabricated on a quartz substrate using nanosphere lithography. By performing the Z-scan method with femtosecond laser （800 nm,50 fs）,the optical nonlinearity of the Au nanoparticle array was determined. The results showed an intensity-related two-photon absorption saturation processes. As the excitation intensity increases,the nonlinear absorption changes from two-photon absorption to saturated absorption,while the nonlinear refraction exhibits self-defocusing effect. The one-and two-photon figures of merit,W = 7. 5 and T = 0. 12, were obtained,validating a high efficiency nonlinear material for all-optical switching.