Opt Lett. 2020 Dec 15;45(24):6695-6698. doi: 10.1364/OL.404304.
A nonlinear photoacoustic (PA) response from solutions of 40 nm plasmonic titanium nitride nanoparticles (NPs) synthesized by laser ablation in a liquid environment (acetone) is reported. Using a photoacoustic Z-scan with 5 ns pumping pulses, values of effective nonlinear absorption (NLA) coefficients were measured and found to be 3.27±0.17 × 10, 6.41±0.32 × 10, and 3.22±0.16 × 10 for 600, 700, and 800 nm pumping wavelengths, respectively. To take into account the influence of nonlinear scattering, absorption-dependent PA measurements were carried out together with the optical Z-scan, and the obtained data were compared. The origin of the effective absorptive nonlinearity is discussed based on combined NLA in NPs, nonlinear scattering, and bubble generation triggered by NP-mediated light absorption. Potential applications include biomedical diagnostics and therapy.
本文报道了一种在液体环境（丙酮）中通过激光烧蚀合成的 40nm 等离子体氮化钛纳米粒子（NPs）溶液的非线性光声（PA）响应。使用具有 5ns 泵浦脉冲的光声 Z 扫描，测量了有效非线性吸收（NLA）系数的值，分别为 6.41±0.32×10^-3、3.22±0.16×10^-3 和 3.27±0.17×10^-3，对应的泵浦波长分别为 600nm、700nm 和 800nm。为了考虑非线性散射的影响，进行了与光 Z 扫描结合的吸收相关的 PA 测量，并对获得的数据进行了比较。基于 NPs 中的组合 NLA、非线性散射和 NP 介导的光吸收引发的气泡生成，讨论了有效吸收非线性的起源。潜在的应用包括生物医学诊断和治疗。
