Xing Guichuan, Jiang Jiang, Ying Jackie Y, Ji Wei
Department of Physics, National University of Singapore, Singapore 117542, Singapore.
Opt Express. 2010 Mar 15;18(6):6183-90. doi: 10.1364/OE.18.006183.
We report the observation of optical limiting in Fe(3)O(4)-Ag nanocomposites in solution. With these nanocomposites, we demonstrate that broad temporal optical limiting can be accomplished with low limiting threshold. Due to the presence of Ag nanoparticles, nonlinear scattering gives rise to enhanced optical limiting responses to 532-nm nanosecond laser pulses, with a limiting threshold comparable to carbon nanotubes. As exposed to 780-nm femtosecond laser pulses, the largest value (approximately 10(-44) cm(4)s photon(-1) or 10(6) GM) for two-photon absorption cross-sections reported to date results in superior limiting responses with a limiting threshold as low as 0.04 J/cm(2) or 100 GW/cm(2) for Fe(3)O(4)-Ag (7nm) solution in 1 cm quartz cell. The limiting threshold can be further reduced by increasing Ag particle size through plasmon enhancement or taking advantage of self-defocusing.
我们报道了对溶液中Fe(3)O(4)-Ag纳米复合材料光学限幅现象的观察。利用这些纳米复合材料，我们证明了可以在低限幅阈值下实现宽时间范围的光学限幅。由于存在银纳米颗粒，非线性散射导致对532纳米纳秒激光脉冲的光学限幅响应增强，其限幅阈值与碳纳米管相当。当暴露于780纳米飞秒激光脉冲时，迄今为止报道的双光子吸收截面的最大值（约10(-44)平方厘米秒光子(-1)或10(6) GM）导致了优异的限幅响应，对于1厘米石英池中Fe(3)O(4)-Ag（7纳米）溶液，限幅阈值低至0.04焦耳/平方厘米或100吉瓦/平方厘米。通过等离子体增强增加银颗粒尺寸或利用自散焦可以进一步降低限幅阈值。
