Gummaluri Venkata Siva, Nair Radhika V, Krishnan S R, Vijayan C
Opt Lett. 2017 Dec 1;42(23):5002-5005. doi: 10.1364/OL.42.005002.
In this Letter, we report on the design, fabrication, and implementation of a novel plasmon-mode-driven low-threshold near-infrared (NIR) random laser (RL) in the 850-900 nm range based on plasmonic ZnS@Au core-shell scatterers. Plasmon modes in the NIR region are used for nanoscale scatterer engineering of ZnS@Au core-shell particles to enhance scattering, as against pristine ZnS. This plasmonic scattering enhancement coupled with femtosecond (fs) laser pumping is shown to cause a three-fold lasing threshold reduction from 325 μJ/cm to 100 μJ/cm and a mode Q-factor enhancement from 200 to 540 for ZnS@Au-based RL, as compared to pristine ZnS-based RL. Local field enhancement due to plasmonic ZnS@Au scatterers, as evidenced in the finite-difference time-domain simulation, further adds to this enhancement. This work demonstrates a novel scheme of plasmonic mode coupling in the NIR region and fs excitation in a random laser photonic system, overcoming the inherent deficiencies of weak absorption of gain media and poor scattering cross sections of dielectric scatterers for random lasing in the NIR spectrum.
在本信函中，我们报道了一种基于等离子体ZnS@Au核壳散射体、工作在850 - 900纳米范围内的新型等离子体模式驱动的低阈值近红外（NIR）随机激光（RL）的设计、制备及实现。与原始ZnS相比，近红外区域的等离子体模式用于对ZnS@Au核壳颗粒进行纳米级散射体工程设计，以增强散射。结果表明，这种等离子体散射增强与飞秒（fs）激光泵浦相结合，可使基于ZnS@Au的随机激光的激射阈值从325 μJ/cm降低三倍至100 μJ/cm，模式品质因数从200提高到540，而原始ZnS基随机激光则不然。有限时域差分模拟证明，等离子体ZnS@Au散射体引起的局部场增强进一步增加了这种增强效果。这项工作展示了近红外区域等离子体模式耦合和随机激光光子系统中飞秒激发的新方案，克服了增益介质吸收弱以及介电散射体在近红外光谱中随机激光散射截面差的固有缺陷。
