Minin I V, Geints Yu E, Zemlyanov A A, Minin O V
Opt Express. 2020 Jul 20;28(15):22690-22704. doi: 10.1364/OE.400460.
A specular-reflection photonic nanojet (s-PNJ) is a specific type of optical near-field subwavelength spatial localization originated from the constructive interference of direct and backward propagated optical waves focused by a transparent dielectric microparticle located near a flat reflecting mirror. The unique property of s-PNJ is reported for maintaining its spatial localization and high intensity when using microparticles with high refractive index contrast when a regular photonic nanojet is not formed. The physical principles of obtaining subwavelength optical focus in the specular-reflection mode of a PNJ are numerically studied and a comparative analysis of jet parameters obtained by the traditional schemes without and with reflection is carried out. Based on the s-PNJ, the physical concept of an optical tweezer integrated into the microfluidic device is proposed provided by the calculations of optical trapping forces of the trial gold nanosphere. Importantly, such an optical trap shows twice as high stability to Brownian motion of the captured nano-bead as compared to the conventional nanojet-based traps and can be relatively easy implemented.
镜面反射光子纳米射流（s-PNJ）是一种特殊类型的光学近场亚波长空间局域化现象，它源于由位于平面反射镜附近的透明介电微粒子聚焦的直接传播和反向传播光波的相长干涉。当使用具有高折射率对比度的微粒子且未形成常规光子纳米射流时，s-PNJ具有保持其空间局域化和高强度的独特特性。对在PNJ的镜面反射模式下获得亚波长光学焦点的物理原理进行了数值研究，并对通过传统无反射和有反射方案获得的射流参数进行了对比分析。基于s-PNJ，通过对试验性金纳米球的光阱力计算，提出了集成到微流控装置中的光镊的物理概念。重要的是，与传统的基于纳米射流的光阱相比，这种光阱对捕获的纳米珠的布朗运动表现出两倍的稳定性，并且相对容易实现。
