Department of Materials Science and Engineering, Plasmonics and Perovskites Laboratory, Indian Institute of Technology Kanpur, UP, 208016, India.
Sci Rep. 2018 Jan 18;8(1):1127. doi: 10.1038/s41598-018-19571-z.
Here, we have numerically calculated electric field intensity and phase of the emission from various hybrid spiral plasmonic lenses (HSPL) in near field as well as in far-field. We have proposed a novel HSPL inscribed with nano corrals slit (NCS) and compared its focusing ability with other HSPLs inscribed with circular slit and circular grating. With the use of nano corrals slit, we have been able to improve light intensity in the far-field without compromising near-field intensity. Our NCS-HSPL outperforms other HSPLs and standalone SPL in near-field as well as far-field. We have also found that proposed circular slit diffractor is far more superior than previously reported circular grating diffractor. We have been able to extend the focal length of hybrid plasmonic lens upto 3 um and observed a two-fold increment in the far field intensity compared to existing spiral plasmonic lens even though size of focal spot remains same. Optical complex fields produced by NCS based HSPL can be used for various applications such as super resolution microscopy, nanolithography, bioimaging and sensing, angular momentum detectors, etc. Moreover, enhanced near-field intensity in conjunction with far-field superfocusing with reasonable focal length may lead to the development of novel multifunctional lab-on-chip devices.
在这里，我们通过数值计算了各种混合螺旋等离子体透镜（HSPL）在近场和远场中的发射电场强度和相位。我们提出了一种新型的 HSPL，其内部刻有纳米笼狭缝（NCS），并将其聚焦能力与其他刻有圆形狭缝和圆形光栅的 HSPL 进行了比较。通过使用纳米笼狭缝，我们能够在不影响近场强度的情况下提高远场中的光强。我们的 NCS-HSPL 在近场和远场中都优于其他 HSPL 和独立的 SPL。我们还发现，所提出的圆形狭缝衍射器比以前报道的圆形光栅衍射器优越得多。我们已经能够将混合等离子体透镜的焦距延长到 3 微米，并观察到远场强度与现有螺旋等离子体透镜相比增加了一倍，尽管焦点光斑的大小保持不变。基于 NCS 的 HSPL 产生的光学复场可用于各种应用，如超分辨率显微镜、纳米光刻、生物成像和传感、角动量探测器等。此外，近场强度的增强与远场超聚焦相结合，合理的焦距可能会导致新型多功能片上实验室设备的发展。
