Liu Longju, Monshat Hosein, Wu Hsin-Yu, Lu Meng
Department of Electrical and Computer Engineering, Iowa State University, Ames, IA 50011, United States of America.
Nanotechnology. 2020 Sep 11;31(37):375302. doi: 10.1088/1361-6528/ab98bf. Epub 2020 Jun 2.
This paper reports an imprint and transfer approach for the rapid and inexpensive fabrication of the ultra-thin freestanding plasmonic membrane (FPM) that supports surface plasmon resonances. The imprint and transfer fabrication method involves the soft imprint lithography on an ultrathin polymer film, transfer of the perforated polymer film to a supporting frame, subsequent deposition of gold, and final removal of the polymer film. Without using any sophisticated lithography and etching processes, the imprint and transfer method can produce freestanding gold membranes with 2D arrays of submicrometer-sized holes that support plasmonic modes in the mid-wavelength infrared (mid-IR) range. Two FPM devices with an array constant of 4.0 and 2.5 μm have been simulated, fabricated, and measured for their transmittance characteristics. The fabricated FPMs exhibit surface plasmon polariton Bloch mode and extraordinary optical transmission (EOT) with the enhanced local field around the membrane. The effects of membrane thickness and angle dispersion on the FPM were investigated to show the tuning of EOT modes in IR. Furthermore, we demonstrated the refractometric sensing and enhanced IR absorption of the FPM device for its potential in chemical and biomolecule sensing applications.
本文报道了一种用于快速且低成本制造支持表面等离子体共振的超薄独立等离子体膜（FPM）的压印和转移方法。该压印和转移制造方法包括在超薄聚合物膜上进行软压印光刻，将穿孔聚合物膜转移到支撑框架上，随后沉积金，以及最终去除聚合物膜。无需使用任何复杂的光刻和蚀刻工艺，压印和转移方法可以制造出具有亚微米级尺寸孔的二维阵列的独立金膜，这些孔在中波长红外（mid-IR）范围内支持等离子体模式。已对两种阵列常数分别为4.0和2.5μm的FPM器件进行了模拟、制造和透射率特性测量。所制造的FPM表现出表面等离子体激元布洛赫模式和超常光学透射（EOT），且膜周围局部场增强。研究了膜厚度和角度色散对FPM的影响，以展示红外中EOT模式的调谐。此外，我们展示了FPM器件在化学和生物分子传感应用中的潜力，即其折射传感和增强的红外吸收特性。
