Experimental Demonstration of Adaptive Infrared Multispectral Imaging using Plasmonic Filter Array.

Woo-Yong Jang,Zahyun Ku,James Park,Sang Jun Lee,Michael J Noyola,Jiyeon Jeon,Augustine Urbas,Jun Oh Kim

doi:10.1038/srep34876

Abstract

In our previous theoretical study, we performed target detection using a plasmonic sensor array incorporating the data-processing technique termed “algorithmic spectrometry”. We achieved the reconstruction of a target spectrum by extracting intensity at multiple wavelengths with high resolution from the image data obtained from the plasmonic array. The ultimate goal is to develop a full-scale focal plane array with a plasmonic opto-coupler in order to move towards the next generation of versatile infrared cameras. To this end, and as an intermediate step, this paper reports the experimental demonstration of adaptive multispectral imagery using fabricated plasmonic spectral filter arrays and proposed target detection scenarios. Each plasmonic filter was designed using periodic circular holes perforated through a gold layer, and an enhanced target detection strategy was proposed to refine the original spectrometry concept for spatial and spectral computation of the data measured from the plasmonic array. Both the spectrum of blackbody radiation and a metal ring object at multiple wavelengths were successfully reconstructed using the weighted superposition of plasmonic output images as specified in the proposed detection strategy. In addition, plasmonic filter arrays were theoretically tested on a target at extremely high temperature as a challenging scenario for the detection scheme.

Highlights

We present the first experimental demonstration of this reconstruction using an array of surface plasmon (SP) spectral filters to measure the radiant power from an unknown source in a scene in the long wave IR (LWIR) region
Prior to the design of the surface plasmon (SP) resonance structures, three requirements were specified by the algorithmic spectrometer for the object detection in long-wave IR (LWIR)
The SP resonance wavelengths were set between 7.5 and 11 μm, the number of resonances was set to be at least 4 or greater, and the the full-width at half maximum (FWHM) bandwidth required was set to 2 μmor less

Summary

Introduction

Cones support daytime vision and the perception of color with three classes, often referred to as the long L peak in the red, the medium M peak in the green, and the short S peak in the blue These three L, M and S cones display different, but partially overlapping response curves. The physical phenomenon of surface plasmon (SP) resonance[12,13,14,15] has been demonstrated to have a high potential for use as multispectral (MS) sensing elements or couplers for IR imagers This is due to the ease of tuning the resonance wavelength, and providing the ability to design transmission and reflection properties, thereby offering different spectral shapes for a sensor’s responsivities. To clarify the difference between our study and previous works reported in refs 18–20 it is worth noting that the proposed plasmonic sensing strategy has not been fully realized prior to this work, i.e., the implantation and performance analysis of IR retina concept was mostly carried out either with a single pixel IR device (experiment: spectrally-reconstructed target’s signature)[19,20] or with a SP-based superpixel (simulation: spatially- and spectrally-reconstructed target signatures)[18]

Methods

Results

Conclusion