Experimental Demonstration of Adaptive Infrared Multispectral Imaging using Plasmonic Filter Array

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.

Single-shot on-chip spectral sensors based on photonic crystal slabs

“…The most important example is the color camera that relies three spectral filters: Red(R), Green(G), Blue(B). To go beyond three spectral bands, Fabry-Perot 13 and plasmonic filters 12,27,29 have been developed. However, these resonant filters have simple Lorentz line shapes and lack the spectral diversity to provide high spectral resolution.…”

Mid-infrared plasmonic multispectral filters

“…Nanostructured metal films have been widely used to construct RGB color filters in visible spectrum 11 , 12 , aiming to replace the classical organic color filters in digital cameras. Analogically, metallic microhole arrays (MHAs) were also presented for enhancing transmission of mid-infrared light 13 , 14 , and even terahertz radiation 15 , 16 . Transmission peaks at specific wavelengths could be achieved by properly designing metal MHAs, providing a new approach to realize multispectral infrared photodetectors 17 .…”

Fabry-Perot cavity resonance enabling highly polarization-sensitive double-layer gold grating

“…An IR camera system was used to experimentally compare the linear polarization performance of the single- and the double-layer Au grating structures 28 . The experimental set-up consists of an artificial target with linearly polarized components (a blackbody, a commercial wire grid polarizer, a metal target), the fabricated single- and the double-layer Au grating samples, and a 320 × 256 MWIR type-II InAs/GaSb superlattice based imager.…”