PROCEEDINGS ARTICLE | February 21, 2013
Proc. SPIE. 8632, Photonic and Phononic Properties of Engineered Nanostructures III
KEYWORDS: Infrared imaging, Nanostructures, Optical filters, Fabry–Perot interferometers, Chemical species, Multispectral imaging, Wave propagation, Infrared radiation, Chemical analysis, Electroluminescent displays
The multispectral imaging technique consists of imaging a given scene at various wavelengths of
interest, each one containing a different spectral information. By analyzing this spectral content,
the chemical species that are present can be localized on the image and identified by reconstructing
their spectral signature. In this way, following Ebbesen's seminal work in plasmonics
[1], purely metallic or hybrid metallodielectric structures [2, 3] seem to be ideal candidates to
perform spectral filtering due to their extraordinary transmission efficiency [4] and polarization
selectivity. Moreover, their compact feature makes it possible for them to gather in wide arrays
of filters that, once integrated into a cooled infrared camera, can achieve real-time multispectral
imaging [5].
As seen in Figure 1.d. the spectral signature reconstruction of a chemical species strongly
depends on the number of filters and their transmission spectra for the designed matrix. In
order to improve the multispectral camera, a complementary approach consists of changing the
filter design to realize a tunable filter whose spectral shape can be adjusted in real time according
to the imaged scene. We focused our attention on the superposition of subwavelength gratings
which seems to be a structure of great potential for multispectral imaging applications [6, 7].
