Metasurface Enhanced Hyperspectral LWIR Filter

ABSTRACT:We propose to design, develop, and demonstrate a metasurface-enhanced hyperspectral filter suitable for imaging spectrometry applications. The filter is part of a two-stage solution that integrates a patterned micro-antenna metasurface along with a DBR resonant cavity filter capable of creating an extremely narrow-band spectral response. By combining the two spectral filters into one, the out-of-band mode suppression is greatly improved allowing for a broader range of operation. Material alteration in the filter leads to multiple variations in the filter design, which allows for spectral operation ranging from visible to infrared. Fabrication of the filter can be realized through micro-photolithography fabrication process using standard optical materials. Compared to currently available technology, the proposed design provides size, weight, power (SWaP) advantage over existing systems that utilize bulky, external optical components to achieve similar performance. The filter design will be optimized for fast f/# systems and made highly compatible with FPAs. Integration of the filter can be achieved by placement into the line of sight or mounted onto the detector to create a compact detecting solution. Applications using this filter range from hyperspectral sensing at longer ranges than current systems, as well as lower cost sensors for agriculture, object recognition, and homeland security.BENEFIT:We expect the design and fabrication of the proposed effort to result in a metasurface-enhanced hyperspectral pixelated filter for use with standard focal plane arrays (FPAs). Using a two-stage light controlling process, the filter is expected to provide narrower line widths under a fast f/# optical system and be highly scalable for operation at various spectral bands. As a result, the filter will be capable of providing a broader range of operation when compared to the current generation of hyperspectral filters. The fabrication of the proposed filter will be performed using a standard photolithography process, which will result in a compact device that is easily integrated with detectors through a growth or bonding process. Compared to similarly performing hyperspectral filters, this approach is expected to produce a size, weight, and power (SWaP) advantage due to omitting certain bulky optical components. The expected hyperspectral pixelated filter will target both the defense and commercial markets, particularly focusing on object detection, surveillance, remote sensing, defect identification, and chemical imaging.