Nanostructured Plasmonic Metal Surfaces as Optical Components for Infrared Imaging and Sensing.


Authors: J. Mandal,* J. Brewer, S. Mandal, A. Raman*.

Preprint: Posted on arXiv (2021-06-27).

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Summary: Thermal imaging and sensing technologies offer critical information about our thermally radiant world, and in recent years, have seen dramatic increases in usage for a range of applications. However, the cost and technical finesse of manufacturing infrared optical components remain a major barrier towards the democratization of these technologies. In this report, we present a solution-processed plasmonic reflective filter (PRF) as a scalable and low-cost thermal infrared optic. The PRF selectively absorbs sunlight and specularly reflects thermal infrared (TIR) wavelengths with performance comparable to state-of-the-art TIR optics made of materials like Germanium. Unlike traditional infrared optical components, however, the PRF can be conveniently fabricated using low-cost materials and a ‘dip-and-dry’ chemical synthesis technique, and crucially, has manufacturing costs that are orders of magnitude lower. We experimentally demonstrate the PRF’s core optical functionality, as well as its integration into infrared imaging and sensing systems without compromising their thermographic or radiometric capabilities. From a practical standpoint, the low cost and convenient fabricability of the PRF represent a significant advance towards making the benefits of thermal imaging and sensing systems more affordable and accessible. Scientifically, our work demonstrates a previously unexplored optical functionality and a new direction for versatile chemical synthesis in designing optical components.

Scalable, Low-temperature ‘Dip-and-dry’ Technique to Fabricate Plasmonic Selective Absorber for High-efficiency Solar-thermal Energy Conversion

Authors: J. Mandal, D. Wang, A. Overvig, N. Shi, D. Paley, A. Zangiabadi, Q. Cheng, K. Barmak, N. Yu, Y. Yang.

Link: Advanced Materials 29 (41), 201702156 (2017).

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Summary: This work describes a “high-school chemistry”-based technique for making selective solar absorbers.

Selective solar absorbers are surfaces that are black and absorb sunlight, but unlike typical black surfaces, they do not radiate and lose heat. Therefore under sunlight, these surfaces become much hotter than typical black surfaces. The heat these surfaces capture from the sun can be used for heating or boiling water, desalination and even generating electricity – so these surfaces can be quite useful.

To my knowledge, the technique for making selective solar absorbers described in this paper is one of the easiest, fastest and most tunable, but yields high optical performance (wide angle solar absorptance > 96% and hemispherical thermal emittance < 10%) nonetheless. Given its scalability, it may be promising for widespread use.