Highly Flexible Infrared Emitter with Spatially Controlled Emissivity for Optical Security

Dongkyun Kang, Yeongseon Kim, Chanhee Kim, Myeongkyu Lee

Research output: Contribution to journalArticlepeer-review


Engineering the infrared (IR) emissivity of a material or structure is crucial for a variety of fields, including thermal camouflage, radiative cooling, personal thermal management, and optical security. For practical and wide-spread use, the emitter should possess high mechanical flexibility while maintaining the capabilities of space-selectively and dynamically controlling its emissivity. In this paper, an optical resonator consisting of a Ge2Sb2Te5 (GST) layer on top of a thin metal reflector stationed on a flexible substrate is presented as an IR emitter that satisfies the aforementioned requirements. A laser-induced phase change from amorphous to crystalline GST enables dynamic tuning of the local emissivity of the resonator. This study illustrates that although GST is a brittle material, the emitters fabricated on plastic and paper substrates are highly robust against bending up to a radius of curvature of 0.5 cm. Moreover, visible light and IR images can be independently recorded in the same region by employing a spatially modulated laser beam owing to the multispectral properties of GST. The fact that a single emitter can exhibit different visible and IR images is particularly attractive for optical security applications, including anti-forgery. This feature is experimentally demonstrated using white paper and color-printed paper.

Original languageEnglish
Article number2200808
JournalAdvanced Materials Technologies
Issue number4
Publication statusPublished - 2023 Feb 24

Bibliographical note

Funding Information:
This work was supported by National Research Foundation of Korea (NRF) grants funded by the Korean government (MSIT) (NRF‐2020R1A2C2003575 and NRF‐2022M3H4A1A02046445) and a Korea Agency for Infrastructure Technology Advancement (KAIA) grant funded by the Ministry of Land, Infrastructure and Transport (Grant 21CTAP‐C163910‐01).

Publisher Copyright:
© 2023 Wiley-VCH GmbH.

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Mechanics of Materials
  • Industrial and Manufacturing Engineering


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