Researchers have developed a novel tunable optical filter for smart IR night vision imaging systems. They used a new phase-changing material (PCM) called GSST, which goes through a phase transition at a higher transition temperature (around 300°C). It is created by partially substituting selenium for tellurium, resulting in Ge2Sb2Se4Te1.
Compared to Ge2Sb2Te5, the phase-changing material has lower optical loss and a larger index contrast between the two states, making it better suited for optical applications. A pixelated version of the proposed filter can be implemented in smart IR systems to enable real-time reconfigurability.
The proposed filter is a Metal-Insulator-Metal (MIM) cavity easily fabricated as stratified layers without complicated patterning processes. Although MIM has previously been used in tunable optical filter designs with phase-changing material, none presented a systematic approach for designing these structures. The researchers present a well-developed theory for designing MIM and incorporating PCMs easily adaptable to different wavelengths, configurations, and applications.
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