We demonstrate a novel approach to show high-contrast thermo-optical switching by profiting from the solid–liquid phase transition of CuCl nanocrystals embedded in a transparent borosilicate glass. These nanostructured glasses exhibit a distinct excitonic absorption in the near-UV region (369 nm), which undergoes significant modulation upon thermally induced phase changes of the CuCl nanocrystals. Exploiting the low melting point of CuCl relative to the glass matrix, we achieve thermally reversible solid–liquid–solid transitions, producing a pronounced optical hysteresis effect. Notably, by heating beyond the melting point, an approach that has not previously explored, we observe a larger and extended optical hysteresis contrast than reported in earlier studies, and with a distinct sail-like shape. Furthermore, we show that these transitions can be selectively interrupted at different heating (cooling) stages, enabling multilevel analog optical switching. These findings highlight the exceptional potential of CuCl-doped glasses as a robust, sustainable and tunable platform for advanced optoelectronic applications, paving the way for innovative optical memory and signal processing technologies.

This work was funded by the Spanish Research Agency (AEI, Ministry of Research, Innovation and Universities) and the European Regional Development Fund (ERDF) funded by MCIN/AEI/10.13039/ 501100011033, by Plan de Recuperacion, Transformacion y Resiliencia, and by the “European Union Next Generation EU/PRTR” under grants PID2021-123190OB-I00, TED2021-129666B-C22, and by the CSIC (PIE- 202050E195). EHP acknowledges the support of Consejo Nacional de Humanidades, Ciencias y Tecnologías (CONAHCYT) of Mexico for financial support. We thank Ing. Patricia Castillo Ocampo of UAM- Iztapalapa for the HRTEM measurements.

7 pages, 7 figures

Peer reviewed