Tamm plasmon crystals: optical reconfiguration in the visible spectrum

Researchers at the Dalian University of Technology and the University of Hong Kong have developed a novel method for creating dynamically reconfigurable color displays using Tamm plasmonic photonic crystals (TPPCs) integrated with an ultrathin layer of antimony trisulfide (Sb₂S₃). This innovative approach leverages the phase change properties of Sb₂S₃ to achieve reversible and tunable color filtering across the visible spectrum, offering significant potential for applications in next-generation displays and optical devices.

 

The study, published in Engineering, demonstrates how TPPCs can be dynamically tuned by inducing phase transitions in the Sb₂S₃ layer between its amorphous and crystalline states. The researchers fabricated a five-layer stack of silicon dioxide and zinc sulfide films on a silicon substrate, followed by the deposition of a 10-nm-thick Sb₂S₃ film and a 15-nm-thick silver film. By varying the thickness of the Sb₂S₃ layer and inducing phase transitions using thermal and optical activations, the team was able to achieve a shift in the resonance wavelength, resulting in distinct color changes.

 

The key to this technology lies in the unique properties of Sb₂S₃. Unlike other phase-change materials such as Ge-Sb-Te (GST), Sb₂S₃ exhibits a large index contrast and significantly lower losses in the visible spectrum, making it ideal for visible-light photonic applications. The researchers found that by switching the Sb₂S₃ layer between its amorphous and crystalline phases, the resonance wavelength could be shifted by approximately 50 nm, enabling the display of different colors.

 

The experimental setup involved using a Fourier-transform infrared (FTIR) spectrometer to measure the reflectance spectra of the TPPCs. The results showed that in the amorphous state, the resonance occurred at a wavelength of 530 nm, corresponding to a fuchsia color. Upon crystallization, the resonance shifted to 560 nm, resulting in a blue-violet color. The researchers also demonstrated the stability of the phase transitions over multiple cycles, with no observable hysteresis or degradation in performance.

 

Furthermore, the researchers explored the angular dependence of the reflectance spectra and found that the color properties remained stable for viewing angles up to 50°, with minimal color variation. This indicates that the TPPCs are insensitive to both the incidence angle and polarization, making them suitable for practical display applications.

 

By gradually increasing the thickness of the Sb₂S₃ layer, the researchers were able to achieve a complete color palette spanning the entire visible spectrum. They demonstrated this capability by fabricating a “seven-color flower” pattern, where the color of each petal could be dynamically changed by switching the Sb₂S₃ layer between its amorphous and crystalline states.

 

This study represents a significant advancement in the field of tunable photonic devices. The ability to dynamically reconfigure the color output of TPPCs without complex lithographic techniques or high energy consumption opens up new possibilities for the development of compact, high-resolution displays and optical encryption devices. The nonvolatile nature of the phase transitions in Sb₂S₃ also ensures low energy consumption, making the technology highly efficient for practical applications.

 

The paper “Optically Reconfigurable Tamm Plasmonic Photonic Crystals for Visible Spectrum,” is authored by Kuan Liu, Chuang Zheng, Shixin Gao, Xiaoming Chen, Shuang Zhang, Tun Cao. Full text of the open access paper: https://doi.org/10.1016/j.eng.2025.03.025. For more information about Engineering, visit the website at https://www.sciencedirect.com/journal/engineering.

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