Two-way rewritable and stable photonic patterns enabled by near-infrared laser-responsive shape memory photonic crystals

There has been extensive research in the optical field resulting in the development of advanced and high-performance optical devices. Going with the current trends, development of active photonic microchips, pixel arrays-based displays, and all-optic circuits are highly desirable to meet the current technological demands. In a recently published literature, among the available photonic patterns, rewritable photonics devices have attracted significant attention of researchers owing to their less complex nature and low fabrication costs.

Alternatively, shape memory photonic crystals have been identified as promising smart photonic materials for rewritable photonic devices. However, even though shape memory photonic crystals can be deformed and recovered back to their original state when exposed to external stimuli, the resulting contact stimuli during recovery is a big challenge as it limits the application of photonic devices. Consequently, studies have shown that writing the photonic crystal materials from either way could improve processability and functionality of the photonic materials. Unfortunately, little has been reported about this phenomenon thus a great challenge towards its implementation.

To this note, Pingnan Chang, Professor Wenbin Niu, Lingcheng Qu, and Professor Shufen Zhang at the Dalian University of Technology developed a new near-infrared laser responsive shape memory photonic crystal for fabricating two-way rewritable photonic patterns. Specifically, they investigated their unique characteristics that enable fabrication of the photonic patterns by near-infrared laser writing and imprinting lithography methods. Their research work is currently published in the research journal, Journal of Materials Chemistry.

In brief, the research team initiated their study by constructing inverse shape memory photonic crystals using the template method. This was completed after introducing near-infrared converting materials into a copolymer system comprising of tetrafunctional aliphatic polyurethane acrylate and polyethylene glycol diacrylate. Next, recovery performances of the resulting shape memory photonic crystals were examined by introducing the Cu₂S nanoparticles in the near-infrared region. Eventually, they further investigated the influence of the photothermal effects and reversible plastic deformation on the photonic microstructure.

The authors observed that near-infrared laser triggering recovery and the direct pressure programming were induced by photothermal effects and reversible plastic deformation respectively. In addition, it was possible to fabricate rewritable and stable photonic patterns through remote near-infrared laser writing and imprinting lithography methods. This was attributed to high stability and reversibility of the photonic patterns. Furthermore, a new and efficient two-way rewritable capability which enabled the creation of photonic patters twice in a single erase or write cycle.

In summary, the Dalian University Scientists demonstrated the fabrication of two-way rewritable photonic patterns. The shape memory photonic crystals generally exhibited excellent stability high optical reversibility as well as the direct pressure-induced programming. To actualize their study, they investigated the two-way rewritable capability of the photonic crystals. The write and erase cycles started at two optical starts represented by brilliant colors and colorless states which was observed during reversible photonic microstructure transitions. Altogether, the study will pave the way for the development of advanced photonic devices for various application such as display, sensing and anti-counterfeiting.