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Reconfigurable optical devices require nanoscale control over both the material properties and the structural morphology. This study demonstrates a femtosecond laser-based imprinting technique that achieves reversible structural modulation in Ge 2 Sb 2 Te 5 (GST) phase-change nanostructures by leveraging its significant density variation during phase transition, rather than conventional dielectric tuning. We show precise control over the grating geometry, enabling polarization-selective optical responses for multiplexed information recording and reading. Applications including dual-pattern storage, multidimensional encryption, and dynamic structural color displays are realized, highlighting the versatility of this approach. Ultrafast pump–probe spectroscopy and high-resolution transmission electron microscopy reveal the microstructural dynamics during cyclic phase transitions, identifying a transition from homogeneous to heterogeneous nucleation accompanied by crystal reorientation from 001 to 011. The erasure process is complete within 50 ps, while grain refinement, lattice reorganization, and defect accumulation collectively contribute to gradual degradation in cyclic endurance. This work establishes a generalizable framework for reversible structural modulation in functional materials with potential applications in reconfigurable photonics, secure communications, and adaptive optics.
Dai et al. (Tue,) studied this question.