Programmable flexible self-assembled micro/nano gratings: from fabrication strategies to tunable photonic functions

This review explores the development of programmable flexible self-assembled micro/nano gratings, focusing on their fabrication strategies, dynamic modulation mechanisms, and emerging photonic applications. Emphasis is placed on strain-driven self-assembly techniques using soft elastic substrates (e.g., PDMS), template-based replication methods, and functional composite integration for enhanced optomechanical performance. Key applications include tunable diffraction devices, strain/physical/chemical sensors, adaptive optical systems, and energy harvesting devices. A critical discussion is provided on material composition, structural design principles, and scalability challenges in grating fabrication. This review aims to consolidate recent advances in flexible grating technology, demonstrating how tailored micro/nano structures enable dynamic photonic functionality. Future directions and unresolved challenges in stability, integration, and multi-field coupling are outlined to guide next-generation programmable photonic systems.