Challenges and research opportunities in silicon-based subwavelength grating technologies

Silicon-based subwavelength gratings (SWG) have become important building blocks in integrated photonics because their engineered effective refractive index enables precise tailoring of optical confinement, dispersion, polarization, and light–matter interaction. However, significant challenges remain in the development of SWGs, limiting their cross-disciplinary applications, commercialization, and large-scale manufacturing. Unlike previous reviews focused primarily on SWG physics and device performance, this article examines the pathway from laboratory demonstration to scalable manufacturing and commercialization. We connect the physical sensitivities of SWG structures with experimental validation, design-for-manufacturability, process monitoring, photonic design kit development, testing, and packaging. We also propose a minimum reporting set and present roadmaps for benchmarking, foundry qualification, design automation, and commercial deployment. This review identifies the developments needed to transform SWGs from individually optimized research devices into reproducible and manufacturable photonic components.