Novel technologies to micro and nanostructure highly nonplanar optical fibers: from the micro to the sub-50 nm regime

Recent advancements in optogenetics and brain interfacing technologies have significantly improved neuroscience research. However, developing user-friendly and efficient probes with high spatial and temporal resolution and specificity remains a challenge. Tapered Optical Fibers (TOFs) have emerged as an intriguing solution due to their unique properties. This work reviews the strategies developed to enable precise definitions of light delivery and collection sites along the TOF axis, incorporating additional functionalities such as electrical recording sites or exploiting alternative light-matter interactions for label-free applications. The latest progresses in TOF micro and nanostructuring are categorized based on these objectives, highlighting the benefits and limitations of each approach. This manuscript aims at providing a comprehensive overview of recent advancements in TOF micro and nanostructuring.