The synergistic combination of the highly-ordered arrays of close-packed nano-cavities and abundant localized hot spots applied in a fiber optic probe for SERS

In this manuscript, a uniform and well-organized array of sea anemone cap cavities array (SCCA) is meticulously fabricated on the fiber end face using nanosphere lithography (NSL) and reactive ion etching (RIE) techniques. The nano-cavities possess strong light capture capabilities, greatly improving light utilization through multiple reflections. The characterization, formation process and formation mechanism of SCCA were thoroughly investigated. Compared to traditional open cavities, the theoretical maximum electromagnetic field intensity at the base of the new close-packed cavity within SCCA is 6.15 times higher, while the local electric field within the cavity is 9.7 times greater, indicating superior light trapping capability and hot spot generation. The rugged sea anemone-like structure atop SCCA fosters abundant SERS “hot spots,” further enhancing local surface plasmon resonance (LSPR), resulting in exceptional SERS performance. By utilizing 4-aminothiophene (4-ATP) as an in-situ Raman probe molecule, SCCA demonstrates high-sensitivity detection capability down to a concentration of 10 −11 M with excellent reproducibility and stable performance across multiple detections. Therefore, fiber optic SERS probes offer promising potential for high-sensitivity in-situ detection methodologies in areas such as food safety.