Comparison of silica and sapphire fiber SERS probes fabricated by a femtosecond laser

Different types of fibers were compared for construction of reflection-based surface-enhanced Raman-scattering (SERS) fiber probes. The probes were made by direct femtosecond (fs) laser micromachining of nanometer structures on the fiber endface and subsequent chemical plating of a thin layer of silver. Rhodamine 6G solutions were used to evaluate the performance of the SERS probes. In comparison with the silica fibers, the single-crystal sapphire fiber has much lower background Raman scattering. The fs laser is found effective to fabricate high-quality sapphire fiber SERS probes for detection of weak Raman signals in a reflection configuration.