Abstract
We report a method to fabricate SERS fiber probe by femtosecond laser micromachining on a microfiber tip. Multimode optical fibers are tapered to outer diameter of 4 to 20 μm. Femtosecond laser pulses are used to form nanostructures on the cleaved endface of the microfiber tip. This endface is then activated by silver sputter coating. To confine the excitation and reflection signal within the tapered core of the microfiber tip, the probe is side-coated with silver plating. High quality SERS signal of Rhodamine 6G molecules is detected through back excitation and collection from a lead in fiber of up to several meters long. The small size of the SERS micro-probe is promising for intra-cellular or even single cell detection, while the back excitation and collection setup make it suitable for remote sensing applications.