Femtosecond laser ablated pyramidal fiber taper-SERS probe with laser-induced silver nanostructures

A highly sensitive pyramid-shaped SERS fiber probe (P-Probe) has been first realized by a fabrication method-femtosecond (fs) laser ablation. Using the laser-induced deposition method, silver nanostructures are grown on the pyramidal fiber with the controlled cover density by an inline power meter in real time. A reduction power ratio, the ratio of power after induction to the power before induction, is introduced to optimize the laser reduction. The P-Probe performances with different reduction power ratios show that, the induction power ratio 60% is the optimized value for the enhancement of SERS signal. The sensitivity of the fiber SERS probe is down to 10−9 M with Rhodamine 6G being target molecules. The proposed pyramid-shaped SERS fiber probe can be an alternative tool to detect the biomolecules of a single cell in biology sensing applications.