Surface enhanced Raman spectroscopy by interfered femtosecond laser created nanostructures

A type of surface enhanced Raman spectroscopy (SERS) by interfered femtosecond laser created nanostructures on Cu metal is presented. It is found out that finer and more uniform nanostructures (with an average feature size 100 nm or smaller) can be created on Cu metal by interfered femtosecond illumination with a phase mask. Significantly enhanced Raman signal (with an enhancement factor around 863) can be realized by using the nanostructured Cu substrate created by the interfered femtosecond laser illumination. The experimentally measured enhancement factor agrees relatively well with the theoretical analyses. Since the nanostructures can be inscribed in real time and at remote locations by the femtosecond laser inscription, the proposed SERS can be particularly useful for the standoff detection of chemicals.