Scanning near field optical microscopy of gold nano-disc arrays fabricated by electron beam lithography and their application as surface enhanced Raman scattering substrates

Gold nano-disc arrays were fabricated on glass substrates using electron beam lithography. Scanning near field optical microscopy imaging of the patterns in the near-field illumination and far-field collection (transmission and reflection) and far-field illumination with near-field collection of signal modes is reported. An analyzer was introduced before the detector to study the effect of polarization. High resolution and good contrast are obtained in reflection detection modes compared to that of transmission mode. Polarization of the beam in the transmission mode further improves the resolution and contrast of the images. Application of these arrays as surface enhanced Raman scattering substrates is demonstrated.