Even though gold nanorod doped dielectrics have been widely used for optical laser writing and patterning there has been no attempt to study the dynamic range of these nanocomposites, let alone exploring ways to improve this property. Here we study the dynamic range of a gold nanorod doped polyvinyl alcohol film for various laser spot sizes at two different laser pulse repetition rates and show that when a high repetition rate laser source is employed the dynamic range of the nanocomposite is severely limited due to accumulative heating inside the focal volume. This problem could be solved by silica-coating the nanorods inside the polymer matrix. This method does not compromise the high repetition rate of the laser writing source and yet retains the attractive flexible properties of the polymer matrix. The silica-coated gold nanorod doped polymer nanocomposite could be an attractive medium for future high-speed, high repetition rate pulsed laser writing and patterning applications.

Electroless metal deposition is a simple and convenient technique to fabricate metallic films and to provide isotropic metal functionalization of 3D structures with complex geometries. In this work, we describe the synthesis of silver coatings by means of a modified Tollens reaction and their use as optical coating. The chemical composition of the metallization bath is here addressed to optimize the metal coating deposition. The synthesis parameters have been tailored in order to deposit very smooth films which were characterized by scanning electron microscopy, atomic force microscopy, and optical spectroscopy. 2D diffraction gratings and sinusoidal plasmonic gratings were produced with the proposed method. Optical characterization confirmed the plasmonic activities of the resultant structures, proving the efficiency of the described method for optical applications. Thermal annealing was found to improve the surface roughness of the coating and therefore the optical properties of the plasmonic gratings

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Nanometric plasmonic slits with stepped corrugations have been designed and fabricated to achieve plasmonic focusing and focal depth modulation. A scanning near-field optical microscope is employed to directly visualize the transmitted light from the slits. The near-field and far-field two-dimensional images taken at different planes parallel to the slit surface unambiguously demonstrated the focusing effect of the nanoslits. Furthermore, by forming stepped corrugations with either a concave or a convex profile on both sides of the slits, the phase of the transmitted beam can be effectively manipulated, thus allowing an accurate tuning of the focal depth.