Abstract：
Near-field intensity enhancement enables laser modification of materials with feature sizes below the classical diffraction limit. Incorporating such effects into direct write techniques allows for the creation of arbitrary patterns with nanoscale resolution, but these are typically limited by the serial nature of the process, making it unsuitable for manufacturing operations.  In this presentation, we review direct-write strategies with an eye toward reducing the feature sizes and increasing the throughput.  In particular, we examine the applicability of optical trapping to position near-field focusing elements near the substrates of interest. In this method, a CW laser is used to optically trap and position an array of liquid-dispersed microspheres near a substrate using 2-d Bessel beams.  A second, pulsed laser is directed through the bead array and modifies the surface below.  By incorporating ultrafast lasers, we can take advantage of multiphoton phenomena to further improve optical confinement in these scenarios.  In the second part of the talk, we discuss further scaling of laser direct write nanopatterning to take advantage of near-field plasmonic enhancement to create transparent conduction electrodes for use in optoelectronic devices.  In these studies, we examine metallic nanowires and demonstrate the ability to confine the laser intensity only to the junction of multiple wires without damaging the delicate underlying substrate material.

Biography:
Craig B. Arnold is a Professor of Mechanical and Aerospace Engineering at Princeton University and the director of the Princeton Institute for Science and Technology of Materials.  His research ranges from basic science to applied technology aimed at developing a deeper understanding of fundamental materials synthesis and processing with interests in energy storage systems, laser materials processing and advanced optics. 
He earned his PhD. in condensed-matter physics from Harvard University, and was an NRC post-doctoral fellow prior to joining the faculty at Princeton. Previous awards include the ONR young investigator award and the NSF Career award and more recently, his work in high-speed variable focus optics won an R&D 100 award, the Laser Focus World-OSA technology innovation award, and the SPIE PRISM award for photonics innovation.