Computational analysis of optical field enhancement in disordered nanoscale structures with applications to surface enhanced raman spectroscopy

In this work, the authors present a method for analyzing field enhancement in dense, disordered, semiconductor nanowire forests coated in noble metal nanoparticles using the volume integral equation. A hybrid fast solver employing the fast multipole method (FMM) and accelerated Cartesian expansions (ACE) is utilized to rapidly solve for fields in geometries which would otherwise be computationally unassailable. Using this code, nearfield maps can be generated, and comprehensive studies of field enhancement physics can be performed under a vast array of substrate conditions, and yield information that is otherwise experimentally unattainable. Preliminary field maps are presented to demonstrate the ability of our code to handle large, multiscale structures. At the conference, results will be presented exploring the influence of disorder, nanowire morphology, and material composition upon field enhancements.