title: Imaging Nanoscale Electromagnetic Near-Field Distributions Using Optical Forces.
abstract: We demonstrate the application of Atomic Force Microscopy (AFM) for mapping optical near-fields with nanometer resolution, limited only by the AFM probe geometry. By detecting the optical force between a gold coated AFM probe and its image dipole on a glass substrate, we profile the electric field distributions of tightly focused laser beams with different polarizations. The experimentally recorded focal force maps agree well with theoretical predictions based on a dipole-dipole interaction model. We experimentally estimate the aspect ratio of the apex of gold coated AFM probe using only optical forces. We also show that the optical force between a sharp gold coated AFM probe and a spherical gold nanoparticle of radius 15 nm, is indicative of the electric field distribution between the two interacting particles. Photo Induced Force Microscopy (PIFM) allows for background free, thermal noise limited mechanical imaging of optical phenomenon over wide range of wavelengths from Visible to RF with detection sensitivity limited only by AFM performance.
authors.affiliation: Department of Electrical Engineering and Computer Science, University of California, Irvine, CA 92697, USA.
authors.forename: Fei
authors.initials: F
authors.lastname: Huang
authors.affiliation: CaSTL Center, Department of Chemistry, University of California, Irvine, USA.
authors.forename: Venkata Ananth
authors.initials: VA
authors.lastname: Tamma
authors.affiliation: Department of Electrical Engineering and Computer Science, University of California, Irvine, CA 92697, USA.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Mardy
authors.affiliation: CaSTL Center, Department of Chemistry, University of California, Irvine, USA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Burdett
authors.affiliation: Department of Electrical Engineering and Computer Science, University of California, Irvine, CA 92697, USA.
authors.forename: H Kumar
authors.initials: HK
authors.lastname: Wickramasinghe