Letter pubs.acs.org/NanoLett
Far-Field Imaging for Direct Visualization of Light Interferences in GaAs Nanowires Rachel Grange,*,†,# Gerald Brönstrup,‡,# Michael Kiometzis,‡ Anton Sergeyev,† Jessica Richter,† Christian Leiterer,§ Wolfgang Fritzsche,§ Christoph Gutsche,∥ Andrey Lysov,∥ Werner Prost,∥ Franz-Josef Tegude,∥ Thomas Pertsch,† Andreas Tünnermann,†,⊥ and Silke Christiansen‡,§ †
Institute of Applied Physics, Abbe Center of Photonics, Friedrich Schiller University Jena, Max-Wien-Platz 1, 07743 Jena, Germany Max Planck Institute for the Science of Light, 91058 Erlangen, Germany § Institute of Photonic Technology, Albert-Einstein-Str. 9, 07745 Jena, Germany ∥ Solid State Electronics Department and CeNIDE, University of Duisburg-Essen, Lotharstr. 55, 47048 Duisburg, Germany ⊥ Fraunhofer Institute of Applied Optics and Precision Engineering, Albert-Einstein-Str. 7, 07745 Jena, Germany ‡
S Supporting Information *
ABSTRACT: The optical and electrical characterization of nanostructures is crucial for all applications in nanophotonics. Particularly important is the knowledge of the optical near-field distribution for the design of future photonic devices. A common method to determine optical near-fields is scanning near-field optical microscopy (SNOM) which is slow and might distort the near-field. Here, we present a technique that permits sensing indirectly the infrared near-field in GaAs nanowires via its secondharmonic generated (SHG) signal utilizing a nonscanning farfield microscope. Using an incident light of 820 nm and the very short mean free path (16 nm) of the SHG signal in GaAs, we demonstrate a fast surface sensitive imaging technique without using a SNOM. We observe periodic intensity patterns in untapered and tapered GaAs nanowires that are attributed to the fundamental mode of a guided wave modulating the Miescattered incident light. The periodicity of the interferences permits to accurately determine the nanowires’ radii by just using optical microscopy, i.e., without requiring electron microscopy. KEYWORDS: Nanowire, waveguiding, Mie scattering, second-harmonic generation, GaAs, far-field microscopy
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be detectable. The latter requirement appears not to be too much of a restriction, as most semiconducting materials (except wide bandgap semiconductors such as the group III nitrides) efficiently absorb visible light while absorption is low in the near-IR.10 Thus, the near-field at the surface of semiconductor nanostructures can be detected and imaged in an optical microscope with an accuracy only limited by the Abbe’s diffraction limit at the SHG wavelength without requiring tedious scanning and disturbing interaction of the near-field signal with a probe tip or an additional fluorescent layer. We demonstrate the feasibility of this simple and powerful optical monitoring technique in individual GaAs NWs with deep subwavelength radii (
