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Far-field imaging for direct visualization of light interferences in GaAs nanowires

: Grange, Rachel; Brönstrup, Gerald; Kiometzis, Michael; Sergeyev, Anton; Richter, Jessica; Leiterer, Christian; Fritzsche, Wolfgang; Gutsche, Christoph; Lysov, Andrey; Prost, Werner; Tegude, Franz-Josef; Pertsch, Thomas; Tünnermann, Andreas; Christiansen, Silke


Nano Letters 12 (2012), No.10, pp.5412-5417
ISSN: 1530-6984
ISSN: 1530-6992
Journal Article
Fraunhofer IOF ()
nanowire; waveguiding; Mie scattering; second-harmonic generation; GaAs; far-field microscopy

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 second-harmonic generated (SHG) signal utilizing a nonscanning far-field 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 Mie-scattered 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.