Dresden 2009 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 40: ZnO: preparation and characterization III

HL 40.1: Talk

Thursday, March 26, 2009, 09:30–09:45, BEY 118

Experimental and numerical analysis of the waveguiding properties of ZnO nanowires — •Dongchao Hou, Jan-Peter Richters, and Tobias Voss — Institute of Solid State Physics, University of Bremen, P.O. Box 330440, D-28334 Bremen

Tapered silica fibers can be used as convenient and robust tools to couple external laser light into the waveguide modes of semiconductor nanowires. This coupling technique allows for a systematic study of the low- and high-order mode profile supported by the nanowire as well as of coupling processes between different nanowires. Using a simple flame-heated fiber-pulling method, we fabricated tapered silica fibers from standard multi-mode silica optical fibers with diameters down to below 1 micron. Optical microscopy showed that the fabricated fibers possess a high diameter uniformity and surface smoothness. With such tapered fibers, we coupled light into single ZnO nanowires and observed their waveguiding losses for different alignments between the silica fiber and the ZnO nanowires. We numerically simulated the experimentally observed waveguide properties of the nanowires using the finite-difference time-domain (FDTD) method. The dependence of the coupling efficiency on the diameters, the overlap length and separation was investigated. We found a maximum coupling efficiency of up to 0.8 for silica and ZnO nanowires with typical diameters used in experiment. The results show that silica tapered fibers are well suited to study the waveguiding properties of semiconductor nanowires which are of importance for the design and optimization of nanowires lasers, sub-wavelength waveguides and sensors.