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Microwave Photonics Systems Based on Whispering-gallery-mode Resonators
Published on: August 5, 2013
Second-harmonic whispering-gallery modes in ZnO nanotetrapod
Yong Zhang1, Huajun Zhou, S W Liu
1Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA.
Nano Letters
|April 28, 2009
Summary
Researchers observed second-harmonic (SH) whispering-gallery modes (WGMs) in zinc oxide (ZnO) nanotetrapod legs. These modes appear at various locations due to the changing diameter, with strongest signals when light polarization aligns with the ZnO crystal
Area of Science:
- Materials Science
- Optics
- Nanotechnology
Background:
- Whispering-gallery modes (WGMs) are crucial for optical resonators and sensors.
- Zinc oxide (ZnO) nanostructures offer unique optical and piezoelectric properties.
- Understanding light-matter interactions in nanostructures is key for device development.
Purpose of the Study:
- To investigate the presence and characteristics of second-harmonic (SH) WGMs in tapered ZnO nanotetrapod legs.
- To explore how the varying diameter of nanotetrapod legs influences SH WGM resonances.
- To determine the optimal conditions for exciting strong SH WGMs in these nanostructures.
Main Methods:
- Fabrication of ZnO nanotetrapods with hexagonal cross-sections.
- Tapering of the nanotetrapod legs to create a continuously changing diameter.
- Optical excitation using a fundamental laser beam and observation of second-harmonic (SH) emission.
Main Results:
- Successful observation of SH WGMs within the hexagonal cross-sections of tapered ZnO nanotetrapod legs.
- Multiple SH WGM orders resonated at different positions along the legs due to the diameter gradient.
- Maximum SH WGM intensity was achieved when the fundamental beam's polarization was parallel to the ZnO crystal's c-axis.
Conclusions:
- Tapered ZnO nanotetrapods can support multiple, spatially distinct SH WGMs.
- The polarization of the excitation light significantly impacts SH WGM strength in ZnO.
- These findings are promising for developing novel optical devices based on ZnO nanostructures.
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