Stimulus-Responsive Light Coupling and Modulation with Nanofiber Waveguide Junctions
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- 作者：Ilsun Yoon ; Kanguk Kim ; Sarah E. Baker ; Daniel Heineck ; Sadik C. Esener ; Donald J. Sirbuly
- 刊名：Nano Letters
- 出版年：2012
- 出版时间：April 11, 2012
- 年：2012
- 卷：12
- 期：4
- 页码：1905-1911
- 全文大小：336K
- 年卷期：v.12,no.4(April 11, 2012)
- ISSN：1530-6992
文摘
We report a systematic study of light coupling at junctions of overlapping SnO2 nanofiber waveguides (WGs) as a function of gap separation and guided wavelength. The junctions were assembled on silica substrates using micromanipulation techniques and the gap separation was controlled by depositing thin self-assembled polyelectrolyte coatings at the fiber junctions. We demonstrate that the coupling efficiency is strongly dependent on the gap separation, showing strong fluctuations (0.1 dB/nm) in the power transfer when the separation between nanofibers changes by as little as 2 nm. Experimental results correlate well with numerical simulations using three-dimensional finite-difference time-domain techniques. To demonstrate the feasibility of using coupled nanofiber WGs to modulate light, we encased the junctions in an environment-responsive matrix and exposed the junctions to gaseous vapor. The nanofiber junctions show an 95% (or 80%) modulation of the guided 450 nm (or 510 nm) light upon interaction with the gaseous molecules. The results reveal a unique nanofiber-based sensing scheme that does not require a change in the refractive index to detect stimuli, suggesting these structures could play important roles in localized sensing devices including force-based measurements or novel chemically induced light modulators.