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Directional coupling in channel plasmon-polariton waveguides
Vladimir A Zenin1, Valentyn S Volkov, Zhanghua Han
1Institute of Technology and Innovation, University of Southern Denmark, Niels Bohrs Allé 1, DK-5230 Odense M, Denmark. zenin@iti.sdu.dk
Optics Express
|March 16, 2012
Summary
Directional couplers using channel plasmon-polariton waveguides demonstrate strong optical power splitting at small separations. Coupling efficiency decreases significantly as waveguide separation increases, vanishing at 2 µm.
Area of Science:
- Plasmonics
- Nanophotonics
- Waveguide technology
Background:
- Directional couplers (DCs) are fundamental components in integrated optics.
- Channel plasmon-polariton waveguides (CPPWs) offer subwavelength confinement for optical signals.
Purpose of the Study:
- To investigate the coupling characteristics of DCs formed by CPPWs.
- To evaluate the impact of waveguide separation on power splitting.
Main Methods:
- Fabrication of DCs with parallel CPPWs using focused ion-beam (FIB) milling.
- Characterization at telecom wavelengths (1425-1630 nm) using near-field optical microscopy.
- Comparison with finite-element method (COMSOL) simulations.
Main Results:
- Strong coupling and near-equal power splitting observed for CPPW separations of 0.08 and 0.25 µm.
- Coupling deteriorates with increasing separation, becoming negligible at 2 µm.
- Experimental results show good agreement with simulation data.
Conclusions:
- CPPW-based DCs enable efficient power splitting at nanoscale separations.
- Waveguide separation is a critical parameter for controlling coupling in CPPW directional couplers.
- FIB fabrication is a viable technique for creating complex plasmonic waveguide devices.
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