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Boosting Optical Nanocavity Coupling by Retardation Matching to Dark Modes
Rohit Chikkaraddy1, Junyang Huang1, Dean Kos1
1NanoPhotonics Centre, Cavendish Laboratory, Department of Physics, University of Cambridge, JJ Thompson Avenue, CambridgeCB3 0HE, U.K.
ACS Photonics
|February 23, 2023
Summary
Controlling the refractive index surrounding plasmonic nanoantennas enables efficient frequency tuning and enhanced light coupling. This method activates dark modes, improving functionalities without complex antenna shape adjustments.
Area of Science:
- Nanophotonics
- Plasmonics
- Optical Engineering
Background:
- Plasmonic nanoantennas concentrate light to nanometer scales, creating intense field enhancements.
- Achieving tight optical confinements (0.5-5 nm) in plasmonic gaps is highly sensitive to gap spacing, refractive index, and facet width.
- Tuning optical properties by altering antenna shape is challenging due to these sensitivities.
Purpose of the Study:
- To investigate an alternative method for tuning plasmonic nanoantenna properties.
- To enhance frequency tuning and in-/output coupling efficiency in plasmonic systems.
- To explore the activation of dark modes for improved functionalities.
Main Methods:
- Investigated the effect of the surrounding refractive index on plasmonic nanoantenna optical properties.
- Utilized retardation matching principles to analyze light coupling.
- Analyzed the conditions under which dark modes become optically active.
Main Results:
- Controlling the surrounding refractive index offers an effective way to tune antenna properties.
- Retardation matching through refractive index control enhances in-/output coupling.
- Dark modes can be activated by manipulating the surrounding refractive index, leading to improved performance.
Conclusions:
- The surrounding refractive index is a critical and tunable parameter for plasmonic nanoantennas.
- Manipulating the refractive index provides a simpler and more effective route for tuning and enhancing plasmonic devices compared to shape modification.
- This approach broadens the applicability of plasmonic nanoantennas by enabling efficient control over their optical responses and functionalities.
