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Wood Anomalies and Surface-Wave Excitation with a Time Grating
Emanuele Galiffi1, Yao-Ting Wang2, Zhen Lim1
1The Blackett Laboratory, Imperial College London, SW7 2AZ London, United Kingdom.
Physical Review Letters
|October 5, 2020
Summary
Temporal modulation of material properties offers a new way to control light waves, bypassing expensive fabrication. This method enables efficient coupling of light to surface waves, providing a tunable and low-loss alternative for near-field control.
Area of Science:
- Optics and Photonics
- Materials Science
- Wave Phenomena
Background:
- Subwavelength structuring enables near-field wave control but involves complex fabrication and losses.
- Existing methods for wave confinement beyond the diffraction limit are often expensive and irreversible.
Purpose of the Study:
- To propose temporal inhomogeneities as an alternative to subwavelength structuring for near-field wave control.
- To demonstrate a tunable, lower-loss, and fast-switchable method for coupling propagating waves to evanescent modes.
Main Methods:
- Analytical and numerical modeling of temporal inhomogeneities in electromagnetic properties.
- Proposing and simulating a realistic experiment using graphene for terahertz radiation coupling to plasmons.
Main Results:
- Conceptually demonstrated the validity of temporal inhomogeneities across various material platforms and frequencies.
- Achieved efficient coupling of terahertz radiation to plasmons in graphene with unit efficiency.
- Showcased the temporal counterpart of the classical Wood anomaly.
Conclusions:
- Time modulation of material properties is a viable alternative to subwavelength structuring for near-field wave control.
- This approach offers advantages in tunability, reduced losses, and fast switching capabilities.
- Paves the way for novel devices in manipulating light and other waves.
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