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Why can't surface plasmons in nature exist in the microwave frequency band? How does "pseudo surface plasmon" solve this problem?
In the microwave and terahertz frequency bands, real surface plasmons (SPP) cannot exist naturally, which limits the development of many technological applications. However, scientists have successfully found a solution to this dilemma through so-called "pseudo-surface plasmon" technology. This article takes an in-depth look at how this technology works and its potential applications.
Natural boundaries of surface plasmons
Surface plasmons are waves formed by coupling free electron oscillations (i.e. surface plasmons) and electromagnetic waves (i.e. polarons). These waves typically propagate along the interface of materials with positive and negative dielectric constants. However, in the microwave and terahertz frequency bands, the existence of these waves is limited due to the dispersive nature of metals. Metal behaves like a perfect electrical conductor at these frequencies, and its virtual permittivity makes SPP unable to support low-frequency modes.
Due to the characteristics of metals in the microwave and terahertz frequency bands, surface plasmons cannot exist in these frequency bands, which poses technical challenges.
Solution to false surface plasmons
In order to solve this problem, scientists have proposed the concept of Spoof Surface Plasmon Polaritons (SSPPs). Such surface plasmons are composed of artificially designed metamaterials whose structures mimic the properties of surface plasmons found in nature but operate in a lower frequency range. For example, SSPPs can be supported by a periodic lattice structure using thin metal wires, giving the SSPP dispersion behavior similar to that of real surface plasmons.
Through artificially engineered metamaterials, pseudo-surface plasmons not only overcome the limitations of nature, but also have near-perfect frequency control capabilities.
Leading the application of new technologies
The discovery of pseudo-surface plasmons and its technological applications have broad potential. For example, they can be used to reduce crosstalk in microwave integrated circuits and improve the performance of transmission lines and waveguides. In 2013, researchers successfully demonstrated matching conversion from coplanar waveguides (characteristic impedance of 50Ω) to pseudo-surface plasmon structures, which opened up a development path for a new generation of high-frequency circuits. Furthermore, integration of commercial low-noise amplifiers with pseudo-plasmonic structures has demonstrated gains of approximately 20 dB in the range from 6 to 20 GHz.
Through false surface plasmons, we can not only achieve precise frequency control, but also greatly improve the efficiency and reliability of related technologies.
Future challenges and prospects
However, the development of pseudo-surface plasmons also faces some challenges. Although this technology can extend the application range of surface plasmons, the complexity of its fabrication process and the reproducibility of its experimental data still require further study. As microwave and terahertz technologies continue to advance, pseudo-surface plasmons have the potential to play an important role in future wireless communications, imaging systems and even quantum technology.
Conclusion
The emergence of pseudo-surface plasmons not only provides an effective alternative to overcome the limitations of nature, but also provides new possibilities for the application of various new technologies. As this technology matures, we may be able to see more amazing developments in the near future. Do you also expect to see pseudo-surface plasmons play a more important role in future technology?
