The Advancement of Brillouin Light Scattering with the Assistance of Nanoplasmonic Structures. Enhancement and Amplification

Brillouin light scattering (BLS) is a key technique in studying magnonic systems, though its detection capabilities are often constrained by low signal-to-noise ratios. While nanoplasmonic systems can enhance BLS through near-field effects, we propose a novel approach for additional amplification. In this conceptual paper, we show how to actively supply energy to a surface common resonance (SCR) supported by a sparse layer of metal nanoparticles on a magnetic film. Proposed methods are designed to significantly amplify the efficiency of surface-enhanced Brillouin light scattering without increasing the intensity of the primary excitation. In the proposed scheme, the pump extends the propagation length of the SCR, leading directly to BLS amplification. We analyse the conditions for such amplification, with numerical estimates indicating a potential gain of more than an order of magnitude in the surface-wave amplitude. This gain far surpasses the modest increase achievable through passive enhancement alone. These findings outline a practical pathway to achieving BLS amplification in integrated magnonic platforms. The feasibility of the proposed approaches is discussed in light of recent experimental and theoretical advances in plasmonics, magneto-plasmonics, and magnonics.