Active tuning of ENZ resonances in a meta-antenna through phase modulation of an optical pulse

Plasmonic nanoantennas provide new avenues to manipulate the propagation of light in materials due to their near-field enhancement and intrinsically ultrafast response time. Here, we investigate the epsilon-near-zero (ENZ) response of an L-shaped nanoantenna structure under the phenomenon of plasmonic analog of enhancement in the index of refraction. Using a quantum mechanical framework, we analyze the modulation in the response of the L-shaped nanoantenna and the emergence of the ENZ frequency region in both the linear and nonlinear plasmonic systems. Active tuning of the ENZ frequency is achieved through phase modulation of a control pulse, enabling coherent and reversible control of the effective permittivity. The analytical and three-dimensional FDTD simulation results show consistent and appreciable spectral shifts of the ENZ modes arising from coupled L-shaped nanoantenna resonances and do not rely on natural ENZ materials or bulk metamaterial layers. Moreover, our method offers a new paradigm for actively tunable plasmonic antennas as metasurfaces. These structures carry strong potential for on-chip photonic integrated circuits, enhanced field localization, slow and fast light manipulation, and emerging quantum photonic technologies. (c) 2026 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI)training, and similar technologies, are reserved.