Broadband enhanced-resolution imaging based on a solid-immersion square Maxwell's fish-eye lens
Phys. Rev. Applied 25, 024042 – Published 12 February, 2026
DOI: https://doi.org/10.1103/8y7b-6x12
Abstract
The resolution of conventional imaging systems is limited by the inherent diffraction limit, making the realization of enhanced-resolution imaging highly significant. This paper innovatively proposes a solid immersion square Maxwell’s fish-eye lens (solid immersion SMFEL). Through the solid immersion medium and boundary transition zone, the refractive index is ensured to vary continuously with thickness, thereby eliminating interface reflections. This results in a significant reduction of the full width at half maximum (FWHM) at the focusing position, overcoming the resolution limitations of conventional SMFEL. A series of numerical simulations were conducted to investigate the imaging performance of the solid immersion SMFEL over a wide frequency band and at different excitation points, as well as the wave-propagation characteristics at various times. The focusing effects of solid immersion SMFEL and conventional SMFEL were compared under multiple excitation sources. Subsequently, transient and steady-state analysis experiments were conducted. The proposed solid immersion SMFEL exhibits stable, wide-band, omnidirectional enhanced-resolution imaging in thin plate structures, providing a practical solution for high-resolution flexural wave-imaging applications and advancing the development of enhanced-resolution imaging technology in related fields.
