Plasmon-induced enhancement of ptychographic phase microscopy via sub-surface nanoaperture arrays

The invention of phase contrast microscopy revolutionized optics, enabling the visualization of highly optically transparent samples without the need for staining. The technique utilizes phase shifts within the sample and is routinely employed in the characterization of biological material and other weakly interacting objects. However, the demand for increased contrast and quantification has continued to drive research into more advanced approaches to phase imaging. Here, we demonstrate that the combination of ptychographic coherent diffractive imaging with plasmonically active metamaterials yields a massive enhancement of both the reconstructed phase and amplitude by exploiting near-field interactions at the metamaterial surface. We present results from nanofabricated samples and tissue sections with thickness ranging from 4 nm to 4 μm. In addition to enabling quantitative phase imaging of metamaterials, this approach opens the way to imaging a wide range of extremely thin or highly transparent objects previously inaccessible to optical microscopy.