Overcoming losses in superlenses with synthetic waves of complex frequency

Abstract

<p>Superlenses made of plasmonic materials and metamaterials can image features at the subdiffraction<br>scale. However, intrinsic losses impose a serious restriction on imaging resolution, a problem that has<br>hindered widespread applications of superlenses. Optical waves of complex frequency that exhibit a<br>temporally attenuating behavior have been proposed to offset the intrinsic losses in superlenses through<br>the introduction of virtual gain, but experimental realization has been lacking because of the difficulty of<br>imaging measurements with temporal decay. In this work, we present a multifrequency approach to<br>constructing synthetic excitation waves of complex frequency based on measurements at real<br>frequencies. This approach allows us to implement virtual gain experimentally and observe<br>deep-subwavelength images. Our work offers a practical solution to overcome the intrinsic losses<br>of plasmonic systems for imaging and sensing applications.<br></p>