Abstract-Plasmonic Superlensing in Doped GaAs

Markus Fehrenbacher , Stephan Winnerl , Harald Schneider , Jonathan Döring , Susanne C. Kehr ,Lukas M. Eng , Yongheng Huo , Oliver G. Schmidt ,Kan Yao , Yongmin Liu , and Manfred Helm

Nano Lett., Just Accepted Manuscript

DOI: 10.1021/nl503996q

Publication Date (Web): January 13, 2015

Copyright © 2015 American Chemical Society

http://pubs.acs.org/doi/abs/10.1021/nl503996q?journalCode=nalefd

We demonstrate a semiconductor based broadband near-field superlens in the mid-infrared regime. Here, the Drude response of a highly doped n-GaAs layer induces a resonant enhancement of evanescent waves accompanied by a significantly improved spatial resolution at radiation wavelengths around lambda=20um, adjustable by changing the doping concentration. In our experiments, gold stripes below the GaAs superlens are imaged with a lambda/6 sub-wavelength resolution by an apertureless near-field optical microscope utilizing infrared radiation from a free-electron laser. The resonant behavior of the observed superlensing effect is in excellent agreement with simulations based on the Drude-Lorentz model. Our results demonstrate a rather simple superlens implementation for infrared nanospectroscopy.