D.V. Kazantsev†a,b,
E.A. Kazantseva‡c aLebedev Physical Institute, Russian Academy of Sciences, Leninsky prosp. 53, Moscow, 119991, Russian Federation bHSE University, ul. Myasnitskaya 20, Moscow, 101000, Russian Federation cMoscow Technological University, prosp. Vernadskogo 78, Moscow, 119454, Russian Federation
Recent advances in apertureless scanning near-field optical microscopy (ASNOM) operating in the scattering-type scanning mode (sSNOM) are reviewed. Principles of ASNOM operation, technical solutions, distortions, and interference types characteristic of sSNOM-based instruments and theoretical models underlying the sSNOM technique are discussed. Methods for detecting the probing field effect on a sample under a tip (for example, thermal expansion) have been created; numerous studies have been conducted in the THz and microwave ranges. Material-contrast surface imaging is being successfully developed and nanoscale surface areas are being explored using spectroscopic methods. Progress in visualizing standing and running plasmon- and phonon-polariton waves over the surface of solid and 2D objects, including van-der-Waals materials and graphene, are presented. Hybridization of polariton states due to the interaction of carriers in a thin 2D object with those in a substrate has been discovered. Spatial resolution of ASNOM devices (1—20 nm) during the last 5—8 years has virtually remained the same.