Near-field resonances in diagnostics of multilayered media

A method of the coherent near-field sounding of multilayered dielectric structures is studied. It is based on field measurements with subwavelength probes (emitting and receiving) that are spaced in the near-field zone above the upper layer of the studied structure. It makes possible to achieve a subwavelength resolution at the control of the layers´ depth. Especially high resolution can be achieved using the resonant response. The developed approach can be used, for instance, for the monitoring of epitaxy of multilayered heterostructures using SNOM techniques.