Near-field digital holography: a tool for plasmon phase imaging

• Published in: Nanoscale Vol. 10; no. 45; pp. 21363 - 21368
• Main Authors: Dvořák, Petr, Kvapil, Michal, Bouchal, Petr, Édes, Zoltán, Šamořil, Tomáš, Hrtoň, Martin, Ligmajer, Filip, Křápek, Vlastimil, Šikola, Tomáš
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 07.12.2018
• Subjects: Digital imaging; Electric fields; Electromagnetic fields; Far fields; Holography; Interference; Optical microscopy; Phase distribution; Selectivity
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/c8nr07438k

The knowledge of the phase distribution of the near electromagnetic field has become very important for many applications. However, its experimental observation is still technologically a very demanding task. In this work, we propose a novel method for the measurement of the phase distribution of the near electric field based on the principles of phase-shifting digital holography. In contrast to previous methods the holographic interference occurs already in the near field and the phase distribution can be determined purely from the scanning near-field optical microscopy measurements without the need for additional far-field interferometric methods. This opens a way towards on-chip phase imaging. We demonstrate the capabilities of the proposed method by reconstruction of the phase difference between interfering surface plasmon waves and by imaging the phase of a single surface plasmon wave. We also demonstrate a selectivity of the method towards individual components of the field.