Near-field transmission matrix microscopy for mapping high-order eigenmodes of subwavelength nanostructures

Eunsung Seo, Young Ho Jin, Wonjun Choi, Yonghyeon Jo, Suyeon Lee, Kyung Deok Song, Joonmo Ahn, Q. Han Park, Myung Ki Kim, Wonshik Choi

Research output: Contribution to journalArticle

Abstract

As nanoscale photonic devices are densely integrated, multiple near-field optical eigenmodes take part in their functionalization. Inevitably, these eigenmodes are highly multiplexed in their spectra and superposed in their spatial distributions, making it extremely difficult for conventional near-field scanning optical microscopy (NSOM) to address individual eigenmodes. Here, we develop a near-field transmission matrix microscopy for mapping the high-order eigenmodes of nanostructures, which are invisible with conventional NSOM. At an excitation wavelength where multiple modes are superposed, we measure the near-field amplitude and phase maps for various far-field illumination angles, from which we construct a fully phase-referenced far- to near-field transmission matrix. By performing the singular value decomposition, we extract orthogonal near-field eigenmodes such as anti-symmetric mode and quadruple mode of multiple nano-slits whose gap size (50 nm) is smaller than the probe aperture (150 nm). Analytic model and numerical mode analysis validated the experimentally observed modes.

Original languageEnglish
Article number2575
JournalNature communications
Volume11
Issue number1
DOIs
Publication statusPublished - 2020 Dec 1

ASJC Scopus subject areas

  • Chemistry(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Physics and Astronomy(all)

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