Heterodyne detection signal analysis in apertureless scanning Near-field optical microscopy

C. H. Chuang, Yu-Lung Lo

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Apertureless scattering near-field optical microscopy (A-SNOM) is generally performed using a heterodyne detection technique since it provides a higher signal-to-noise (S/N) ratio than homodyne detection. Accordingly, this study constructs a robust interference-based model of the detection signal which takes account of both the tip enhancement phenomena and the tip reflective background electric field to analyze the amplitude and phase of heterodyne detection signals at different harmonics of the tip vibration frequency. The analytical results indicate that the high-order harmonic tip scattering noise decays more rapidly with a high-order Bessel function for small phase modulation depths than the near-field interaction signal. It is also shown that the signal contrast improves as the wavelength of the illuminating light source is increased or the incident angle is reduced. As compared with homodyne technique, it can be found the signal contrast is much improved in visible region in heterodyne technique. The results presented in this study provide an improved understanding of the complex signal detected in the heterodyne A-SNOM technique and suggest potential means of improving its S/N ratio such that the signal contrast of heterodyne A-SNOM can be improved.

Original languageEnglish
Title of host publication2008 Proceedings of the ASME Micro/Nanoscale Heat Transfer International Conference, MNHT 2008
Pages889-894
Number of pages6
DOIs
Publication statusPublished - 2008 Aug 20
Event1st ASME Micro/Nanoscale Heat Transfer International Conference, MNHT08 - Tainan, Taiwan
Duration: 2008 Jan 62008 Jan 9

Publication series

Name2008 Proceedings of the ASME Micro/Nanoscale Heat Transfer International Conference, MNHT 2008
VolumePART B

Other

Other1st ASME Micro/Nanoscale Heat Transfer International Conference, MNHT08
CountryTaiwan
CityTainan
Period08-01-0608-01-09

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All Science Journal Classification (ASJC) codes

  • Mechanics of Materials
  • Materials Science(all)
  • Condensed Matter Physics
  • Atomic and Molecular Physics, and Optics

Cite this

Chuang, C. H., & Lo, Y-L. (2008). Heterodyne detection signal analysis in apertureless scanning Near-field optical microscopy. In 2008 Proceedings of the ASME Micro/Nanoscale Heat Transfer International Conference, MNHT 2008 (pp. 889-894). (2008 Proceedings of the ASME Micro/Nanoscale Heat Transfer International Conference, MNHT 2008; Vol. PART B). https://doi.org/10.1115/MNHT2008-52186