Refractive index measurement of silicon thin films using slab optical waveguides

Naganori Takezawa*, Isamu Kato, Shinji Nojima

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


Measurement of the real part of the refractive index (nf′) of silicon thin films using a slab optical waveguide (SOW) is discussed. Upon deposition of thin films on a SOW, the transmittance decreases with periodic oscillation owing to the multiple reflection. It is clarified from a simulation of a four-layer SOW that the period of oscillation is reduced when nf′ increases. In this paper, we discuss a method of determining the nf′ from correspondence of the minimum film thickness (d0) in which the oscillation valley appears as a calculation result of transmittance for the TE0 mode to d0 in an experiment in which the refractive index and sizes of SOW are known without considering higher modes or the TM mode. Good agreement is observed in comparison of the result of the measurement with that of the ellipsometer at a wavelength of 632.8 nm. Therefore, it can be shown that the distributions of nf′ of a-Si:H and SiN thin films at wavelengths from 400 to 800 nm are obtained in the same manner. In order to achieve higher accuracy of the measurement, a SOW with a larger refractive index is used.

Original languageEnglish
Pages (from-to)920-925
Number of pages6
JournalJapanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers
Issue number2
Publication statusPublished - 1997


  • a-Si:H
  • Optical fiber sensor
  • Refractive index
  • SiN
  • Slab optical waveguide
  • Thin film

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)
  • Engineering(all)


Dive into the research topics of 'Refractive index measurement of silicon thin films using slab optical waveguides'. Together they form a unique fingerprint.

Cite this