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Optical Review

, Volume 26, Issue 6, pp 644–651 | Cite as

Interference phenomenon on the complex degree of coherence

  • Nori Shibata
  • Kimitaka WatanabeEmail author
  • Masaharu Ohashi
  • Ryo Maruyama
  • Nobuo Kuwaki
  • Kazuhiko Aikawa
Regular Paper
  • 76 Downloads

Abstract

A two-beam interferometer (TBI) with a two-mode fiber (TMF) as a dispersive medium in one arm and air in the other provides evidence of interference related to the complex degree of coherence \(\gamma \). A TMF with a low differential group delay (DGD) is used to measure the interference effect, since the overlapping of each individual mode at the output of a TMF is easily and artificially created in the vicinity of the zero DGD wavelength. When \(\gamma _{01}\) and \(\gamma _{11}\), respectively, are the complex degrees of coherence for the interferences between the \(\hbox {LP}_{01}\) and \(\hbox {LP}_{11}\) modes propagating through a TMF and a wave traversing air-path, the interference effect can be verified using the relationship \(|\gamma |^2=|\gamma _{01}+\gamma _{11}|^2\). The experiments are carried out using a low coherence source and three kinds of TMFs with zero DGD wavelengths around 1550 nm. It is clearly observed that \(|\gamma |^2\)-response waveforms have oscillatory structures due to the interference between \(\gamma _{01}\) and \(\gamma _{11}\). A \(|\gamma |^2\)-response measurement employing the TBI reveals that the theoretically obtained \(|\gamma |^2\)-curves well reflect \(|\gamma |^2\)-curve obtained experimentally for a temporally overlapped wave composed of the two modes. To the best of our knowledge, this is the first experimental demonstration of the interference between complex degrees of coherence.

Keywords

Fiber optics Interference Coherence 

Notes

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Copyright information

© The Optical Society of Japan 2019

Authors and Affiliations

  1. 1.Nihon UniversityKoriyamaJapan
  2. 2.Osaka Prefecture UniversitySakaiJapan
  3. 3.Fujikura LtdSakuraJapan
  4. 4.Fujikura High Opt Co., LtdTokyoJapan

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