Polarization time of unpolarized light

Andriy Shevchenko, Matthieu Roussey, Ari T. Friberg, Tero Setälä*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

22 Citations (Scopus)
165 Downloads (Pure)


Light produced by most natural and artificial sources is unpolarized or partially polarized. At any instant of time, however, such random light can be regarded as fully polarized, but the polarization state may vary drastically within short time intervals. This rate of change is another attribute that separates one unpolarized beam from another. Here, we study such polarization dynamics and, for the first time to our knowledge, measure the characteristic time, called the polarization time, in which the instantaneous polarization state stays essentially unaltered. The technique employs a polarization-sensitive Michelson interferometer and two-photon absorption detection valid for electromagnetic light, yielding superior femtosecond time resolution. We analyze two unpolarized light sources: amplified spontaneous emission from a fiber amplifier and a dual-wavelength laser source. The characterization of polarization dynamics can have significant applications in optical sensing, polarimetry, telecommunication, and astronomy, as well as in quantum and atom optics.

Original languageEnglish
Pages (from-to)64-70
Number of pages7
Issue number1
Publication statusPublished - 20 Jan 2017
MoE publication typeA1 Journal article-refereed


  • Coherence
  • Interference
  • Multiphoton processes
  • Polarization

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