Polarization-independent unidirectional light transmission by an annular photonic crystal prism

Melike Behiye Yucel, Ahmet Cicek, Bulent Ulug

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)

Abstract

Unidirectional transmission of light irrespective of its polarization by a two-dimensional annular photonic crystal in the form of a right prism is numerically demonstrated. Band structure of the crystal obtained through the plane-wave expansion method reveals a directional band gap along a principal axis, leading to prohibition of wave transmission in the reverse direction. In the forward direction, however, transmission of waves is facilitated by circumventing the directional band gap due to altered surface orientation. Polarization-independent unidirectional light transmission is demonstrated through finite-difference time-domain simulations. Unidirectional operation is enhanced and the polarization independence is established through the introduction of an anti-reflection coating layer, which increases the forward transmittances for both polarizations up to 0.44, such that a contrast ratio of 0.96 is attained at a free-space wavelength of 1.55 μm. Although polarization independence deteriorates, unidirectionality is preserved between 1.45 μm and 1.60 μm, provided that the angle of incidence remains between -5 and +5. Device performance is also influenced by the transverse source size, where leakage in the reverse direction may be suffered if the source width is beyond a critical value.

Original languageEnglish
Pages (from-to)270-278
Number of pages9
JournalPhotonics and Nanostructures - Fundamentals and Applications
Volume11
Issue number3
DOIs
Publication statusPublished - Aug 2013
Externally publishedYes

Keywords

  • Annular photonic crystal
  • Directional band gap
  • Polarization independence
  • Unidirectional light transmission

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