Propagation loss of line-defect photonic crystal slab waveguides

Wan Kuang, Woo Jun Kim, Adam Mock, John O'Brien

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

Photonic crystal slab waveguides are created by inserting a linear defect in two-dimensional (2-D) periodic dielectric structures of finite height. Photonic crystals provide 2-D in-plane bandgaps through which light cannot propagate, however, the fact that the waveguide modes must be index-confined in the vertical direction implies that the propagation loss is strongly dependent on the out-of-plane radiation loss. We present a fully three-dimensional finite-difference time-domain numerical model for calculating the out-of-plane radiation loss in photonic crystal slab waveguides. The propagation loss of the single-line defect waveguide in 2-D triangular lattice photonic crystals is calculated for suspended membranes, oxidized lower claddings, and deeply etched structures. The results show that low-loss waveguides are achievable for sufficiently suspended membranes and oxidized lower cladding structures. The roles of the photonic crystal in out-of-plane loss of the waveguide modes are further analyzed. It is predicted that the out-of-plane radiation loss can be reduced by shifting one side of the photonic crystal cladding by one-half period with respect to the other sides along the propagation direction.

Original languageEnglish
Pages (from-to)1183-1194
Number of pages12
JournalIEEE Journal on Selected Topics in Quantum Electronics
Volume12
Issue number6
DOIs
StatePublished - Nov 2006

Keywords

  • Finite-difference time domain (FDTD)
  • Photonic crystals
  • Propagation loss
  • Waveguides

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