Group velocity enhancement for guided lightwave by band-pulling effect in single-mode silicon comb photonic crystal wires

Borriboon Thubthimthong, Kazuhiro Hane

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

Photonic crystal waveguides (PCWs), which usually exhibit the slow-light effect near the band edge frequency, may in fact be used to induce higher group velocity (vg). The presence of the band edge, due to periodically carving a strip waveguide (SW) into a PCW of a comb-shape dielectric wire, results in the band-pulling effect. The band-pulling effect, which lifts the fundamental photonic band toward the band gap, not only enhances vg by reducing the effective index but also prevents the band from bending toward the light cone of the core material, leading to additional vg enhancement. The maximum PCW vg (0.43c; c = vacuum light speed) found from numerical modeling was higher than SW vg at all widths and thicknesses, except for extremely low thickness below 80 nm. We found by numerical modeling and experiments that up to 75% enhancement at the 1550 nm wavelength may be achieved in a fabricated single-mode PCW (0.38c) compared with an SW (0.21c) of the same width and thickness. The higher vg was confirmed by measuring the PCW's group index using ring resonators. The PCW propagation loss of 2.1 dB mm-1 and the bandwidth-distance product of 100 Gb/s-cm were deduced from experimental results. Our findings seemed encouraging for employing PCWs in optical interconnect applications.

Original languageEnglish
Article number055104
Pages (from-to)1-9
Number of pages9
JournalJournal of Optics (United Kingdom)
Volume17
Issue number5
DOIs
Publication statusPublished - 2015 May 1

Keywords

  • Dispersion engineering
  • Optical interconnects
  • Optical pulse propagation
  • Photonic crystal waveguide
  • Ring resonators
  • Silicon nanophotonics

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics

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