Time-reversal constraint limits unidirectional photon emission in slow-light photonic crystals

Photonic crystal waveguides are known to support C-points—point-like polarization singularities with local chirality. Such points can couple with dipole-like emitters to produce highly directional emission, from which spin-photon entanglers can be built. Much is made of the promise of using slow-lig...

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Bibliographic Details
Published inPhilosophical transactions of the Royal Society of London. Series A: Mathematical, physical, and engineering sciences Vol. 374; no. 2075; pp. 1 - 11
Main Authors Lang, Ben, Beggs, Daryl M., Oulton, Ruth
Format Journal Article
LanguageEnglish
Published THE ROYAL SOCIETY 28.08.2016
Subjects
Chirality
Circular polarization
Crystals
Electric fields
Group velocity
Photonics
Photons
Standing waves
Symmetry
Waveguides
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Summary:Photonic crystal waveguides are known to support C-points—point-like polarization singularities with local chirality. Such points can couple with dipole-like emitters to produce highly directional emission, from which spin-photon entanglers can be built. Much is made of the promise of using slow-light modes to enhance this light—matter coupling. Here we explore the transition from travelling to standing waves for two different photonic crystal waveguide designs. We find that time-reversal symmetry and the reciprocal nature of light places constraints on using C-points in the slow-light regime. We observe two distinctly different mechanisms through which this condition is satisfied in the two waveguides. In the waveguide designs, we consider a modest group velocity of υg ≈ c/10 is found to be the optimum for slow-light coupling to the C-points. This article is part of the themed issue 'Unifying physics and technology in light of Maxwell's equations'.
ISSN:1364-503X
1471-2962