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

Lang, Ben; Beggs, Daryl M.; Oulton, Ruth

Abstract

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 vg≈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’.

• Journal Article Type: Article
• Acceptance Date: Feb 24, 2016
• Online Publication Date: Aug 28, 2016
• Publication Date: Aug 28, 2016
• Deposit Date: May 22, 2024
• Journal: Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
• Print ISSN: 1364-503X
• Publisher: The Royal Society
• Peer Reviewed: Peer Reviewed
• Volume: 374
• Issue: 2075
• DOI: https://doi.org/10.1098/rsta.2015.0263
• Public URL: https://nottingham-repository.worktribe.com/output/34871534
• Publisher URL: https://royalsocietypublishing.org/doi/10.1098/rsta.2015.0263