99% beta factor and directional coupling of quantum dots to fast light in photonic crystal waveguides determined by spectral imaging

Scarpelli, L.; Lang, B.; Masia, F.; Beggs, D. M.; Muljarov, E. A.; Young, A. B.; Oulton, R.; Kamp, M.; H�fling, S.; Schneider, C.; Langbein, W.

Abstract

© 2019 American Physical Society. Spontaneous emission from excitonic transitions in InAs/GaAs quantum dots embedded in photonic crystal waveguides at 5 K into nonguided and guided modes is determined by direct spectral imaging. This enables measurement of the absolute coupling efficiency into the guided modes, the beta factor, directly, without assumptions on decay rates used previously. Notably, we found beta factors above 90% over a wide spectral range of 40 meV in the fast light regime, reaching a maximum of (99±1)%. We measure the directional emission of the circularly polarized transitions in a magnetic field into counterpropagating guided modes, to deduce the mode circularity at the quantum dot sites. We find that points of high directionality, up to 97%, correlate with a reduced beta factor, consistent with their positions away from the mode field antinode. By comparison with calibrated finite-difference time-domain simulations, we use the emission energy, mode circularity, and beta factor to estimate the quantum dot position inside the photonic crystal waveguide unit cell.

Citation

Scarpelli, L., Lang, B., Masia, F., Beggs, D. M., Muljarov, E. A., Young, A. B., …Langbein, W. (2019). 99% beta factor and directional coupling of quantum dots to fast light in photonic crystal waveguides determined by spectral imaging. Physical Review B, 100(3), Article 035311. https://doi.org/10.1103/PhysRevB.100.035311

• Journal Article Type: Article
• Acceptance Date: Jun 19, 2019
• Online Publication Date: Jul 30, 2019
• Publication Date: Jul 30, 2019
• Deposit Date: Oct 30, 2019
• Publicly Available Date: Oct 31, 2019
• Journal: Physical Review B
• Print ISSN: 2469-9950
• Electronic ISSN: 2469-9969
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 100
• Issue: 3
• Article Number: 035311
• DOI: https://doi.org/10.1103/PhysRevB.100.035311
• Public URL: https://nottingham-repository.worktribe.com/output/2996124
• Publisher URL: https://journals.aps.org/prb/abstract/10.1103/PhysRevB.100.035311