Abstract
Almost twenty years ago, light was slowed down to less than 10-7 of its vacuum speed in a cloud of ultracold atoms of sodium. Upon a sudden turn-off of the coupling laser, a slow light pulse can be imprinted on cold atoms such that it can be read out and converted into a photon again. In this process, the light is stopped by absorbing it and storing its shape within the atomic ensemble. Alternatively, the light can be stopped at the band edge in photonic-crystal waveguides, where the group speed vanishes. Here, we extend the phenomenon of stopped light to the new field of parity-time (PT) symmetric systems. We show that zero group speed in PT symmetric optical waveguides can be achieved if the system is prepared at an exceptional point, where two optical modes coalesce. This effect can be tuned for optical pulses in a wide range of frequencies and bandwidths, as we demonstrate in a system of coupled waveguides with gain and loss.
Original language | English |
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Article number | 013901 |
Journal | Physical Review Letters |
Volume | 120 |
Issue number | 1 |
DOIs | |
State | Published - 5 Jan 2018 |
Externally published | Yes |
Bibliographical note
Publisher Copyright:© 2018 American Physical Society.
Funding
The authors are grateful to Moti Segev and Meir Orenstein for most helpful discussions. A. A. M. is supported by the CNPq Grant No. 302351/2015-9. N. M. acknowledges the financial support of I-Core: The Israeli Excellence Center “Circle of Light,” and of the Israel Science Foundation Grant No. 1530/15.
Funders | Funder number |
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Conselho Nacional de Desenvolvimento Científico e Tecnológico | 302351/2015-9 |
Israel Science Foundation | 1530/15 |