• Open Access

Theory of the Coherence of Topological Lasers

Ivan Amelio and Iacopo Carusotto
Phys. Rev. X 10, 041060 – Published 24 December 2020
PDFHTMLExport Citation

Abstract

We present a theoretical study of the temporal and spatial coherence properties of a topological laser device built by including saturable gain on the edge sites of a Harper-Hofstadter lattice for photons. For small enough lattices, the Bogoliubov analysis applies, and the coherence time is almost determined by the total number of photons in the device in agreement with the standard Schawlow-Townes phase diffusion. In larger lattices, looking at the lasing edge mode in the comoving frame of its chiral motion, the spatiotemporal correlations of long-wavelength fluctuations display a Kardar-Parisi-Zhang (KPZ) scaling. Still, at very long times, when the finite size of the device starts to matter, the functional form of the temporal decay of coherence changes from the KPZ stretched exponential to a Schawlow-Townes-like exponential, while the nonlinear dynamics of KPZ fluctuations remains visible as a broadened linewidth as compared to the Bogoliubov-Schawlow-Townes prediction. While we establish the above behaviors also for nontopological 1D laser arrays, the crucial role of topology in protecting the coherence from static disorder is finally highlighted: Our numerical calculations suggest the dramatically reinforced coherence properties of topological lasers compared to corresponding nontopological devices. These results open exciting possibilities for both fundamental studies of nonequilibrium statistical mechanics and concrete applications to laser devices.

  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
2 More
  • Received 28 February 2020
  • Revised 26 August 2020
  • Accepted 22 October 2020

DOI:https://doi.org/10.1103/PhysRevX.10.041060

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

Published by the American Physical Society

Physics Subject Headings (PhySH)

Statistical Physics & ThermodynamicsNonlinear DynamicsCondensed Matter, Materials & Applied Physics

Authors & Affiliations

Ivan Amelio and Iacopo Carusotto

  • INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, 38123 Povo, Italy

Popular Summary

Lasers are a fundamental tool in modern science that are getting a boost from the burgeoning field of topological photonics, which aims to develop light-carrying materials that are largely impervious to structural imperfections. Recently, researchers developed a topological laser device with promising power efficiency and robustness to fabrication faults. Here, for the first time, we theoretically study the coherence properties of this class of devices and show that the new laser’s coherence can compete with traditional ones and that the device displays improved resilience to the defects of the optical lattice.

In particular, we consider a 2D photonic lattice with a synthetic magnetic field. Lasing is given by the competition of gains and losses along the edge of the system; topology ensures that the lasing mode stays localized on the boundary of the system and propagates in one direction. This propagation suggests mapping the 2D system to a 1D laser, for which phase fluctuations display universal behavior. Using this mapping, we study in detail the ultimate limits to the spectral width of the laser emission, identifying a crossover between the linear and nonlinear regimes in the phase diffusion.

The next steps will entail characterization of topological lasing when the dynamics of the amplifying medium cannot be neglected, as well as the possibility of simulating other theoretical physics models.

Key Image

Article Text

Click to Expand

Supplemental Material

Click to Expand

References

Click to Expand
Issue

Vol. 10, Iss. 4 — October - December 2020

Subject Areas
Reuse & Permissions
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review X

Reuse & Permissions

It is not necessary to obtain permission to reuse this article or its components as it is available under the terms of the Creative Commons Attribution 4.0 International license. This license permits unrestricted use, distribution, and reproduction in any medium, provided attribution to the author(s) and the published article's title, journal citation, and DOI are maintained. Please note that some figures may have been included with permission from other third parties. It is your responsibility to obtain the proper permission from the rights holder directly for these figures.

×

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×