Exploiting Zone-Folding Induced Quasi-Bound Modes to Achieve Highly Coherent Thermal Emissions

Kaili Sun, Uriel Levy, Zhanghua Han*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Thermal emissions with high coherence, although not as high as those of lasers, still play a crucial role in many practical applications. In this work, by exploiting the geometric perturbation-induced optical lattice tripling and the associated Brillion zone folding effect, we propose and investigate thermal emissions in the mid-infrared with simultaneous high temporal and spatial coherence. In contrast with the case of period-doubling perturbation in our previous work, the steeper part of the guided mode dispersion band will be folded to the high-symmetry Γ point in the ternary grating. In this case, a specific emission wavelength corresponds to only a very small range of wavevectors. Consequently, apart from the high temporal coherence characterized by an experimental bandwidth around 30 nm, the achieved thermal emissions also feature ultrahigh spatial coherence. Calculations show that at the thermal emission wavelengths in the mid-infrared, the spatial coherence length can easily reach up to mm scale.

Original languageAmerican English
Pages (from-to)764-769
Number of pages6
JournalNano Letters
Issue number2
StatePublished - 17 Jan 2024

Bibliographical note

Publisher Copyright:
© 2024 American Chemical Society.


  • Brillion zone-folding
  • coherent thermal emitters
  • mid-infrared
  • quasi-guided mode
  • ternary grating


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