Logo image
Back
Multi-frequency coherent emission from superstructure thermal emitters
Journal article   Open access   Peer reviewed

Multi-frequency coherent emission from superstructure thermal emitters

Guanyu Lu, Marko Tadjer, Joshua D. Caldwell and Thomas G. Folland
Applied physics letters, Vol.118(14), p.141102
04/05/2021
DOI: 10.1063/5.0048514
url
https://doi.org/10.1063/5.0048514View
Published (Version of record) Open Access

Abstract

Long-range spatial coherence can be induced in incoherent thermal emitters by embedding a periodic grating within a material supporting propagating polaritons or dielectric modes. However, only a single spatially coherent mode is supported by purely periodic thermal emitters. While various designs have been proposed for the purpose of allowing arbitrary emission profiles, the limitations associated with the partial spatial coherence of thermal emitters are not known. Here, we explore superstructure gratings (SSGs) to control the spatial and spectral properties of thermal emitters. SSGs have long-range periodicity but employ a unit cell that provides multiple Bragg vectors to interact with light. These Bragg vectors allow simultaneous launching of polaritons with different frequencies/wavevectors in a single grating, manifesting as additional spatial and spectral modes in the thermal emission profile. However, SSGs still have a well-defined period, which allows us to assess the role that finite spatial coherence plays in thermal emitters. We find that the spatial coherence length defines the maximum possible SSG period that can be used. This provides a fundamental limit on the degree of spatial coherence that can be induced in a thermal emitter and has broader implications for the use of techniques such as inverse design for structure optimization.
 Physical Sciences Physics Physics, Applied Science & Technology

Details

Metrics

7 Record Views
16 Times Cited - Web of Science
Logo image