Coherent combining of quantum cascade lasers
type: Distribution
access URL: https://pastel.hal.science/tel-00678958
format: HTML
issued: 2026-05-24T19:02:05.821050
modified: 2026-05-24T19:02:05.730581

test_moissonnage_selune
type: Agent

Coherent combining of quantum cascade lasers
type: Dataset
contact point: Organization
  fn: CCSD
keyword: physcondcm-genphysics-physicscondensed-matter-cond-matother-cond-matother
keyword: quantum-cascade-lasers
keyword: reseau-sub-longueur-donde
keyword: theses
keyword: infoeu-reposemanticsdoctoralthesis
keyword: phase-locking
keyword: mise-en-phase
keyword: coherent-combining
keyword: moyen-infrarouge
keyword: subwavelength-grating
keyword: cavite-externe
keyword: reseau-de-phase-binaire
keyword: lasers-a-cascade-quantique
keyword: mid-infrared
keyword: external-cavity
keyword: binary-phase-grating
keyword: combinaison-coherente
landing page: https://pastel.hal.science/tel-00678958
description: Powerful sources in the mid-infrared with a good beam quality are highly needed for applications such as optical countermeasures. The quantum cascade laser (QCL) is a promising solution but the maximum power achievable is not sufficient. The coherent beam combining of several QCL could lead to higher output power in the same beam and thus is an interesting solution to circumvent the current power limitation of these sources.We present a theoretical and experimental study of the coherent beam combining of QCL in a common external cavity with a beam combiner. The phase locking is totally passive since it is only based on loss minimization in the external cavity: it is a self-organization process. A general model is developed to quantify the combining efficiency and the stability that can be obtained from this method. Experimentally, the coherent combining of two QCL in a Michelson cavity is studied first and demonstrated to be efficient and stable. In order to combine more emitters, an efficient beam combiner must be designed in the mid-infrared. For that purpose, two type of gratings, a classical binary phase grating (or Dammann grating) and a more complex gradient-index structure made of local sub-wavelength patterns are designed and compared. The calculation and optimization of this sub-wavelength structure is based on the artificial media theory and is achieved with rigorous coupled wave analysis (RCWA). Finally, the coherent combining of five QCL in an external cavity with a binary phase grating is demonstrated and the scalability to the combining of more emitters is discussed. In conclusion, we present an original solution to combine coherently several QCL and thus address the power scaling issue in the mid-infrared.
identifier: NNT: 2012PA112022
issued: 2026-05-24T19:02:05.777058
language: fr
modified: 2026-05-24T19:02:05.777064