Three-dimensional simulation of beam propagation and heat transfer in static gas Cs DPALs using wave optics and fluid dynamics models

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


Analysis of beam propagation, kinetic and fluid dynamic processes in Cs diode pumped alkali lasers (DPALs), using wave optics model and gasdynamic code, is reported. The analysis is based on a three-dimensional, time-dependent computational fluid dynamics (3D CFD) model. The Navier-Stokes equations for momentum, heat and mass transfer are solved by a commercial Ansys FLUENT solver based on the finite volume discretization technique. The CFD code which solves the gas conservation equations includes effects of natural convection and temperature diffusion of the species in the DPAL mixture. The DPAL kinetic processes in the Cs/He/C2H6 gas mixture dealt with in this paper involve the three lowest energy levels of Cs, (1) 62S1/2, (2) 62P1/2 and (3) 62P3/2. The kinetic processes include absorption due to the 1→3 D2 transition followed by relaxation the 3 to 2 fine structure levels and stimulated emission due to the 2→1 D1 transition. Collisional quenching of levels 2 and 3 and spontaneous emission from these levels are also considered. The gas flow conservation equations are coupled to fast-Fourier-transform algorithm for transverse mode propagation to obtain a solution of the scalar paraxial propagation equation for the laser beam. The wave propagation equation is solved by the split-step beam propagation method where the gain and refractive index in the DPAL medium affect the wave amplitude and phase. Using the CFD and beam propagation models, the gas flow pattern and spatial distributions of the pump and laser intensities in the resonator were calculated for end-pumped Cs DPAL. The laser power, DPAL medium temperature and the laser beam quality were calculated as a function of pump power. The results of the theoretical model for laser power were compared to experimental results of Cs DPAL.

Original languageEnglish
Title of host publicationHigh-Power Lasers
Subtitle of host publicationTechnology and Systems, Platforms, and Effects
EditorsHarro Ackermann, Willy L. Bohn, David H. Titterton
ISBN (Electronic)9781510613362
StatePublished - 5 Dec 2017
EventHigh-Power Lasers: Technology and Systems, Platforms, and Effects 2017 - Warsaw, Poland
Duration: 11 Sep 201714 Sep 2017

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceHigh-Power Lasers: Technology and Systems, Platforms, and Effects 2017


  • Atomic gas lasers
  • Beam propagation
  • Buoyancy
  • Diode pumped lasers
  • Laser theory
  • Thermal effects

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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