RUSSIAN ACADEMY OF SCIENCES
 
 
INSTITUTE ON LASER AND INFORMATION TECHNOLOGIES
  
 
Laboratory of Laser Diagnostics and Physics of Lasers
Head of Laboratory Prof. Vladimir G. Niziev

 Laser Beams with Radial and Azimuthal Polarization
  
 
 
       
                            Contact person  
      Researchers performing this work:
V.G. Niziev, A.V. Nesterov (Laboratory of Laser Diagnostics and Physics of Lasers, IPLIT RAS)
V.P. Yakunin (Department of Laser Optics, IPLIT RAS)
V.N. Seminogov (Laboratory of Non Linear Opyics, IPLIT RAS)
A.A.Goncharsky (Chair of Mathematical Physics of the Lomonosov Moscow State University) 		     
 
 
 
The conventional types of polarization of laser beams, linear and circular, have substantial disadvantages.
 
     
In the case of linear polarization, the parameters of the beam interaction with the matter depend upon the direction of polarization.
  At circular polarization, these parameters are time averaged, i.e., not optimum from viewpoint either of minimum losses or maximum absorption.      
 
 
 
The modes with inhomogeneous polarization are known in the laser resonator theory.
Radially or azimuthally polarized modes are the most interesting for different applications.
  
             
 

Azimuthal polarization
with minimum losses

  

Circular polarization
with average parameters

because the vector

of electric field

rotates itself quickly

 

Radial polarization
with maximum absorption

 
 
 
   
 
Special diffractive mirrors with high polarization selectivity
have been suggested to generate such modes.
 
                                                 
 
 
                                                 
   
  • Relief parameters are calculated with special program. ·
  • Chosen relief drawing gives maximum reflectivity for the mode with desirable type of polarization: radial or azimuthal. ·
  • We have special technology of production of these diffractive mirrors for high power CO2-lasers.
   
 
 
   
Diffractive mirrors for generation of radially and azimuthally polarized modes. These mirrors are used as rear mirrors inside the resonator. There are relief period, relief drawing and ray path for two mutually perpendicular polarization in the table.
   
   
Relief period
Rays' path
  
For radial polarization
  
For azimuthal polarization
      
 
   
 
 
 
Diagnostics of radially polarized radiation of 2 kW CO2-laser passed through analyzer
with "Mode Analyzer Computer" MAC-2
 
                                                 
 
   
       
 
 
     
The example of application of radially polarized beams
     
 
Normally they use circularly polarized radiation for laser cutting metals. They install folder mirror in a resonator to fix direction of linear polarization and outside a resonator quarter wavelength phase shifter is set transferring linear polarization to circular one.
 
                                                 
     
Optical scheme of a laser cutting machine with radially polarized radiation.
      
   
   
 
 
   
Advantages of using beams with radial polarization for laser cutting metals from the position of Fresnel law of radiation absorption with surface.
   
                                                 
   
   
 
 
         
List of publications with investigation results
          
   
  1. V.G.Niziev, A.V.Nesterov. Peculiarities of Laser Cutting with Polarized Radiation.
    Proceedings of the Int. Conf. Industrial Lasers & LaserApplicatoins’98 Shatura Russia
    SPIE v.3688 1998, p.169-178.
  2. V.G. Niziev, A.V. Nesterov Form and depth of cutting with polarized laser beam. Physics and Chemistry of Material Processing (in Rissian) 1999, 1, p.21-28.
  3. V.G. Niziev, A.V. Nesterov Peculiarities of Laser Cutting Metals with Laser Beam with axial symmetric polarization. Bulletin of Academy of Sciences, physical series (in Russian) 1999, 63, 10, p. 2039-2046.
  4. V.G. Niziev, A.V. Nesterov Influence of Beam Polarization on Laser Cutting Efficiency
    Journal of Physics D Appl. Phys. V.32, (1999), p. 1455-1461.
  5. A.V. Nesterov, V.G. Niziev, A.L. Sokolov, A.V. Chripunov Laser Radiation with Axial Symmetry State of Polarization. Moscow Power Institute Bulletin (in Russian) 1999, 2, p.76-79.
  6. A.V. Nesterov, V.G. Niziev, V.P. Yakunin Generation of high-power radially
    polarized beam Journal of Physics D Appl. Phys. V.32, (1999), p. 2871-2875.
  7. A.A. Goncharsky, A.V. Nesterov, V.G. Niziev, L.V. Novikova, V.P. Yakunin Optical Elements of Laser Resonator for Generation of Beam with Axial Symmetric Polarisation. Optics and Spectroscopy (in Russian) v. 88, #6, 2000.
  8. V.P. Yakunin, A.V. Nestrov, V.G. Niziev. High power CO2- laser with radially polarized beam. Proceedings of International forum on Advanced High-Power Lasers and Applications (AHPLA'99), Osaka, Japan, 1999, SPIE v.3889.
   
 
        Vladimir G. Niziev  
 
        Address: IPLIT RAS Shatura, Moscow Region 140700 RUSSIA    
       

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