Institute on Laser and Information Technologies
of Russian Academy of Sciences offer
 

 

From the nowadays viewpoint, the conventional types of polarization,
linear and circular, have substantial disadvantages
 At linear polarization , the parameters of interaction depend upon the direction. At circular polarization , these parameters are time averaged, not optimum either for minimum losses or for 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. In the case of radial (azimuthal) polarization the direction of the electrical vector in the plane of the beam cross section is parallel (perpendicular) to the radial direction

 
 
 

Azimuthal polarization
with minimum
losses

Circular polarization
with average parameters

because the vector of electric field rotates itself quickly

Radial polarization
with maximum absorption

 
     
Technical parameters of the laser
     
                                       
   
Wavelength
Operation mode
Output power
Mode
Polarization
Dimensions:
laser head
power supply
Life time
Shell life
     10.6 mm
Sealed off, CW
20 W
TEM01*
Radial
0.13 x 0.13 x 1 m3
0.25 x 0.15 x 0.1 m3
1000 hours
2 year 		   
   
Gas mixture can be reloaded
     
 
  The laser can be equipped with additional device. This device can change the angle between the vector of electric field and radius in all points of laser beam cross section simultaneously. In any case polarization remains axially symmetric, but using this device we can obtain as radial so azimuthal polarization and all intermediate states of polarization. In all of these situations laser beam remains the properties of "classic" Laguerre Gauss beams. Propagating in space these beams have the same intensity distribution in arbitrary units in any cross section.
 
  Laser beams with axially symmetric polarization have many unusual properties making them an excellent instrument for research works. The references following the topics are not the main or single. It is only an example.
 
  1. Such laser with low output power can be used as a generator in system generator-amplifier. Polarization properties of amplified beam will be the same.
  2. Radially polarized beams must give doubled efficiency for laser cutting metals in comparison with usual polarization of a laser beam: linear or circular.
    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.
  3. At the focusing such beams with lens the longitudinal electric field (along lens axis) appears at the lens axis in the focal spot. This reality has some interesting consequences. It is known idea to use such field for acceleration of electrons. Romea R.D. and Kimura W.D. Modeling of inverse Cherenkov laser acceleration with axicon laser beam focusing. Physical Review D, 1990, v.42, n.5, p.1807.
  4. Extremely interesting direction of investigation is so called non-diffractive (Bessel) beams. There are some schemes to synthesis such beams using radially polarized beams. Durnin J., Miceli J.J., Eberly J.H. Diffraction-Free Beams Physical Review Letters 1987, v.58, 15, p.1499-1501.
  5. Absolutely strange and unusual object is so called helical modes. They are studied bad because there are no reliable ways to generate them. We have scheme to realize the stable single generation of this very mode, using as start point radially polarized mode. Arsenyan T.I., Fedotov N.N., Kornienko L.S., Korolenko P.V., Kulyagina E.A., Petrova G.V. Laser beam with helical wavefront dislocations and their applications in the diagnostical and metrological systems. SPIE 1995, v.2713, p.453.
  6. There are many interesting experiments can be made in the field of laser beam-plasma interaction. Radially polarized beam gives maximum value of resonance absorption at the interaction with axially symmetric plasma targets. Azimuthally polarized beam does not excite any plasma oscillations leaded to charge separation in this case at all. Duderstadt J.J., Moses G.A. Inertial Confinement Fusion New York: John Wiley and Sons, 1982.
  7. Laser beam propagating through the circular hollow metallic waveguide has losses connected with absorption of radiation on the waveguide walls at large angles of incidence. Azimuthal polarization is optimum for this purpose.
    Yariv A. Propagation of optical beams in fibers. Optical Electronics 3rd ed., CBS College Publishing, New York, N.Y., p.67-66, 1985.
 
  Contact person:
     
Vladimir G.NIZIEV
    
      Address: IPLIT RAS Shatura, Moscow Region 140700 RUSSIA    
      E-mail:
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