On the perturbative theory of the onset of the self-focusing in the purely absorptive cw optical beam propagation
Abstract
The onset of the self-focusing of very intense CW optical beam on resonance is studied analytically using perturbational methods. The competitive effects of radially dependent nonlinear absorption of the media and the diffraction spread of the initially gaussian beam are analyzed. A radially dependent phase encoding and amplitude stripping structure are shown to evolve principally due to the nonuniform saturable absorption. The gaussian beam is reshaped into a parabolic beam. The on-axis intensity enhancement if obtained only when free space diffraction is allowed beyond the range of validity of the perturbation treatment. For parabolic beams, this axial enhancement can be obtained analytically. The radial variations of the field components, phase and wavefront, as well as the effective beam radius, show the beam reshaping and stripping effects in agreement with the numerical simulations.
- Publication:
-
Optics Communications
- Pub Date:
- May 1985
- DOI:
- 10.1016/0030-4018(85)90129-4
- Bibcode:
- 1985OptCo..54...33T
- Keywords:
-
- Continuous Wave Lasers;
- Electromagnetic Absorption;
- Nonlinear Optics;
- Optical Resonance;
- Perturbation Theory;
- Self Focusing;
- Amplitudes;
- Phase Shift;
- Radial Distribution;
- Radiant Flux Density;
- Radiation Distribution;
- Wave Diffraction;
- Lasers and Masers