Spatial beam cleanup by pure Kerr processes in multimode fibers

Area of Science:

• Nonlinear optics
• Optical fiber communications
• Photonics

Background:

• Experiments show nonlinear beam quality improvement in multimode graded-index fibers.
• This improvement occurs even without significant dissipative effects like Raman scattering.

Purpose of the Study:

• To numerically simulate beam cleanup in multimode fibers using third-order Kerr nonlinearities.
• To investigate the dependence of beam cleanup on spectral/temporal disorder in the absence of dissipation.

Main Methods:

• Numerical simulations of pulse propagation.
• Modeling third-order Kerr nonlinearities in multimode fibers.
• Comparison between disordered and continuous-wave models.

Main Results:

• Beam cleanup is critically dependent on spectral/temporal disorder.
• Beam cleanup does not occur in a continuous-wave model without disorder.
• Findings align with entropy principles.

Conclusions:

• Spectral/temporal disorder is essential for nonlinear beam cleanup in multimode fibers.
• Dissipative processes are not the sole drivers of beam improvement.
• The study provides insights into the fundamental mechanisms of beam quality enhancement.