Saturation of the all-optical Kerr effect

Area of Science:

• Nonlinear optics
• Quantum mechanics
• Atomic physics

Background:

• The intensity dependence of the refractive index is crucial for understanding nonlinear optical phenomena.
• Previous models often simplified higher-order effects, leading to discrepancies with experimental observations.

Purpose of the Study:

• To directly compute the saturation of the refractive index's intensity dependence from ionization rates.
• To develop a comprehensive model for the saturation of the Kerr effect, incorporating all orders up to the ionization potential.
• To validate the model against experimental data and theoretical computations.

Main Methods:

• Utilizing Kramers-Kronig transforms to link ionization rates with the refractive index.
• Performing complete quantum mechanical orbital computations.
• Solving the time-dependent Schrödinger equation for higher-order terms.

Main Results:

• The linear intensity dependence and its dispersion show excellent agreement with quantum mechanical calculations.
• Higher-order terms derived from the model align with solutions from the time-dependent Schrödinger equation.
• The derived Kerr effect saturation model confirms controversial experimental findings.

Conclusions:

• The Kramers-Kronig transform provides a direct method to compute refractive index saturation.
• The developed model accurately describes the Kerr effect saturation, highlighting the significance of higher-order terms.
• The findings support the critical role of higher-order Kerr effects in phenomena like filamentation.