Numerical Simulation of the Whole Thermal Lensing Process with Z-Scan-Based Methods Using Gaussian Beams

Area of Science:

• Optics and Photonics
• Thermal Physics
• Materials Science

Background:

• Thermal lensing is a significant effect in laser-matter interactions.
• Existing simplified models for thermal lensing lack accuracy for precise thermo-optical coefficient determination.
• Accurate characterization of thermal effects is crucial for laser-based material processing and optical system design.

Purpose of the Study:

• To develop a comprehensive numerical simulation for the diffracted far field caused by thermal lensing.
• To derive more accurate simplified formulas for quantifying thermal phase shifts in Z-scan methods.
• To improve the reliability of temperature estimation in absorbing media using various techniques.

Main Methods:

• Numerical simulation of the entire optical and thermal system.
• Gaussian beam propagation analysis.
• Development and validation of new analytical formulas for thermal phase shift measurement.

Main Results:

• Established that current literature formulas only provide the order of magnitude for thermo-optical coefficients.
• Derived more accurate, simplified formulas for Z-scan based thermal phase shift measurements.
• Demonstrated enhanced reliability for temperature estimation in absorbing media, applicable to both time-resolved and steady-state methods.

Conclusions:

• The study provides a more accurate theoretical framework for understanding thermal lensing effects.
• The derived formulas offer practical improvements for experimental characterization of thermo-optical properties.
• The findings contribute to more precise temperature measurements and better optical system design in applications involving laser-induced thermal effects.