Studies on the diffraction image of a thermal lens

Area of Science:

• Optics and Photonics
• Laser Physics
• Diffraction Theory

Background:

• Thermal lenses are crucial optical components in laser systems.
• Accurate modeling of laser light propagation through thermal lenses is essential for precise detection.
• Existing approximate models may not fully capture the behavior of strong thermal lenses or aberrations.

Purpose of the Study:

• To calculate the laser light intensity distribution behind a thermal lens.
• To compare numerical results with approximate models for laser light detection.
• To develop and validate a new approximate solution for strong thermal lenses.

Main Methods:

• Numerical quadrature of the Fresnel diffraction integral was employed.
• Comparison with existing approximate models for laser light detection.
• Analysis of the transverse profile and intensity distribution for weak and strong thermal lenses.

Main Results:

• A new approximate solution for the diffraction integral applicable to strong thermal lenses was developed.
• The aberrant nature of thermal lenses significantly impacts intensity distribution, even for weak lenses.
• A simple formula for the most intense interference ring position was derived, showing linear dependence on thermal lens strength.

Conclusions:

• Accurate laser light detection necessitates considering thermal lens aberrations.
• The new approximate solution enhances the applicability of diffraction integral models to strong thermal lenses.
• Spherical aberration affects central intensity, regardless of the observed transverse profile.