Continuous wave thermal loading in saturable absorbers: theory and experiment

Area of Science:

• Laser physics
• Materials science
• Optical engineering

Background:

• Continuous-wave (cw) thermal loading in solid-state saturable absorbers can significantly impact laser performance.
• Understanding thermal gradients and their effect on material properties like refractive index and saturation intensity is crucial for laser design.

Purpose of the Study:

• To develop and validate a theoretical model for investigating cw thermal loading in solid-state saturable absorbers with low thermal conductivity.
• To account for the temperature dependence of both the refractive index and fluorescence lifetime in the model.
• To provide an accurate method for determining the absorption cross-section of saturable absorbers using cw power transmission data.

Main Methods:

• Development of a theoretical model incorporating temperature-dependent refractive index and fluorescence lifetime.
• Utilizing an iterative scheme to calculate temperature distribution under pump beam illumination.
• Comparing model predictions with experimental cw transmission data from a Cr:YAG saturable absorber.

Main Results:

• The model accurately predicts temperature distribution and its effect on propagation parameters.
• Excellent agreement was achieved between calculated results and experimental cw transmission data.
• The study demonstrates the model's capability to determine the absorption cross-section of saturable absorbers.

Conclusions:

• The proposed model effectively captures the complex thermal effects in solid-state saturable absorbers.
• Accurate determination of material properties like absorption cross-section is possible through this modeling approach.
• This research contributes to improved design and characterization of saturable absorbers for laser applications.