End-pumped Nd:YAG laser with a longitudinal hyperbolic dopant concentration profile

Area of Science:

• Laser physics
• Materials science
• Optical engineering

Background:

• Scaling end-pumped rod lasers to high output powers is challenging due to thermal effects.
• Non-uniform dopant concentration in laser crystals leads to temperature gradients and reduced efficiency.

Purpose of the Study:

• To present an approach for scaling end-pumped rod lasers to high output powers.
• To investigate the effect of a continuously varying dopant concentration profile on thermal homogenization.

Main Methods:

• Employing a crystal with a nearly hyperbolic dopant concentration profile.
• Characterizing the crystal's dopant profile using absorption measurements.
• Calculating the on-axis temperature distribution using a Fourier-Bessel approach for the heat conduction equation.
• Considering temperature-dependent heat conductivity and heat fraction dependence on dopant concentration.

Main Results:

• Demonstrated a maximum output power of 187 W.
• Achieved an optical-to-optical efficiency of 53%.
• Observed fluorescence indicating upper laser level quenching at high dopant concentrations.

Conclusions:

• The hyperbolic dopant profile effectively homogenizes the longitudinal temperature distribution in laser crystals.
• This method enables efficient scaling of end-pumped rod lasers to high output powers.