Pump-induced lensing effects in diode pumped Alexandrite lasers.

Area of Science:

• Optics and Photonics
• Laser Physics
• Materials Science

Background:

• Pump-induced thermal lensing and aberrations limit power scaling in solid-state lasers.
• Maintaining high spatial TEM00 beam quality is critical for laser applications.
• Alexandrite lasers are important solid-state laser gain media.

Purpose of the Study:

• To directly measure pump-induced lensing and spherical aberration in a diode-pumped Alexandrite laser.
• To investigate these effects under both non-lasing and lasing conditions.
• To develop a theoretical model explaining the observed lensing phenomena.

Main Methods:

• Utilized a Shack-Hartmann wavefront sensor for direct wavefront measurements.
• Performed measurements on a diode-pumped Alexandrite laser system.
• Compared experimental results with theoretical models.

Main Results:

• Observed pump-induced lensing power scales sub-linearly with absorbed pump power.
• Lasing conditions reduced lensing power to 60% of the non-lasing value.
• A combined thermal and population lens model accurately predicted the experimental data.

Conclusions:

• The study provides novel insights into pump-induced lensing in Alexandrite lasers.
• A fast saturable population lens mechanism is proposed to explain self-Q-switching.
• Findings are essential for optimizing power scaling and beam quality in Alexandrite lasers.