High-order LG modes in off-axis pumped solid-state lasers with the thermal lens effect

Area of Science:

• Laser Physics
• Optics
• Solid-State Lasers

Background:

• The thermal lens effect is a critical factor influencing laser beam characteristics.
• Laguerre-Gauss (LG) modes are important for various optical applications.
• Off-axis pumping in solid-state lasers can introduce unique optical phenomena.

Purpose of the Study:

• To investigate the impact of the thermal lens effect on Laguerre-Gauss (LG) modes.
• To analyze mode hopping phenomena in off-axis pumped solid-state lasers.
• To identify methods for stabilizing LG modes and achieving high-quality laser output.

Main Methods:

• Direct generation of LG01-LG07 laser modes using off-axis pumping.
• Experimental observation and analysis of mode characteristics under varying crystal temperatures.
• Adjustment of off-axis pumping parameters to mitigate thermal effects.

Main Results:

• The thermal lens effect induces mode hopping in LG modes as crystal temperature increases.
• Mode hopping progresses from single to mixed modes and then to lower-order LG modes.
• A negative correlation was observed between crystal heat sink temperature and mode order during hopping.
• Adjusting off-axis pumping effectively resolved mode hopping, stabilizing the LG07 beam.
• Stable output of 1.52 W for the LG07 beam was achieved at 6.5 W pump power.

Conclusions:

• The thermal lens effect significantly influences LG mode stability in off-axis pumped lasers.
• Off-axis pumping parameters are crucial for controlling and stabilizing LG modes.
• The study demonstrates a method to overcome thermal lensing-induced mode hopping for stable, high-order LG mode generation.