Simplified expression for transverse mode instability threshold in high power fiber lasers

Area of Science:

• Optics and Photonics
• Laser Physics
• Materials Science

Background:

• Transverse Mode Instability (TMI) is a critical limiting factor in high-power fiber lasers.
• Existing models for TMI threshold power lack clarity on the influence of various parameters.
• Accurate prediction of TMI is essential for designing robust and scalable fiber laser systems.

Purpose of the Study:

• To derive a novel analytical expression for the transverse mode instability (TMI) threshold power.
• To elucidate the impact of fiber and system parameters on TMI threshold power.
• To provide a tool for optimizing fiber laser design and mitigating TMI.

Main Methods:

• Solving the heat conduction equation and nonlinear coupling equation.
• Utilizing Gaussian functions to fit the fundamental mode.
• Developing an analytical expression for TMI threshold power.

Main Results:

• The proposed analytical expression accurately predicts TMI threshold power, consistent with experimental and simulation data.
• The derived formula explicitly demonstrates the influence of key fiber and system parameters on TMI.
• Investigated the effect of specific parameters on TMI threshold and power scaling.

Conclusions:

• The new analytical expression offers a clear understanding of factors influencing TMI threshold power.
• This work provides valuable insights for the design of high-power fiber lasers.
• The findings contribute to effective TMI mitigation strategies in fiber laser technology.