High-power laser propagation through the atmosphere is an important topic with many scientific and practical applications, including communications, remote sensing, and directed-energy research. When a laser beam travels through the air, it does not move through a perfectly uniform medium. Instead, the atmosphere is highly dynamic: temperature changes, wind patterns, and pressure variations are constantly shifting. These fluctuations create small changes in the refractive index of air—the property that determines how light bends as it moves. Even tiny refractive-index variations can alter how a laser beam behaves as it travels.

At low power, these effects are mostly linear. In other words, the atmosphere influences the beam, but the beam does not significantly influence the atmosphere. Under these conditions, turbulence can cause familiar distortions such as scintillation (twinkling or brightness changes), beam wander (slow drifting of the beam’s position), and increased beam spread. These effects reduce the clarity or intensity of the beam at a distant target, but the physics remains relatively straightforward.

However, when the laser power is high enough, the situation becomes nonlinear. Now the beam itself can modify the air it passes through. For example, a high-power beam can locally heat the air, changing its temperature and therefore its refractive index. This means the beam reshapes the path it travels through, which in turn alters how the beam continues to propagate. These feedback effects can make high-power propagation much more complex and harder to predict.

Our research efforts focus on understanding, characterizing, and ultimately reducing these atmospheric effects. To do this, we design and build advanced laser systems capable of deliberately creating the types of nonlinear distortions we want to study, but in a controlled and measurable way. By sending these beams through outdoor atmospheric paths under different weather conditions, we can observe how the beam changes during propagation. We record the beam’s profile, spectrum, phase, and power received to build a detailed picture of how the atmosphere affects high-power lasers. This work helps us develop strategies to improve laser performance and reliability in real-world environments.