Temporal coherence effects on target-based phasing of laser arrays.

Area of Science:

• Optics and Photonics
• Laser Physics
• Array Beamforming

Background:

• Fiber laser arrays are essential for high-power beam generation.
• Stimulated Brillouin scattering (SBS) can degrade laser performance.
• Temporal coherence, specifically linewidth, is a critical parameter in laser systems.

Purpose of the Study:

• To investigate the effect of temporal coherence, particularly linewidth broadening for SBS suppression, on target-based phasing of fiber laser arrays.
• To theoretically analyze radio-frequency modulated fiber laser arrays fed by broadband sources and phased on a remote target.
• To derive and discuss the expression for detector plane irradiance used in array phasing.

Main Methods:

• Theoretical analysis of a radio-frequency modulated fiber laser array.
• Derivation of the detector plane irradiance expression.
• Numerical simulations of a seven-element hexagonal array phasing on a step target with scattering surfaces.

Main Results:

• The study provides a detailed theoretical expression for detector plane irradiance.
• Simulation results validate the theoretical findings for a seven-element hexagonal array.
• The impact of coherence length on phasing accuracy over scattering surfaces is demonstrated.

Conclusions:

• Temporal coherence significantly influences the accuracy of target-based phasing in fiber laser arrays.
• Linewidth broadening, used for SBS suppression, must be considered in array phasing strategies.
• The derived irradiance expression and simulation results offer valuable insights for designing and controlling phased fiber laser arrays.