Small footprint phase locking system for a large tiled aperture laser array.

Area of Science:

• Optics and Photonics
• Laser Physics
• Wavefront Engineering

Background:

• Coherent laser beam arrays require precise phase control for applications.
• Scaling phase sensing systems for large aperture arrays presents significant challenges.
• Existing methods for phase-locking large laser arrays are often complex and bulky.

Purpose of the Study:

• To develop and demonstrate a compact phase sensing system for controlling large cross-section coherent laser beam arrays.
• To simplify the process of phase-locking multiple laser beams in a large synthetic aperture.
• To improve the accuracy and efficiency of wavefront control in laser arrays.

Main Methods:

• A fiber bundle was used to collect and downscale (1/40) a portion of the synthetic wavefront.
• The collected wavefront was reconfigured from a 2D to a 1D array for analysis by a compact system.
• A multiple-arm servo loop stabilized the wavefront transmitted through the fiber bundle.
• Random scattering via a diffuser and an alternating projection algorithm were employed for phase-locking.

Main Results:

• The system successfully reconfigured the wavefront from a 2D to a 1D array.
• Wavefront stabilization was achieved using a multiple-arm servo loop.
• Six fiber laser beams forming an 110 mm diameter synthetic aperture were phase-locked.
• The phase-locking accuracy achieved was λ/16.

Conclusions:

• The developed phase sensing system effectively simplifies the phase-locking of large laser beam arrays.
• The fiber bundle reconfiguration technique enables the use of small-footprint analysis systems.
• The method demonstrates high accuracy (λ/16) for phase-locking synthetic apertures.