Experimental validation of the optical coherent-combining scheme

Establish experimental validation of the proposed optical-domain coherent-combining receiver, including its optically measured phase and polarization gradients, fixed-gain feedback loops, single-receiver data path, and performance under atmospheric-turbulence-induced impairments.

Background

The paper proposes an optical-domain coherent-combining architecture for multi-aperture free-space optical receivers. A passive tap of the combined field serves as a shared reference, while balanced optical detection produces branch-resolved phase and polarization alignment gradients without channel estimation, deliberate perturbation, per-branch digitization, or multiplexed probing.

The manuscript derives the combining gain, residual phase-error penalty, amplitude-mismatch penalty, and combiner-loss budget analytically, and it discusses practical limitations such as timing pre-alignment, readout-path matching, fading-dependent loop gain, the restricted polarization model, and the absence of amplitude control. However, the proposed architecture and its predicted performance have not yet been demonstrated in laboratory or field experiments.