Effective Degrees of Freedom, Orthogonality, and Capacity Limits in Optical Systems

This paper presents a structural definition of effective degrees of freedom (DOF) in optical systems, based on the number of independently resolvable modes under constraint. Independence is defined through orthogonality, with loss of orthogonality leading to collapse of independent channels and the emergence of nodal structures.

The framework provides a structural interpretation of coherence failure and capacity limits in optical systems, linking information capacity to the stability of orthogonal modes under constraint. Implications are discussed for mode-division multiplexing, orbital angular momentum systems, and coherence-limited transmission. Full methodological details are restricted pending further development.