Elementary-field expansions of genuine cross-spectral density matrices.
A necessary and sufficient nonnegative definiteness condition for the cross-spectral density matrix (CDM) is derived. It is also shown that this realizability condition allows the expansion of genuine CDMs in terms of recently introduced elementary fields, namely, mean-square coherent beams, and fields with position-independent stochastic behavior. The special case of uniformly polarized electromagnetic Schell-model sources is also analyzed.
Martínez-Herrero
Rosario
R
Departamento de Optica, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, 28040 Madrid, Spain.
Mejías
Pedro M
PM