Photon States from Propagating Complex Electromagnetic Fields
  A wavefunction for single- and many-photon states is defined by associating photons with different momenta to different spectral and polarization components of the classical, generally complex, electromagnetic field that propagates in a definite direction. By scaling each spectral component of the classical field to the square root of the photon energy, the appropriately normalized photon wavefunction acquires the desired interpretation of probability density amplitude, in contradistinction to the Riemann-Silbertsein wavefunction that can be considered as the amplitude of the photon probability energy density. 
Daniela Dragoman