  Different densities of electromagnetic states inside a one dimensional
photonic crystal (1D PC) are studied. Hertz vector formalism is used to
calculate Green tensor inside a layered structure, semi-analytically. Based on
the obtained Green tensor, the local density of electromagnetic states (LDOS)
and the density of states (DOS) inside a 1D PC are calculated and discussed.
The Green tensor is also used to approximate the density of Bloch states inside
the 1D PC and is compared with its exact calculation based on the 1D PC
dispersion relations. Using a practical 1D PC parameters in the visible range,
the aforementioned quantities are calculated and verified with a full-wave
solver based on finite element method (FEM). The formulations and the results
are aimed to be helpful in thermal and spontaneous radiation studies.
