Fig. 4: Radiative transfer theory of a 3D graphene network.

a The theory of radiative transfer can be used to describe a disordered medium with reflective boundaries and bulk absorption and scattering processes (left). For a graphene 3D network, the former contribution is zero, while the absorptive processes can be neglected due to propagation in air (right). The remaining scattering contribution can be obtained through an expansion in the number of scattering processes. The first two contributions will take in mind the transmission of non-scattering photons and the two-scattering processes. For the incoherent experimental transmission, the only processes considered are the ones that give raise to photons propagating in the same direction of the incident radiation. b Mean free path as a function of wavelength for the sample S1, as predicted by the radiative transfer model of Eq. 5.