Optical depth for the γ + γ → e⁺ + e⁻ process, calculated in the nonlocal inhomogeneous jet model for the parameters reported in Table 1 (upper panel). Top: optical depth as a function of the γ-ray photon energy. The opacity threshold (τ_{γ − γ} = 1) is shown with the dashed line. Bottom: optical depth for the γ + γ → e⁺ + e⁻ process as a function of distance from the jet base for a few selected energies of γ-ray photons: ϵ_γ = 1 TeV (dashed line), ϵ_γ = 3 TeV (dot-dashed line), and ϵ_γ = 10 TeV (solid line; bottom panel).