Band filling effects on coherence lengths and penetration depth in the two-orbital negative-U Hubbard model of superconductivity

► The two-orbital superconducting state is modelled by negative-U Hubbard correlations. ► The critical temperature is governed by intra-orbital interactions and band filling. ► Two-component superconductivity coherence lengths and penetration depth are studied. ► Critical and non-critical coherence lengths are compared to the penetration depth. ► The proximity effect is reflected in temperature behaviour of characteristic lengths.