Résumé
Topological insulators are generally characterized by means of integral invariants defined using cocycles over the Bloch bundle (e.g.: Chern or Stiefel characteristic classes). In the case of photonic topological insulators made of continuous media, I will show that the invariants result from the consideration of a projective algebraic curve (the spectral curve) and of the bundle of eigenvectors over it. The main result is that photonic Chern insulators do not exist in continuous media