This thesis presents the theory of three key elements of optical spectroscopy of the electronic excitations in bilayer graphene: angle-resolved photoemission spectroscopy (ARPES), visible range Raman spectroscopy, and far-infrared (FIR) magneto-spectroscopy. Bilayer graphene (BLG) is an atomic two-dimensional crystal consisting of two honeycomb monolayers of carbon, arranged according to Bernal…