  The complex Faraday angle and transmission for the topological insulator
Bi2Se3 were measured in the far infrared in magnetic fields up to 8 T and
analyzed in terms of a simple Drude-Lorentz magneto-plasma dielectric model.
Bulk carriers dominate the optical response. The bulk carriers are electrons as
we determined from the sign of the Faraday angle. We obtain the bulk band edge
cyclotron mass m_cb = 0.16 +- 0.01 m_e and free electron concentration in the
10^17 range. Electron-phonon interaction effects were found to be weak.
