Recent experiments have shown rotation of the plane of polarization of light reflected from the surface of some superconductors.  This indicates that time reversal and certain mirror symmetries are broken in the ordered phase. The frequency of the light exceeds the electronic bandwidth. We show that in strong-coupling theory a Coulomb interaction may produce an order parameter in the unoccupied band that explains the observations. Thus we propose that the experiments have detected, for the first time,  the existence of a superconducting order parameter in an unoccupied band.

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