A hollow superconductor in its critical state with magnetic flux trapped in the hole is proposed to be used for optical signal detection and storage in a wide spectral range. The sensitivity arises from the temperature dependence of the critical magnetic field in type I superconductors or that of the volume pinning force in hard type II superconductors. With the use of the effect of low magnetic field microwave absorption we have demonstrated the flux trapping in a thin hollow disk which could serve as a basic element of planar structures for the detection of two-dimensional optical information.