  Graphene is a promising candidate for building fast and ultra-sensitive
bolometric detectors due to its weak electron-phonon coupling and low heat
capacity. In order to realize a practical graphene-based bolometer, several
important issues, including the nature of radiation response, coupling
efficiency to the radiation and the thermal conductance need to be carefully
studied. Addressing these issues, we present graphene-superconductor junctions
as a viable option to achieve efficient and sensitive bolometers, with the
superconductor contacts serving as hot electron barriers. For a
graphene-superconductor device with highly transparent interfaces, the
resistance readout in the presence of radio frequency radiation is dominated by
non-linear response. On the other hand, a graphene-superconductor tunnel device
shows dominantly bolometric response to radiation. For graphene devices
fabricated on $SiO_{2}$ substrates, we confirm recent theoretical predictions
of $T^{2}$ temperature dependence of phonon thermal conductance in the presence
of disorder in the graphene channel at low temperatures.
