  We demonstrate experimentally that single photon detection can be achieved in
micron-wide NbN bridges, with widths ranging from 0.53 $\mu$m to 5.15 $\mu$m
and for photon-wavelengths from 408 nm to 1550 nm. The microbridges are biased
with a dc current close to the experimental critical current, which is
estimated to be about 50 % of the theoretically expected depairing current.
These results offer an alternative to the standard superconducting
single-photon detectors (SSPDs), based on nanometer scale nanowires implemented
in a long meandering structure. The results are consistent with improved
theoretical modelling based on the theory of non-equilibrium superconductivity
including the vortex-assisted mechanism of initial dissipation.
