  Are photons either bunched or unbunched, or are these particular cases of a
wider phenomenon? Here we will show that bunched and unbunched photons are
indeed two extreme cases of a process parameterized by a continuous parameter,
called the bunching parameter, and (mainly) we will suggest a bunching
interferometer that can be used for the construction and measurement of the
full range of values of the above bunching parameter. Finally, as an
application of the bunching parameter, we will show how the dip graph of the
HOM effect is generalized
