  The generation of fully coherent broadband mid-infrared (MIR) supercontinuum
(SC) from 2.3 um to 8.3 um is demonstrated by using a 4.1 um pump and an As2Se3
photonic crystal fiber (PCF).By introducing the random quantum noise and the
power instability on the input pulse and by numerically implementing the
Young,s double slits experiment, we examine the coherence properties across the
SC spectrum. It is found that the coherence of this MIR SC source depends
strongly on the input pulse duration, the peak power, the power stability, and
the zero-dispersion wavelength (ZDW) of the As2Se3 PCF.The optimal conditions
for the MIR SC with a maximal coherent bandwidth are identified.
