A scheme of generating a two mode photon added SU(2) coherent field is proposed by means of performing conditional output measurement at the beam splitter. The influences of the added photon on atomic populations and the field′s non classical properties are investigated in the system of such a field interacting with a Λ type three level atom. It is pointed out that the added photon can alter atomic populations significantly. The photon number statistical distribution of one mode tends to sub Poissonian distribution while the other tends to super Poissionian distribution, the correlation between the two modes is enhanced and nonclassical correlation degree is increased.