f[z_] := E^(-c*ComplexExpand[Abs[z], z] - c*ComplexExpand[Abs[w], w] +
I*\[Rho]*(Subscript[\[Lambda], 1] - Subscript[\[Lambda], 0])*z +
I*\[Rho]*(Subscript[\[Lambda], 2] - Subscript[\[Lambda], 1])*
w)/(Subscript[\[Sigma], 1]*z - Subscript[\[Sigma], 2]*w)