New Phenomena in JosephsonSINISJunctions

We analyze the dc and ac Josephson effects in $S_a{\mathrm{INIS}}_b$ junctions in which an additional bias current flows in the $N$ layer. The case of low temperatures and voltages $(eV,T\ll \Delta )$ is considered in the dirty limit. We show that the critical Josephson current may change sign, and the considered SINIS junction may become a π junction if the voltage drop across the ${N/S}_a$ interface exceeds a certain value $({\mathrm{eV}}_N>\Delta /\sqrt{2})$. The ac Josephson effect may arise even if the current flows only through the ${N/S}_a$ interface, whereas the current through the $S_b/N$ interface is absent.