Abstract: The invention pertains to a polymeric phased array comprising an MMI input coupler with N inputs and an MMI output coupler with M outputs, N and M being natural numbers greater than or equal to 1, wherein the couplers are optically connected by means of an optical array comprising a series of optical waveguides, each of which differs from its nearest neighbour, in optical path length by a predetermined fixed amount, wherein the physical length of all the waveguides is substantially equal. The said phased arrays are less sensitive to changes in temperature and physical aging.