Design of novel 1×4 power splitter by directional coupling between photonic crystal waveguides

In the design process of a novel photonic crystal 1×4 power splitter, the coupling of three parallel photonic crystal waveguides can be considered as a multimode interference system in the two-dimensional square photonic crystal, the positions of output waveguides are decided by the positions of periodic twofold image which are formed by the self-imaging effect of multimode interference. The identical output optical power in each output port of the device can be realized by inserting dielectric rod E and F in the junction between the multimode waveguides and lateral single-mode output waveguides. The transmission characteristics of the splitter are investigated by using the finite-difference time-domain method. The results show that the transmittance of this splitter can be as high as 95.4% for λ=1.55μm when the radius of the inserted dielectric rods of E and F is 0.34r.