Design and fabrication of a 1xN InGaAsP/InP MMI power splitter with a weakly guided ridge waveguide structure

1 x N InGaAsP/InP multimode interference (MMI) power splitters with relaxed fabrication tolerance were fabricated by using a weakly guided ridge structure. We applied the effective index method and the finite difference beam propagation method for device design a;nd simulation. The metalorganic vapor-phase epitaxy grown wafer was processed by conventional photolithography and CH4/H-2 reactive ion etching fbr device fabrication. The Propagation loss was found to be 2.91 dB/cm at 1.55 mu m for the fabricated 3-mu m- wide straight waveguides. For TE polarization, the excess losses measured at 1.5 mu were 0.91, 0.83, and 1.02 dB for 1 x 2, 1 x 4, and 1 x 8 MMI power splitters, respectively, and the splitting ratios were below 0.68 dB. Also, the polarization dependence of these devices was investigated. These results show that 1 x N power splitters with a weakly guided ridge structure have,advantages over a tightly guided ridge structure, i.e., ease in manufacture, which can be used to divide power equally between the N (2, 4 and:8) split output ports with low excess loss, low splitting ratio, low polarization dependence, and acceptable fabrication tolerance.