Cascaded Wide-Angle Optical Power Splitter

Cascaded wide-angle optical power splitters operating at 1.55μm and 0.6328μm are demonstrated. The splitter is essentially a symmetric Y-junction waveguide. To reduce the device length, the bending structure of the Y-junction is replaced by simplified coherently-coupled waveguide segments. Moreover, zinc and nickel co-diffused lithium niobate (Zn-Ni:LiNbO3) waveguide, free of lithium outdiffusion, is used to improve the confinement of optical field. The measured transmission efficiencies are more than 80% and the maximal imbalances are less than 0.5 dB at both wavelengths. The distances between the closer two output waveguides are 119 μm and 53 μm at 1.55 μm and 0.6328 μm, respectively, when the bending angles of the segments are designed as 0.5°, 1.5°, 2.5°, 3°, 2.5°, 1.5°, and 0.5° according to the simplified coherent coupling (SCC) theory. Moreover, simulation results show that the power transmission efficiency of an SCC splitter is 10% higher than that of an S-bend one.