Fabrication of MMI splitters by photosensitive hybrid sol-gel technology

The perfect photosensitive SiO2 films with no cracks, small roughness and smooth surface are fabricated by the organic/inorganic hybrid sol-gel method. Then, the main performance of multi-mode interference(MMI) power splitters with the two kinds of UV-light imprinting structures, buried rectangular waveguide and exposed rectangular waveguide, is discussed using three-dimensional finite difference beam propagation method (FD-BPM). The simulated results show that the MMI optical power splitter with the buried structure has superior length, width, depth tolerances and wider bandwidth compared with that with the exposed structure, which is fit for dense wavelength division multiplex(DWDM) system. Finally, 1 × 4 MMI power splitters with buried rectangular waveguide structure are fabricated by the UV-light imprinting and organic/inorganic hybrid sol-gel technology. The insertion loss is about 8.1-8.8 dB, and the splitting uniformity is lower than 1 dB at the wavelength of 1550 nm.